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@@ -33,3 +33,4 @@ saved_model/**/* filter=lfs diff=lfs merge=lfs -text
 *.zip filter=lfs diff=lfs merge=lfs -text
 *.zst filter=lfs diff=lfs merge=lfs -text
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+bin/telemetry filter=lfs diff=lfs merge=lfs -text

CHANGELOG.md

@@ -0,0 +1,1328 @@
+This is the Changelog for Judge0 CE. The Changelog for Judge0 Extra CE can be found [here](https://github.com/judge0/judge0/blob/extra/CHANGELOG.md). Learn more about their difference [here](https://github.com/judge0/judge0#flavors).
+
+# v1.13.1 (2024-04-18)
+Security researcher [Daniel Cooper](https://www.linkedin.com/in/daniel-cooper4) (@stacksparrow4) found three critical vulnerabilities in Judge0 versions `<= 1.13.0`, which this release fixes. Thank you, Daniel, for your contribution.
+
+## Security Fixes
+This release fixes the following security vulnerabilities:
+- [CVE-2024-28185](https://github.com/judge0/judge0/security/advisories/GHSA-h9g2-45c8-89cf)
+- [CVE-2024-28189](https://github.com/judge0/judge0/security/advisories/GHSA-3xpw-36v7-2cmg)
+- [CVE-2024-29021](https://github.com/judge0/judge0/security/advisories/GHSA-q7vg-26pg-v5hr)
+
+## Deployment Procedure
+Judge0 is collecting telemetry data to help improve the product and understand its use in various production environments. Read more about telemetry [here](https://github.com/judge0/judge0/blob/v1.13.1/TELEMETRY.md).
+
+#### System Requirements
+Please note that Judge0 has only been tested on **Linux** and might not work on other systems; thus, we do not provide support for it.
+
+We recommend using Ubuntu 22.04, on which you need to do the following update of GRUB:
+1. Use `sudo` to open file `/etc/default/grub`
+2. Add `systemd.unified_cgroup_hierarchy=0` in the value of `GRUB_CMDLINE_LINUX` variable.
+4. Apply the changes: `sudo update-grub`
+5. Restart your server: `sudo reboot`
+
+Additionally, make sure you have [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose) installed.
+
+#### Deployment Steps
+1. Download and extract the release archive:
+```
+wget https://github.com/judge0/judge0/releases/download/v1.13.1/judge0-v1.13.1.zip
+unzip judge0-v1.13.1.zip
+```
+
+2. Visit [this website](https://www.random.org/passwords/?num=1&len=32&format=plain&rnd=new) to generate a random password.
+3. Use the generated password to update the variable `REDIS_PASSWORD` in the `judge0.conf` file.
+4. Visit again [this website](https://www.random.org/passwords/?num=1&len=32&format=plain&rnd=new) to generate another random password.
+5. Use the generated password to update the variable `POSTGRES_PASSWORD` in the `judge0.conf` file.
+6. Run all services and wait a few seconds until everything is initialized:
+```
+cd judge0-v1.13.1
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+7. Your instance of Judge0 CE v1.13.1 is now up and running; visit docs at `http://<IP ADDRESS OF YOUR SERVER>:2358/docs`.
+
+
+# v1.13.0 (2021-03-10)
+Huge thanks to [**Filtered**](https://www.filtered.ai) for sponsoring this release.
+
+## New Features
+- Added support for `enable_network` configuration flag. With the new `ALLOW_ENABLE_NETWORK` configuration variable, usage of this flag can be permitted or denied. Furthermore, with the new `ENABLE_NETWORK` configuration variable the default value of this flag can be set for every submission.
+    - Commits: [@62a00520](https://github.com/judge0/judge0/commit/62a00520692c2b7a8bf0f54528aee8fbbf864f36)
+- Added `USE_DOCS_AS_HOMEPAGE` configuration variable, which allows you to show or hide Judge0 homepage. **Now, by default, Judge0 homepage is empty** and does not show the API documentation. However, you can still access the API documentation via `/docs`.
+    - Issues: [#257](https://github.com/judge0/judge0/issues/257)
+
+## Bug Fixes
+- Fixed the bug where the wrong number of workers would be reported via `/workers`.
+	- Issues: [#256](https://github.com/judge0/judge0/issues/256)
+
+## Security Fixes
+- **HIGH** Fixed a security bug where certain submission configuration settings would allow the user to run a program that would run infinetly long. With this fix `wall_time_limit` **must** be at least 1 second.
+	- Commits: [@fce8d97a](https://github.com/judge0/judge0/commit/fce8d97ae765e87c4584115fcb73bd288d64d815)
+
+## Other Changes
+- Allow setting the `max_file_size` and `stack_limit` to 0 kB.
+	- Issues: [#242](https://github.com/judge0/judge0/issues/242)
+	- Commits: [@bf7c1284](https://github.com/judge0/judge0/commit/bf7c1284fe756d348154546ad8a6280ce3af5eb2) [@5a4b79ab](https://github.com/judge0/judge0/commit/5a4b79abd19c20b7b26ef70cf862da25f5fd8008)
+- Allow setting the `cpu_time_limit` and `cpu_extra_time` to 0 seconds.
+	- Commits: [@fce8d97a](https://github.com/judge0/judge0/commit/fce8d97ae765e87c4584115fcb73bd288d64d815)
+- Updated to a port 2358 as a new **default port for Judge0** as a online code execution service.
+	- Issues: [#205](https://github.com/judge0/judge0/issues/205)
+	- Commits: [@ea9c7c97](https://github.com/judge0/judge0/commit/ea9c7c975e0697d66ada910ec7806d3c28ad4a03)
+- Updated the default number of Judge0 Workers, those that acutally run the user's code, to the 2*[`nproc`](https://linux.die.net/man/1/nproc). This has been shown as a good choice for general purpose use-case.
+	- Commits: [@113d9c74](https://github.com/judge0/judge0/commit/113d9c74b4659cf6707e748eb6e04701ce67d3f0)
+- Updated the default number of Rails threads to `nproc` and Rails processes to 2. This has been shown as a good choice for general purpose use-case.
+	- Commits: [@113d9c74](https://github.com/judge0/judge0/commit/113d9c74b4659cf6707e748eb6e04701ce67d3f0)
+- Updated Let's Encrypt Docker image for deployment with HTTPS.
+	- Commits: [@86b7f8e8](https://github.com/judge0/judge0/commit/86b7f8e8d0154ab5044db91c537872ea8deb7343)
+- Updated Nginx proxy Docker image that is used in development setup and deployment with HTTPS.
+	- Commits: [@83f5b175](https://github.com/judge0/judge0/commit/83f5b175d0925fe21374e9c70d7fbb4e6941fa9c)
+- Fixed documentation typos. Thank you @balababa.
+	- Pull Requests: [#245](https://github.com/judge0/judge0/pull/245)
+- Updated base image to `judge0/compilers:1.4.0` which uses updated Isolate to [@ad39cc4d](https://github.com/judge0/isolate/commit/ad39cc4d0fbb577fb545910095c9da5ef8fc9a1a).
+
+## Deployment Procedure
+Judge0 is collecting telemetry data to help understand how to improve the product and to better understand how Judge0 is used in various production environments. Read more about telemetry [here](https://github.com/judge0/judge0/blob/v1.13.0/TELEMETRY.md).
+
+Please note that Judge0 has only been tested on **Linux** and **macOS**, and might not work on Windows, thus we do not provide support for it.
+
+### With HTTP
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract the release archive:
+```
+wget https://github.com/judge0/judge0/releases/download/v1.13.0/judge0-v1.13.0.zip
+unzip judge0-v1.13.0.zip
+```
+
+3. Run all services and wait a few seconds until everything is initialized:
+```
+cd judge0-v1.13.0
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+4. Your instance of Judge0 CE v1.13.0 is now available at `http://<IP ADDRESS OF YOUR SERVER>:2358`.
+
+### With HTTPS (SSL/TLS)
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract the release archive:
+```
+wget https://github.com/judge0/judge0/releases/download/v1.13.0/judge0-v1.13.0-https.zip
+unzip judge0-v1.13.0-https.zip
+```
+
+3. Change directory to `judge0-v1.13.0-https`:
+```
+cd judge0-v1.13.0-https
+```
+4. Edit `docker-compose.yml` and change variables `VIRTUAL_HOST`, `LETSENCRYPT_HOST` and `LETSENCRYPT_EMAIL`.
+5. Run all services and wait a few seconds until everything is initialized:
+```
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+6. Your instance of Judge0 CE v1.13.0 is now available at `https://<YOUR DOMAIN>`.
+
+
+# v1.12.0 (2020-10-18)
+## New Features
+- Added support for invalidating statistics cache using the `invalidate_cache` query parameter.
+    - Commits: [@561c2a30](https://github.com/judge0/judge0/commit/561c2a309d98680801628fc2d79ea17e885e1d66)
+- Added rake task `judge0:run_in_queue` to manually run submissions that might have stuck in the `In Queue` state.
+    - Commits: [@c3b87d23](https://github.com/judge0/judge0/commit/c3b87d232a8e922b5ae04f5afdb12fc49b2ec003)
+- Added support for specifying `CALLBACKS_MAX_TRIES` and `CALLBACKS_TIMEOUT`. This is a global configuration that applies to all submissions that have defined webhooks (HTTP callbacks).
+    - Commits: [@c4bb76ec](https://github.com/judge0/judge0/commit/c4bb76ec866bce6b07bd733391291e720f40ef96)
+- Added support for submission caching to reduce the number of unnecessary database hits. Cache duration can be controlled with the `SUBMISSION_CACHE_DURATION` variable which is currently set to 1 second by default. Submissions are only cached for `GET /submissions/<token>` route. Cache files are written to the server's file system and are automatically cleared every day at midnight. This is the first step toward more serious submission caching in the future.
+    - Commits: [@7a33c61c](https://github.com/judge0/judge0/commit/7a33c61c8dcbcdbf31fd4d93ef76cc2f1f5e154b) [@0b344920](https://github.com/judge0/judge0/commit/0b344920bd70bd2bf4b2a53fc78b6b145c298cbc)
+
+## Improvements
+- Update PostgreSQL to 13.0 and Redis to 6.0.
+    - Commits: [@05330f11](https://github.com/judge0/judge0/commit/05330f112b26850a18c59a380991f8b401eae224) [@be300efa](https://github.com/judge0/judge0/commit/be300efa4bec7653303bb76681f91588550c25ef)
+- Reschedule failed jobs after 0.1 seconds with 100 attempts.
+    - Commits: [@f7265cf8](https://github.com/judge0/judge0/commit/f7265cf8d53ef5319a9e96e1bf7bee8649b09762) [@e003c888](https://github.com/judge0/judge0/commit/e003c888e64ea4f4a83e1acce8d355b666276aa2)
+- Send only submission ID to the worker and not the whole serialized submission.
+    - Commits: [@f7265cf8](https://github.com/judge0/judge0/commit/f7265cf8d53ef5319a9e96e1bf7bee8649b09762) [@4222c090](https://github.com/judge0/judge0/commit/4222c090689deb1a356cf6c2588b81b9904124f1)
+- Automatically restart Judge0 server without the need for Docker restart policies. Use the `RESTART_MAX_TRIES` variable to specify the maximum number of restart tries.
+    - Commits: [@65756516](https://github.com/judge0/judge0/commit/65756516b331265ec5a6742372ecc57ecbb8ca71) [@c0fd97e2](https://github.com/judge0/judge0/commit/c0fd97e2359172f7fc8bf7195089ab7c19845728)
+
+## Bug Fixes
+- Fixed a bug in the `is_project` method of submission model where an exception was raised and not handled properly due to unknown language.
+    - Commits: [@6426ac61](https://github.com/judge0/judge0/commit/6426ac61ea6723fcf6b93b72024ec39e3dc4b7f2)
+
+## Other Changes
+- Use Docker volumes for storing Postgres and Redis data instead of mounting directories. This is now the new recommended setting.
+    - Commits: [@600f5aaa](https://github.com/judge0/judge0/commit/600f5aaa3facfef38dd2cd5df25ac248734ace97)
+- Added Resque Web to the development stack.
+    - Commits: [@3762a635](https://github.com/judge0/judge0/commit/3762a6355b8911d8d8e13d91869edeef9bec0a4f)
+- Changed binding ports for Nginx and documentation server in the development stack. Nginx is now bound to port 80, and the development server to port 3001.
+    - Commits: [@3762a635](https://github.com/judge0/judge0/commit/3762a6355b8911d8d8e13d91869edeef9bec0a4f)
+- Removed port bindings of Postgres and Redis in the development stack.
+    - Commits: [@3762a635](https://github.com/judge0/judge0/commit/3762a6355b8911d8d8e13d91869edeef9bec0a4f)
+- Added PgBouncer to the development stack for testing and experimenting.
+    - Commits: [@24b3227a](https://github.com/judge0/judge0/commit/24b3227a0a47dcca89041e1c08106d08a413dcf3)
+- Changed recommended values for `POSTGRES_DB` and `POSTGRES_USER`. Both are now `judge0`.
+    - Commits: [@745f4455](https://github.com/judge0/judge0/commit/745f4455937d15f2f6093539e9ab96c40bc506da)
+
+## Deployment Procedure
+Judge0 is collecting telemetry data to help understand how to improve the product and to better understand how Judge0 is used in various production environments. Read more about telemetry [here](https://github.com/judge0/judge0/blob/v1.12.0/TELEMETRY.md).
+
+Please note that Judge0 has only been tested on **Linux** and **macOS**, and might not work on Windows, thus we do not provide support for it.
+
+### With HTTP
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/judge0/releases/download/v1.12.0/judge0-v1.12.0.zip
+unzip judge0-v1.12.0.zip
+```
+
+3. Run all services and wait a few seconds until everything is initialized:
+```
+cd judge0-v1.12.0
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+4. Your instance of Judge0 v1.12.0 is now available at `http://<IP ADDRESS OF YOUR SERVER>`.
+
+### With HTTPS (SSL/TLS)
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/judge0/releases/download/v1.12.0/judge0-v1.12.0-https.zip
+unzip judge0-v1.12.0-https.zip
+```
+
+3. Change directory to `judge0-v1.12.0-https`:
+```
+cd judge0-v1.12.0-https
+```
+4. Edit `docker-compose.yml` and change variables `VIRTUAL_HOST`, `LETSENCRYPT_HOST` and `LETSENCRYPT_EMAIL`.
+5. Run all services and wait a few seconds until everything is initialized:
+```
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+6. Your instance of Judge0 v1.12.0 is now available at `https://<YOUR DOMAIN>`.
+
+
+# v1.11.0 (2020-09-09)
+## New Features
+- Added queue size into response of `/workers`.
+    - Issues: [#210](https://github.com/judge0/judge0/issues/210)
+    - Commits: [@7ee1b10c](https://github.com/judge0/judge0/commit/7ee1b10c79576e745140f02d49446d57a208bcca)
+
+## Improvements
+- Set configuration defaults even if `judge0.conf` is not present. Thank you @vvalchev.
+    - Issues: [#206](https://github.com/judge0/judge0/issues/206)
+    - Commits: [@8c42f7be](https://github.com/judge0/judge0/commit/8c42f7befcdf8d70fa8cb4e3ba549c828c38164d)
+
+## Other Changes
+- Updated documentation with some better explanation on the use of `base64_encoded` query parameter. Thank you @mejibyte.
+
+## Deployment Procedure
+Judge0 is collecting telemetry data to help understand how to improve the product and to better understand how Judge0 is used in various production environments. Read more about telemetry [here](https://github.com/judge0/judge0/blob/v1.11.0/TELEMETRY.md).
+
+Please note that Judge0 has only been tested on **Linux** and might not work on Windows or macOS, thus we do not provide support for these systems.
+
+### With HTTP
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/judge0/releases/download/v1.11.0/judge0-v1.11.0.zip
+unzip judge0-v1.11.0.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-v1.11.0
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+4. Your instance of Judge0 v1.11.0 is now available at `http://<IP ADDRESS OF YOUR SERVER>`.
+
+### With HTTPS (SSL/TLS)
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/judge0/releases/download/v1.11.0/judge0-v1.11.0-https.zip
+unzip judge0-v1.11.0-https.zip
+```
+
+3. Change directory to `judge0-v1.11.0-https`:
+```
+cd judge0-v1.11.0-https
+```
+4. Edit `docker-compose.yml` and change variables `VIRTUAL_HOST`, `LETSENCRYPT_HOST` and `LETSENCRYPT_EMAIL`.
+5. Run all services and wait few seconds until everything is initialized:
+```
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+6. Your instance of Judge0 v1.11.0 is now available at `https://<YOUR DOMAIN>`.
+
+
+# v1.10.0 (2020-07-27)
+## New Features
+- Added support for multi-file programs in the terms of adding a new special language called **Multi-file program**. In total there are now **47 active languages**.
+
+|ID|Name|Note|
+|---|---|---|
+|89|Multi-file program||
+
+Multi-file programs allow you specify your own compilation and execution scripts that Judge0 will use.
+
+To use multi-file program feature you need to choose a language called *Multi-file program* whoose ID is **89**. Moreover, you need to send all program files with `additional_files` attribute. With multi-file programs attribute `source_code` cannot be used, i.e. all files should be sent with `additional_files` attribute.
+
+For the Judge0 to know how to compile and execute your multi-file program you need to provide two special files that should be available in the root of the `.zip` archive that you are sending with `additional_files` attribute. These files should be named `compile` and `run`, and are expected to be Bash scripts that know how to compile and execute your multi-file program. If your multi-file program does not need compilation step, then you don't need to provide `compile` script. Take a look at [this example](https://github.com/judge0/examples/tree/master/cpp-project-01) to learn how to use this feature to compile and run multi-file C++ project that uses CMake.
+
+## Other Changes
+- Updated gems.
+
+## Deployment Procedure
+Judge0 is collecting telemetry data to help understand how to improve the product and to better understand how Judge0 is used in various production environments. Read more about telemetry [here](https://github.com/judge0/api/blob/v1.10.0/TELEMETRY.md).
+
+### With HTTPS (SSL/TLS)
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.10.0/judge0-v1.10.0-https.zip
+unzip judge0-v1.10.0-https.zip
+```
+
+3. Change directory to `judge0-v1.10.0-https`:
+```
+cd judge0-v1.10.0-https
+```
+4. Edit `docker-compose.yml` and change variables `VIRTUAL_HOST`, `LETSENCRYPT_HOST` and `LETSENCRYPT_EMAIL`.
+5. Run all services and wait few seconds until everything is initialized:
+```
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+6. Your instance of Judge0 v1.10.0 is now available at `https://<YOUR DOMAIN>`.
+
+### With HTTP
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.10.0/judge0-v1.10.0.zip
+unzip judge0-v1.10.0.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-v1.10.0
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+4. Your instance of Judge0 v1.10.0 is now available at `http://<IP ADDRESS OF YOUR SERVER>`.
+
+
+# v1.9.0 (2020-06-10)
+Huge thanks to [**Filtered**](https://www.filtered.ai) for sponsoring this release.
+
+## New Features
+- Added support for configuration variable `RAILS_SERVER_PROCESSES` which allows to create multiple processes for handling requests.
+
+## Other Changes
+- Updated gems.
+
+## Deployment Procedure
+Judge0 is collecting telemetry data to help understand how to improve the product and to better understand how Judge0 is used in various production environments. Read more about telemetry [here](https://github.com/judge0/api/blob/v1.9.0/TELEMETRY.md).
+
+### With HTTPS (SSL/TLS)
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.9.0/judge0-v1.9.0-https.zip
+unzip judge0-v1.9.0-https.zip
+```
+
+3. Change directory to `judge0-v1.9.0-https`:
+```
+cd judge0-v1.9.0-https
+```
+4. Edit `docker-compose.yml` and change variables `VIRTUAL_HOST`, `LETSENCRYPT_HOST` and `LETSENCRYPT_EMAIL`.
+5. Run all services and wait few seconds until everything is initialized:
+```
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+6. Your instance of Judge0 v1.9.0 is now available at `https://<YOUR DOMAIN>`.
+
+### With HTTP
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.9.0/judge0-v1.9.0.zip
+unzip judge0-v1.9.0.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-v1.9.0
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+4. Your instance of Judge0 v1.9.0 is now available at `http://<IP ADDRESS OF YOUR SERVER>`.
+
+
+# v1.8.0 (2020-05-28)
+Huge thanks to [**Filtered**](https://www.filtered.ai) for sponsoring this release.
+
+## New Features
+- Added **4 new languages**, and in total there are now **46 active languages**.
+
+|ID|Name|Note|
+|---|---|---|
+|85|Perl (5.28.1)|Sponsored by [Filtered](https://www.filtered.ai).|
+|86|Clojure (1.10.1)|Sponsored by [Filtered](https://www.filtered.ai).|
+|87|F# (.NET Core SDK 3.1.202)|Sponsored by [Filtered](https://www.filtered.ai).|
+|88|Groovy (3.0.3)|Sponsored by [Filtered](https://www.filtered.ai).|
+
+## Bug Fixes
+- Fixed `/statistics` route caching.
+    - Issues: [#184](https://github.com/judge0/api/issues/184)
+    - Commits: [@83c5cfc6](https://github.com/judge0/api/commit/83c5cfc6b4ae95fa8bdef0bba2eee98829207dd0)
+
+## Other Changes
+- Updated gems.
+    - Commits: [@0c766273](https://github.com/judge0/api/commit/0c766273d7cb8009695a3aa1903719c8474a233d) [@700e6582](https://github.com/judge0/api/commit/700e65829910ee860ddfa43254847f564c0d5623)
+- Increased default `CPU_TIME_LIMIT` to 5, `CPU_EXTRA_TIME` to 1, `MAX_CPU_EXTRA_TIME` to 5 and `WALL_TIME_LIMIT` to 10 seconds.
+    - Commits: [@77961ab9](https://github.com/judge0/api/commit/77961ab9f6b1015d5bdb5150e29d8de06478f38c)
+- Changed `HOME` environment variable value for sandbox to `/tmp`.
+    - Commits: [@77961ab9](https://github.com/judge0/api/commit/77961ab9f6b1015d5bdb5150e29d8de06478f38c)
+- Updated *isolate* to [@9be3ff6f](https://github.com/judge0/isolate/commit/9be3ff6ff0670763e564912a6662730e55b69536).
+
+## Deployment Procedure
+Judge0 API is collecting telemetry data to help understand how to improve the product and to better understand how the Judge0 API is used in various production environments. Read more about telemetry [here](https://github.com/judge0/api/blob/v1.8.0/TELEMETRY.md).
+
+### With HTTPS (SSL/TLS)
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.8.0/judge0-api-v1.8.0-https.zip
+unzip judge0-api-v1.8.0-https.zip
+```
+
+3. Change directory to `judge0-api-v1.8.0-https`:
+```
+cd judge0-api-v1.8.0-https
+```
+4. Edit `docker-compose.yml` and change variables `VIRTUAL_HOST`, `LETSENCRYPT_HOST` and `LETSENCRYPT_EMAIL`.
+5. Run all services and wait few seconds until everything is initialized:
+```
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+6. Your instance of Judge0 API v1.8.0 is now available at `https://<YOUR DOMAIN>`.
+
+### With HTTP
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.8.0/judge0-api-v1.8.0.zip
+unzip judge0-api-v1.8.0.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.8.0
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+4. Your instance of Judge0 API v1.8.0 is now available at `http://<IP ADDRESS OF YOUR SERVER>`.
+
+
+# v1.7.1 (2020-05-06)
+## Bug Fixes
+- Compile Swift before executing since default file size limit of 1MB for execution is not enough for Swift to run successfully. Compilation has a file size limit of 4MB by default which seems to be enough for Swift to compile. Thanks @OliverwengFiltered.
+    - Issues: [#154](https://github.com/judge0/api/issues/154)
+    - Commits: [@371e2463](https://github.com/judge0/api/commit/371e246312a41242033d916f1f4fea3db80015b7)
+- Fixed environment loading for Telemetry Client.
+    - Commits: [@bd16119c](https://github.com/judge0/api/commit/bd16119ccde52798b5d354afdd5e008df6d5b940)
+
+## Other Changes
+- Set `VIRTUAL_HOST` environment variable in Dockerfile to value `3000`.
+- Updated Telemetry Client to version `c62fa63d`.
+- Added separated Docker Compose files for server and workers.
+- Renamed service `worker` to `workers` and `api` to `server`.
+
+## Deployment Procedure
+Judge0 API is collecting telemetry data to help understand how to improve the product and to better understand how the Judge0 API is used in various production environments. Read more about telemetry [here](https://github.com/judge0/api/blob/v1.7.1/TELEMETRY.md).
+
+### With HTTPS (SSL/TLS)
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.7.1/judge0-api-v1.7.1-https.zip
+unzip judge0-api-v1.7.1-https.zip
+```
+
+3. Change directory to `judge0-api-v1.7.1-https`:
+```
+cd judge0-api-v1.7.1-https
+```
+4. Edit `docker-compose.yml` and change variables `VIRTUAL_HOST`, `LETSENCRYPT_HOST` and `LETSENCRYPT_EMAIL`.
+5. Run all services and wait few seconds until everything is initialized:
+```
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+6. Your instance of Judge0 API v1.7.1 is now available at `https://<YOUR DOMAIN>`.
+
+### With HTTP
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.7.1/judge0-api-v1.7.1.zip
+unzip judge0-api-v1.7.1.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.7.1
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+4. Your instance of Judge0 API v1.7.1 is now available at `http://<IP ADDRESS OF YOUR SERVER>`.
+
+
+# v1.7.0 (2020-05-05)
+Huge thanks to sponsors of this release: [**Filtered**](https://www.filtered.ai) and [**Evalart**](https://evalart.com).
+
+## New Features
+- Added **10 new languages**, and in total there are now **42 active languages**.
+
+|ID|Name|Note|
+|---|---|---|
+|75|C (Clang 7.0.1)||
+|76|C++ (Clang 7.0.1)||
+|77|COBOL (GnuCOBOL 2.2)|Sponsored by [Evalart](https://evalart.com).|
+|78|Kotlin (1.3.70)|Sponsored by [Filtered](https://www.filtered.ai).|
+|79|Objective-C (Clang 7.0.1)|Sponsored by [Filtered](https://www.filtered.ai) and [Evalart](https://evalart.com).|
+|80|R (4.0.0)|Sponsored by [Filtered](https://www.filtered.ai).|
+|81|Scala (2.13.2)|Sponsored by [Filtered](https://www.filtered.ai).|
+|82|SQL (SQLite 3.27.2)|Sponsored by [Filtered](https://www.filtered.ai). (*)|
+|83|Swift (5.2.3)|Sponsored by [Filtered](https://www.filtered.ai) and [Evalart](https://evalart.com).|
+|84|Visual Basic.Net (vbnc 0.0.0.5943)|Sponsored by [Filtered](https://www.filtered.ai).|
+
+(*) Watch [this asciicast](https://asciinema.org/a/326975) to learn how to use this language.
+
+## Other Changes
+- Increased default `MAX_MEMORY_LIMIT` to 512000.
+    - Commits: [@3dcbfc96](https://github.com/judge0/api/commit/3dcbfc9605a0f81680afd890a239ef2b60739186)
+- Set compile CPU time limit to `MAX_CPU_TIME_LIMIT`.
+    - Commits: [@3dcbfc96](https://github.com/judge0/api/commit/3dcbfc9605a0f81680afd890a239ef2b60739186)
+- Set compile wall time limit to `MAX_WALL_TIME_LIMIT`.
+    - Commits: [@3dcbfc96](https://github.com/judge0/api/commit/3dcbfc9605a0f81680afd890a239ef2b60739186)
+- Redirect input from `/dev/null` when compiling. Thank you @gollux for your [help](https://github.com/ioi/isolate/issues/90).
+    - Commits: [@42b89a7c](https://github.com/judge0/api/commit/42b89a7cdb333253460023fa7bcbf1640329d48b)
+
+## Deployment Procedure
+### With HTTPS (SSL/TLS)
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.7.0/judge0-api-v1.7.0-https.zip
+unzip judge0-api-v1.7.0-https.zip
+```
+
+3. Change directory to `judge0-api-v1.7.0-https`:
+```
+cd judge0-api-v1.7.0-https
+```
+4. Edit `docker-compose.yml` and change variables `VIRTUAL_HOST`, `LETSENCRYPT_HOST` and `LETSENCRYPT_EMAIL`.
+5. Run all services and wait few seconds until everything is initialized:
+```
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+6. Your instance of Judge0 API v1.7.0 is now available at `https://<YOUR DOMAIN>`.
+
+### With HTTP
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.7.0/judge0-api-v1.7.0.zip
+unzip judge0-api-v1.7.0.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.7.0
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+4. Your instance of Judge0 API v1.7.0 is now available at `http://<IP ADDRESS OF YOUR SERVER>`.
+
+
+# v1.6.0 (2020-05-01)
+## New Features
+- Added support for automatically redirecting stderr to stdout of the running program with the configuration flag `redirect_stderr_to_stdout`. Added configuration variable `REDIRECT_STDERR_TO_STDOUT` that can be used for setting default behaviour for every submission.
+    - Commits: [@8e6617aa](https://github.com/judge0/api/commit/8e6617aae2d4dd9106ab610738dcc5e59633b2f4)
+- Added configuration variable `DISALLOW_ORIGIN` that can be used for disabling CORS only for specific origins.
+    - Commits: [@f61b5496](https://github.com/judge0/api/commit/f61b54965f12a9ccb0d19d3449bc818b12881127) [@a927c9db](https://github.com/judge0/api/commit/a927c9db0f47aa8bd3d2b7dd1774a829a0cbc6f7)
+- Added configuration variables `ALLOW_IP` and `DISALLOW_IP` that can be used for allowing/disallowing only specific IP addresses that can use instance of Judge0 API.
+    - Commits: [@4fd0f34b](https://github.com/judge0/api/commit/4fd0f34b8f08fe808dd6b19ca96bac1e15b2a6f3)
+- Added support for built in maintenance mode that can be enabled with configuration variables `MAINTENANCE_MODE` and `MAINTENANCE_MESSAGE`. In maintenance mode clients cannot create or delete submissions i.e. they cannot create new database changes.
+    - Commits: [@201221e2](https://github.com/judge0/api/commit/201221e22bbe64e960306b2dcf22cc6941892e3f)
+- Added support for universal field `*` which returns all attributes of a submission.
+    - Commits: [@521cc2e2](https://github.com/judge0/api/commit/521cc2e2e94f1b469c084680020953e76af6e2b9)
+- Added route `GET /statistics` which returns some basic and useful information about Judge0 API instance. Statistic report is cached for 10 minutes.
+    - Commits: [@a24db632](https://github.com/judge0/api/commit/a24db6326b793e093a64dea877c26402c585c680) [@621c50f1](https://github.com/judge0/api/commit/621c50f1f8056e716ff073a404556e51ab3a34c3) [@eead8067](https://github.com/judge0/api/commit/eead806786fac79e13cee9fca0fe7196f116680b)
+- Added basic support for callbacks which are called with HTTP verb `PUT`.
+    - Pull Requests: [#98](https://github.com/judge0/api/pull/98)
+    - Issues: [#33](https://github.com/judge0/api/issues/33)
+    - Commits: [@41e846b1](https://github.com/judge0/api/commit/41e846b156bc7c071b9d2827271d87cfaee584f7)
+- Added support for presetting custom additional files in a sandbox.
+    - Issues: [#32](https://github.com/judge0/api/issues/32) [#88](https://github.com/judge0/api/issues/88)
+    - Commits: [@7829db87](https://github.com/judge0/api/commit/7829db878895acdb3adfa063df03204c87cd1589) [@6d1f4293](https://github.com/judge0/api/commit/6d1f4293000a479a0cae0e9c4dc905652297199b) [@6573c52f](https://github.com/judge0/api/commit/6573c52faccee55e467457ab54742dd189a48a4b)
+- Added routes `GET /submissions/batch` and `POST /submissions/batch` batch create and show or
+submissions.
+    - Issues: [#34](https://github.com/judge0/api/issues/34)
+    - Commits: [@6420156b](https://github.com/judge0/api/commit/6420156b0ad6526bed3d638be3e824c996cd33cd) [@87859b58](https://github.com/judge0/api/commit/87859b58e4c348249237f2a7881c1c26dcb5d785) [@595c7e11](https://github.com/judge0/api/commit/595c7e11d6ede28d6bef7b98c2675f29e1ae2a9a) [@04c900c9](https://github.com/judge0/api/commit/04c900c9d9c325720ed5c807b46272a500c22a97) [@cb676d6c](https://github.com/judge0/api/commit/cb676d6c7fe3a6e9144a9246329c6223e48c6511)
+
+## Improvements
+- Use Redis queue with name that corresponds with the current Judge0 API version. This allows multiple instances of different versions of Judge0 API to use the same Redis instance.
+    - Commits: [@dd6b62d7](https://github.com/judge0/api/commit/dd6b62d73c6ab0ef028711258e2edb141c1ba81a)
+- Refactored submission field checking.
+    - Commits: [@9acefdbc](https://github.com/judge0/api/commit/9acefdbc7959ff88770ea186d12a085158bce521)
+- Refactored setting up of default values.
+    - Commits: [@a14ae5d5](https://github.com/judge0/api/commit/a14ae5d540db75a0ade3a4dbfc12e6120d0c1ee2)
+
+## Bug Fixes
+- Fixed a bug that ignored custom setting of configuration variables `enable_per_process_and_thread_time_limit` and `enable_per_process_and_thread_memory_limit`.
+    - Commits: [@a6f693a0](https://github.com/judge0/api/commit/a6f693a0ced221a28a3f4b4815e9d3baf8c2c4c0)
+- Fixed a bug where cgroups flags for isolate were chosen in the wrong conditions.
+    - Commits: [@4116b9cb](https://github.com/judge0/api/commit/4116b9cb988816cad81f6b5c3265da01a8cec120)
+- Fixed a bug that caused `Internal Error` because sandbox cleanup failed.
+    - Pull Requests: [#126](https://github.com/judge0/api/pull/126)
+    - Issues: [#123](https://github.com/judge0/api/issues/123) [#143](https://github.com/judge0/api/issues/143)
+    - Commits: [@514aec53](https://github.com/judge0/api/commit/514aec53dca8f1fb9f8f153add05c14d263d6624)
+- Fixed a bug where low `memory_limit` would cause `Internal Error`. Minimum required value for `memory_limit` is now 2048.
+    - Commits: [@655ccf27](https://github.com/judge0/api/commit/655ccf277aad2c11371ca223c5386380c0bfc4ba)
+
+## Security Fixes
+- Fixed a bug that allowed creation of an arbitrary size of the compile output.
+    - Commits: [@5fc7b823](https://github.com/judge0/api/commit/5fc7b823a7bccecb148c57615da0be9d52f1585a)
+
+## Other Changes
+- Do not implicitly force wide open CORS settings when in development mode. I.e. variable `ALLOW_ORIGIN` can now also be used in development mode.
+    - Commits: [@a3a24c5c](https://github.com/judge0/api/commit/a3a24c5c6fab31ab845905b7120146b18bfe7dbb)
+- Removed output of configuration settings when server or worker starts.
+    - Commits: [@7061de7a](https://github.com/judge0/api/commit/7061de7a69ffb07b335e44f7120619558a6cf79d)
+- Updated all the gems except Rails to the latest versions.
+    - Commits: [@230c7a77](https://github.com/judge0/api/commit/230c7a777edf96d6d8848618c15c239134d1f29b) [@69a9fe11](https://github.com/judge0/api/commit/69a9fe1193fb437e103a56b9691196e3687e5e7e) [@095588e6](https://github.com/judge0/api/commit/095588e6642211a123e5091227271de27fc700d5)
+- Changed default value of `enable_per_process_and_thread_memory_limit` to `false`.
+    - Commits: [@4116b9cb](https://github.com/judge0/api/commit/4116b9cb988816cad81f6b5c3265da01a8cec120)
+- Don't show total number of workers in `/workers` that is determined with configuration variable `COUNT` because that number is not relevant.
+    - Commits: [@99939b89](https://github.com/judge0/api/commit/99939b89a58d21fc7c6a43fcec90550f75681e39)
+- Changed the default port to `80` in Docker Compose file.
+    - Commits: [@6ab67d6b](https://github.com/judge0/api/commit/6ab67d6b1e723ce1e959dd17c899605c340bc6ed)
+- Limited the log size to 100 MB in Docker Compose file.
+    - Commits: [@435c7d79](https://github.com/judge0/api/commit/435c7d792babfda8564dd432d31d4edc5a694ab9)
+- Added logging to `run-workers` script.
+    - Commits: [@381265a2](https://github.com/judge0/api/commit/381265a295c130c54d540641ba071a18447d8223)
+- Updated dummy client default values.
+- Added Docker Compose file for HTTPS support.
+- Refactored all development and production scripts from `scripts` directory.
+- Refactored `judge0-api.conf` file.
+
+## Deployment Procedure
+### With HTTPS (SSL/TLS)
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.6.0/judge0-api-v1.6.0-https.zip
+unzip judge0-api-v1.6.0-https.zip
+```
+
+3. Change directory to `judge0-api-v1.6.0-https`:
+```
+cd judge0-api-v1.6.0-https
+```
+4. Edit `docker-compose.yml` and change variables `VIRTUAL_HOST`, `LETSENCRYPT_HOST` and `LETSENCRYPT_EMAIL`.
+5. Run all services and wait few seconds until everything is initialized:
+```
+docker-compose up -d db redis nginx letsencrypt
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+6. Your instance of Judge0 API v1.6.0 is now available at `https://<YOUR DOMAIN>`.
+
+### With HTTP
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.6.0/judge0-api-v1.6.0.zip
+unzip judge0-api-v1.6.0.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.6.0
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+4. Your instance of Judge0 API v1.6.0 is now available at `http://<IP ADDRESS OF YOUR SERVER>`.
+
+
+# v1.5.0 (2020-01-01)
+## New Features
+- Added **30 new languages**, archived 42 languages and kept active 2 languages from the last release. In total, there are now **32 active languages** that can be used and all are updated to their latest versions as of the date of this release.  Archived languages cannot be used anymore. Following table shows a status of every language that API supports.
+    - Issues: [#51](https://github.com/judge0/api/issues/51) [#90](https://github.com/judge0/api/issues/90) [#106](https://github.com/judge0/api/issues/106) [#131](https://github.com/judge0/api/issues/131)
+    - Commits: [@f86a546c](https://github.com/judge0/api/commit/f86a546cb9c90eeaedf08862d2a2a2a76293a87f)
+
+|ID|Name|Status|
+|---|---|---|
+|1|Bash (4.4)|archived|
+|2|Bash (4.0)|archived|
+|3|Basic (fbc 1.05.0)|archived|
+|4|C (gcc 7.2.0)|archived|
+|5|C (gcc 6.4.0)|archived|
+|6|C (gcc 6.3.0)|archived|
+|7|C (gcc 5.4.0)|archived|
+|8|C (gcc 4.9.4)|archived|
+|9|C (gcc 4.8.5)|archived|
+|10|C++ (g++ 7.2.0)|archived|
+|11|C++ (g++ 6.4.0)|archived|
+|12|C++ (g++ 6.3.0)|archived|
+|13|C++ (g++ 5.4.0)|archived|
+|14|C++ (g++ 4.9.4)|archived|
+|15|C++ (g++ 4.8.5)|archived|
+|16|C# (mono 5.4.0.167)|archived|
+|17|C# (mono 5.2.0.224)|archived|
+|18|Clojure (1.8.0)|archived|
+|19|Crystal (0.23.1)|archived|
+|20|Elixir (1.5.1)|archived|
+|21|Erlang (OTP 20.0)|archived|
+|22|Go (1.9)|archived|
+|23|Haskell (ghc 8.2.1)|archived|
+|24|Haskell (ghc 8.0.2)|archived|
+|25|Insect (5.0.0)|archived|
+|26|Java (OpenJDK 9 with Eclipse OpenJ9)|archived|
+|27|Java (OpenJDK 8)|archived|
+|28|Java (OpenJDK 7)|archived|
+|29|JavaScript (nodejs 8.5.0)|archived|
+|30|JavaScript (nodejs 7.10.1)|archived|
+|31|OCaml (4.05.0)|archived|
+|32|Octave (4.2.0)|archived|
+|33|Pascal (fpc 3.0.0)|archived|
+|34|Python (3.6.0)|archived|
+|35|Python (3.5.3)|archived|
+|36|Python (2.7.9)|archived|
+|37|Python (2.6.9)|archived|
+|38|Ruby (2.4.0)|archived|
+|39|Ruby (2.3.3)|archived|
+|40|Ruby (2.2.6)|archived|
+|41|Ruby (2.1.9)|archived|
+|42|Rust (1.20.0)|archived|
+|43|Plain Text|Renamed from `Text (plain text)`.|
+|44|Executable|Not changed.|
+|45|Assembly (NASM 2.14.02)|**NEW**|
+|46|Bash (5.0.0)|**NEW**|
+|47|Basic (FBC 1.07.1)|**NEW**|
+|48|C (GCC 7.4.0)|**NEW**|
+|49|C (GCC 8.3.0)|**NEW**|
+|50|C (GCC 9.2.0)|**NEW**|
+|51|C# (Mono 6.6.0.161)|**NEW**|
+|52|C++ (GCC 7.4.0)|**NEW**|
+|53|C++ (GCC 8.3.0)|**NEW**|
+|54|C++ (GCC 9.2.0)|**NEW**|
+|55|Common Lisp (SBCL 2.0.0)|**NEW**|
+|56|D (DMD 2.089.1)|**NEW**|
+|57|Elixir (1.9.4)|**NEW**|
+|58|Erlang (OTP 22.2)|**NEW**|
+|59|Fortran (GFortran 9.2.0)|**NEW**|
+|60|Go (1.13.5)|**NEW**|
+|61|Haskell (GHC 8.8.1)|**NEW**|
+|62|Java (OpenJDK 13.0.1)|**NEW**|
+|63|JavaScript (Node.js 12.14.0)|**NEW**|
+|64|Lua (5.3.5)|**NEW**|
+|65|OCaml (4.09.0)|**NEW**|
+|66|Octave (5.1.0)|**NEW**|
+|67|Pascal (FPC 3.0.4)|**NEW**|
+|68|PHP (7.4.1)|**NEW**|
+|69|Prolog (GNU Prolog 1.4.5)|**NEW**|
+|70|Python (2.7.17)|**NEW**|
+|71|Python (3.8.1)|**NEW**|
+|72|Ruby (2.7.0)|**NEW**|
+|73|Rust (1.40.0)|**NEW**|
+|74|TypeScript (3.7.4)|**NEW**|
+
+- Added route `GET /languages/:id` for getting all attributes of specified language.
+    - Commits: [@2a31e963](https://github.com/judge0/api/commit/2a31e96326651b90b59403d811ae48445fa4202e)
+- Added route `GET /languages/all` for getting a list of all languages (archived and active).
+    - Commits: [@2a31e963](https://github.com/judge0/api/commit/2a31e96326651b90b59403d811ae48445fa4202e)
+- Added route `DELETE /submissions/:token` for deleting specified submission. Only authorized requests (users) are allowed to delete a submission.
+    - Commits: [@3365e3c8](https://github.com/judge0/api/commit/3365e3c8da28bd273dbd7a21417e75fe393d83ee)
+- Added configuration variable `ENABLE_SUBMISSION_DELETE` with default value set to `false`. By default you cannot delete a submission as long as this variable is set to `false`. When set to `true` then only authorized requests (users) can delete specific submission.
+    - Commits: [@79e1de95](https://github.com/judge0/api/commit/79e1de95a4a6d2e022af557b96056b009a90be5e)
+- Added info routes `GET /about`, `GET /version`, `GET /license` and `GET /isolate`. Last route `GET /isolate` returns result from [`isolate --version`](https://github.com/ioi/isolate) command.
+    - Commits: [@9f5202a5](https://github.com/judge0/api/commit/9f5202a501f8cc2375be68908c6fbd0249ac3dd1)
+
+## Improvements
+- Updated base image to `judge0/api-base:1.0.0` which uses [Debian "buster"](https://www.debian.org/releases/buster/) and has installed Ruby 2.7.0.
+    - Issues: [#113](https://github.com/judge0/api/issues/113)
+    - Commits: [@f86a546c](https://github.com/judge0/api/commit/f86a546cb9c90eeaedf08862d2a2a2a76293a87f)
+- Improved handling of an server error when one or more submission attributes cannot be serialized to JSON without Base64 encoding. User now gets an error with instructions to use `base64_encoded=true` query parameter.
+    - Issues: [#107](https://github.com/judge0/api/issues/107) [#129](https://github.com/judge0/api/issues/129) [#130](https://github.com/judge0/api/issues/130)
+    - Commits: [@cdcaa512](https://github.com/judge0/api/commit/cdcaa5122f96c90c0a9fcd16273a808c0ff06d4e)
+
+## Bug Fixes
+- Fixed example in configuration for using `ALLOW_ORIGIN` variable with multiple origins.
+    - Commits: [@21d0202a](https://github.com/judge0/api/commit/21d0202ae16aa2e92853d146ba8fedb0c6bb6ab2)
+- Fixed a bug where value of `MAX_MAX_PROCESSES_AND_OR_THREADS` was used as default value for `max_processes_and_or_threads` attribute of submission, whereas `MAX_PROCESSES_AND_OR_THREADS` should be used.
+    - Commits: [@563f8ea2](https://github.com/judge0/api/commit/563f8ea264dad9396b4e7743cef187c785cbee67)
+
+## Other Changes
+- Increased maximum allowed `compiler_options` and `command_line_arguments` length to 512 characters.
+    - Issues: [#122](https://github.com/judge0/api/issues/122)
+    - Commits: [@3d4df3bf](https://github.com/judge0/api/commit/3d4df3bfe661ddff9ee7e6c015fa4403baf8be85)
+- Increased default value of `MAX_PROCESSES_AND_OR_THREADS` to 60.
+    - Commits: [@563f8ea2](https://github.com/judge0/api/commit/563f8ea264dad9396b4e7743cef187c785cbee67)
+- Increased default value of `MAX_MAX_PROCESSES_AND_OR_THREADS` to 120.
+    - Commits: [@563f8ea2](https://github.com/judge0/api/commit/563f8ea264dad9396b4e7743cef187c785cbee67)
+- Changed default value of `RAILS_ENV` to `production`.
+    - Commits: [@be55ca65](https://github.com/judge0/api/commit/be55ca656b524c5e99e75bd6d6207c4a078f5689)
+- Changed default value of `INTERVAL` to 0.1.
+    - Commits: [@be55ca65](https://github.com/judge0/api/commit/be55ca656b524c5e99e75bd6d6207c4a078f5689)
+- Updated year in LICENSE.
+    - Commits: [@679fb2ba](https://github.com/judge0/api/commit/679fb2bad981a22dcaebdd63baff506678b36939)
+- Added environment variables `JUDGE0_{HOMEPAGE,SOURCE_CODE,MAINTAINER,VERSION}`. Isolate sandbox inherits these variables and they are now available for use in user code.
+    - Commits: [@9f5202a5](https://github.com/judge0/api/commit/9f5202a501f8cc2375be68908c6fbd0249ac3dd1)
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.5.0/judge0-api-v1.5.0.zip
+unzip judge0-api-v1.5.0.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.5.0
+docker-compose up -d db redis
+sleep 10s
+docker-compose up -d
+sleep 5s
+```
+
+4. Your instance of Judge0 API v1.5.0 is now available at `http://<IP OF YOUR SERVER>:3000`.
+
+
+# v1.4.0 (2019-10-31)
+## New Features
+- Added support for `compiler_options` and `command_line_arguments`.
+- Added configuration variables `ENABLE_COMPILER_OPTIONS`, `ALLOWED_LANGUAGES_FOR_COMPILER_OPTIONS` and `ENABLE_COMMAND_LINE_ARGUMENTS` for controlling usage of compiler options and command line arguments.
+
+## Security Improvements
+- Run compilation process for compiled languages inside sandbox and use values of *limit configuration variables* for controlling sandbox resources.
+- Move application location from `/usr/src/api` to `/api` to prevent untrusted code from reading it.
+    - Commits: [@0f1b07fe](https://github.com/judge0/api/commit/0f1b07fe0f75141ec82431ef28ad939d73e418a3)
+
+## Other Changes
+- Don't link math library for C language by default. You now need to send `-lm` in `compiler_options`.
+    - Commits: [@619a3bbe](https://github.com/judge0/api/commit/619a3bbed204b22c71e012f0de0faabf6f846d70)
+
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.4.0/judge0-api-v1.4.0.zip
+unzip judge0-api-v1.4.0.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.4.0
+docker-compose up -d
+sleep 10s
+```
+
+4. Your instance of Judge0 API v1.4.0 is now available at `http://<IP OF YOUR SERVER>:3000`.
+
+
+# v1.3.1 (2019-09-16)
+## Improvements
+- Improved handling exec format error by introducing new status **Exec Format Error**.
+    - Commits: [@93a60115](https://github.com/judge0/api/commit/93a601159187d67d1ca52e8c06ebecd8318ed6c3)
+
+## Bug Fixes
+- Fixed bug where execution of Go code with no `main` package would induce `execve("./main"): No such file or directory` because Go compiler wouldn't create `main` binary.
+    - Commits: [@93a60115](https://github.com/judge0/api/commit/93a601159187d67d1ca52e8c06ebecd8318ed6c3)
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.3.1/judge0-api-v1.3.1.zip
+unzip judge0-api-v1.3.1.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.3.1
+docker-compose up -d
+sleep 10s
+```
+
+4. Your instance of Judge0 API v1.3.1 is now available at `http://<IP OF YOUR SERVER>:3000`.
+
+
+# v1.3.0 (2019-09-15)
+## New Features
+- Added `MAX_QUEUE_SIZE` variable that defines a maximum submission queue size. If there is a new submission request and the queue is full, then that submission will be rejected.
+    - Commits: [@a2bcdecb](https://github.com/judge0/api/commit/a2bcdecbb99dbd8d3875e2f95bdf71f12e34f495)
+
+## Improvements
+- Improved worker shutdown procedure. Workers are now gracefully shutdown on `docker stop`.
+    - Commits: [@2ae0cd31](https://github.com/judge0/api/commit/2ae0cd31153dca4218638096d390ee6f84896236)
+
+## Bug Fixes
+- Fixed a bug where authentication token was auto converted to integer.
+    - Issues: [#101](https://github.com/judge0/api/issues/101)
+    - Commits: [@b92c4970](https://github.com/judge0/api/commit/b92c49705c687e955f91dc6638015f14bbcad97c)
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.3.0/judge0-api-v1.3.0.zip
+unzip judge0-api-v1.3.0.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.3.0
+docker-compose up -d
+sleep 10s
+```
+
+4. Your instance of Judge0 API v1.3.0 is now available at `http://<IP OF YOUR SERVER>:3000`.
+
+
+# v1.2.2 (2019-09-07)
+## Securty Fixes
+- Fixed a bug that allowed anybody to read `judge0-api.conf` file. This bug was introduced in version [v1.2.1](https://github.com/judge0/api/releases/tag/v1.2.1) when config was mounted into container. With this fix, config is still mounted into container but not in `/usr/src/api` folder but rather in `/`. Root folder is not binded in isolate sandbox, whereas `/usr/src/api` is.
+  - Commits: [@121c8f9d](https://github.com/judge0/api/commit/121c8f9de8d89b45c5fec69266d625b375e3181e)
+
+## Other Changes
+- Don't allow execution of scripts in `/usr/src/api` folder.
+  - Commits: [@121c8f9d](https://github.com/judge0/api/commit/121c8f9de8d89b45c5fec69266d625b375e3181e)
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.2.2/judge0-api-v1.2.2.zip
+unzip judge0-api-v1.2.2.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.2.2
+docker-compose up -d
+sleep 10s
+```
+
+4. Your instance of Judge0 API v1.2.2 is now available at `http://<IP OF YOUR SERVER>:3000`.
+
+
+# v1.2.1 (2019-08-24)
+## Improvements
+- Improved config loading. Config can now be changed and reload just with `docker-compose restart` command.
+  - Commits: [@06fc37f1](https://github.com/judge0/api/commit/06fc37f16571840e87c41658807da20a08358926)
+
+## Bug Fixes
+- Fixed bug in `run-worker` script that didn't consider `COUNT` config variable.
+  - Issues: [#91](https://github.com/judge0/api/issues/91)
+  - Commits: [@06fc37f1](https://github.com/judge0/api/commit/06fc37f16571840e87c41658807da20a08358926)
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.2.1/judge0-api-v1.2.1.zip
+unzip judge0-api-v1.2.1.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.2.1
+docker-compose up -d
+sleep 10s
+```
+
+4. Your instance of Judge0 API v1.2.1 is now available at `http://<IP OF YOUR SERVER>:3000`.
+
+
+# v1.2.0-nim0.20.0 (2019-06-26)
+This image contains only [The Nim Programming Language](https://nim-lang.org). Free public instance of this image is available on https://nim.api.judge0.com.
+
+This image was build for the purpose of creating dedicated web playground for this language, and in the future I will add and deploy every new release of it. In the [`nim`](https://github.com/judge0/api-base/tree/nim) branch of Judge0 API Base I will follow and install new releases of Nim, and in the [`nim`](https://github.com/judge0/api/tree/nim) branch of Judge0 API I will maintain a Judge0 API that only has Nim available.
+
+Free playground for the Nim programming language that uses Judge0 API is available at https://nim.ide.judge0.com.
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.2.0-nim0.20.0/judge0-api-v1.2.0-nim0.20.0.zip
+unzip judge0-api-v1.2.0-nim0.20.0.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.2.0-nim0.20.0
+docker-compose up -d
+sleep 10s
+```
+
+4. Your instance of Judge0 API v1.2.0-nim0.20.0 is now available at `http://<IP OF YOUR SERVER>:3000`.
+
+
+# v1.2.0-vlang0.1.3 (2019-06-26)
+This image contains only [The V Programming Language](https://vlang.io), specifically only V compiler built from commit [@b00a47be](https://github.com/vlang/v/commit/b00a47be66e868b087146feb7999fd72f2af3da0). Free public instance of this image is available on https://vlang.api.judge0.com.
+
+This image was build for the purpose of creating dedicated web playground for this new programming language, and in the future I will add and deploy every new release of it. In the [`vlang`](https://github.com/judge0/api-base/tree/vlang) branch of Judge0 API Base I will follow and install new releases of V, and in the [`vlang`](https://github.com/judge0/api/tree/vlang) branch of Judge0 API I will maintain a Judge0 API that only has V available.
+
+Free playground for the V programming language that uses Judge0 API is available at https://vlang.ide.judge0.com.
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.2.0-vlang0.1.3/judge0-api-v1.2.0-vlang0.1.3.zip
+unzip judge0-api-v1.2.0-vlang0.1.3.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.2.0-vlang0.1.3
+docker-compose up -d
+sleep 10s
+```
+
+4. Your instance of Judge0 API v1.2.0-vlang0.1.3 is now available at `http://<IP OF YOUR SERVER>:3000`.
+
+
+# v1.2.0 (2019-06-17)
+## New Features
+- Added new language **Executable** that allows executing custom executable files.
+  - Commits: [@0ab08351](https://github.com/judge0/api/commit/0ab08351f59ae75d9626b6941be3728b48e835db)
+- Added new configuration variables: `REDIS_PASSWORD`, `REDIS_PORT` and `POSTGRES_PORT`.
+  - Commits: [@962d7d1d](https://github.com/judge0/api/commit/962d7d1dcff051357de492f2d31e996405b1d125)
+
+## Improvements
+- Improved `run-server` and `run-worker` scripts.
+  - Commits: [@e1b3564b](https://github.com/judge0/api/commit/e1b3564b5f262c610c42a45879e313eca93e720f)
+
+## Bug Fixes
+- Fixed `/etc/apt/sources.list` that prevented package update.
+  - Issues: [#84](https://github.com/judge0/api/issues/84)
+  - Commits: [@7fdca3cf](https://github.com/judge0/api/commit/7fdca3cfa5f3bddefbe2ae1e12a18ba18a7e5f63)
+- Fixed cleanup bug that didn't remove sandbox files if `tmp` directory was not empty.
+  - Commits: [@50ee4dbf](https://github.com/judge0/api/commit/50ee4dbf841bc9d0ce195380aaa1c5ee957ee2b7)
+- Fixed another UTF-8 problem with Python that @nguyenvanquan7826 reported.
+  - Issues: [#69](https://github.com/judge0/api/issues/69)
+  - Commits: [@64635c98](https://github.com/judge0/api/commit/64635c98f7c0475e33b9b4629a6da8bc20fff60a)
+
+## Other Changes
+- Updated some gems that had security issues.
+  - Pull Requests: [#77](https://github.com/judge0/api/pull/77) [#78](https://github.com/judge0/api/pull/78) [#79](https://github.com/judge0/api/pull/79) [#80](https://github.com/judge0/api/pull/80) [#81](https://github.com/judge0/api/pull/81) [#82](https://github.com/judge0/api/pull/82)
+  - Commits: [@e1b3564b](https://github.com/judge0/api/commit/e1b3564b5f262c610c42a45879e313eca93e720f)
+- Prepared Isolate Job for accepting custom compile flags.
+  - Commits: [@4f2dde1f](https://github.com/judge0/api/commit/4f2dde1f79e32545da219de5cea7c5aaf25869cb)
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.2.0/judge0-api-v1.2.0.zip
+unzip judge0-api-v1.2.0.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.2.0
+docker-compose up -d
+sleep 10s
+```
+
+4. Your instance of Judge0 API v1.2.0 is now available at `http://<IP OF YOUR SERVER>:3000`.
+
+
+# v1.1.5-python3.6.8 (2019-03-08)
+On @guvenim [request](https://github.com/judge0/api/issues/67) I have built an Judge0 API image that contains just Python 3.6.8. This release also shows what changes are necessary in [api-base](https://github.com/judge0/api-base/commit/bfde9426e4a3d44098dab2a2d082e02de2bc5be5) and [api](https://github.com/judge0/api/commit/9f9f5cd0577a724d66be934c11d2e57b2b3fc705) when you only want to use languages that you need.
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.1.5-python3.6.8/judge0-api-v1.1.5-python3.6.8.zip
+unzip judge0-api-v1.1.5-python3.6.8.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.1.5-python3.6.8
+docker-compose up -d
+sleep 10s
+```
+
+4. Your instance of Judge0 API v1.1.5-python3.6.8 is now available at `http://<IP OF YOUR SERVER>:3000`.
+
+
+# v1.1.5 (2019-02-17)
+## Bug Fixes
+- Fixed problem with assigning compile output to submission when rerunning submission.
+  - Commits: [@c3cd0232](https://github.com/judge0/api/commit/c3cd023258a4ec48949d4ee2310bc39a2f40cac9)
+
+## Other Changes
+- Remove unwanted newlines from compile output.
+  - Commits: [@c3cd0232](https://github.com/judge0/api/commit/c3cd023258a4ec48949d4ee2310bc39a2f40cac9)
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.1.5/judge0-api-v1.1.5.zip
+unzip judge0-api-v1.1.5.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.1.5
+docker-compose up -d
+sleep 10s
+```
+
+4. Your instance of Judge0 API v1.1.5 is now available at `http://<IP OF YOUR SERVER>:3000`.
+
+
+# v1.1.4 (2019-02-17)
+## Bug Fixes
+- Fixed problem with assigning compile output to submission when compile output is not empty.
+  - Commits: [@22403707](https://github.com/judge0/api/commit/224037078325dfe02f5fbf191a55513582ca84b5)
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.1.4/judge0-api-v1.1.4.zip
+unzip judge0-api-v1.1.4.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.1.4
+docker-compose up -d
+sleep 10s
+```
+
+4. Your instance of Judge0 API v1.1.4 is now available at `http://<IP OF YOUR SERVER>:3000`.
+
+
+# v1.1.3 (2019-02-15)
+## Improvements
+- Improved cleanup of sandbox by deleting stdin, stdout, stderr and meta file before running isolate cleanup.
+  - Commits: [@1dcfaf98](https://github.com/judge0/api/commit/1dcfaf98536fc55fe200c57de10540de64936654)
+
+## Bug Fixes
+- Fixed problem with compile output that contained invalid byte sequence in UTF-8.
+  - Commits: [@37d46b14](https://github.com/judge0/api/commit/37d46b140c75aaafeca35ffc36e53746e0905387)
+- Fixed problem with submissions not changing their post-run attributes after rerun if compile error occured.
+  - Commits: [@37d46b14](https://github.com/judge0/api/commit/37d46b140c75aaafeca35ffc36e53746e0905387)
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.1.3/judge0-api-v1.1.3.zip
+unzip judge0-api-v1.1.3.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.1.3
+docker-compose up -d
+sleep 10s
+```
+
+4. Your instance of Judge0 API v1.1.3 is now available at `http://<IP OF YOUR SERVER>:3000`.
+
+
+# v1.1.2 (2019-02-15)
+## Improvements
+- Improved reading from stdin and writing to stdout, stderr and meta. They are now not available in sandbox.
+  - Commits: [@1f135c1a](https://github.com/judge0/api/commit/1f135c1a53f5039b52de5e9c78764c80a7ed3945) [@350ff3a4](https://github.com/judge0/api/commit/350ff3a4705b6d83ef4f1188de52586cbb87e693)
+
+## Bug Fixes
+- Fixed writing of source code and stdin to disc, they are now written as binary files to avoid UTF-8 problems.
+  - Commits: [@519efbea](https://github.com/judge0/api/commit/519efbea1548f9dab5a95032af2cfa88fc319c65)
+- Fixed problem with stripping output that contained invalid byte sequence in UTF-8.
+  - Commits: [@4c994c67](https://github.com/judge0/api/commit/4c994c67630d6679a636a656ba0041ba6a680219)
+
+## Other Changes
+- Use `judge0/api-base:0.3.0` as base image which uses [isolate@18554e83](https://github.com/ioi/isolate/commit/18554e83793508acd1032d0cf4229a332c43085e).
+  - Commits: [@350ff3a4](https://github.com/judge0/api/commit/350ff3a4705b6d83ef4f1188de52586cbb87e693)
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.1.2/judge0-api-v1.1.2.zip
+unzip judge0-api-v1.1.2.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.1.2
+docker-compose up -d
+sleep 10s
+```
+
+4. Your instance of Judge0 API v1.1.2 is now available at `http://<IP OF YOUR SERVER>:3000`.
+
+
+# v1.1.1 (2019-02-13)
+## Bug Fixes
+- Fixed a problem when `strip` method was called on a `nil` class when expected output was `nil`.
+  - Commits: [@b25153e9](https://github.com/judge0/api/commit/b25153e9450569c995e8f3afe036fed4ad58726c)
+
+## Other Changes
+- Don't let worker update submission's `finished_at` attribute if it already exists. This allows Judge0 API administrators to manually rerun submissions from command line and preserve initial timestamps if some unexpected error occured.
+  - Commits: [@b25153e9](https://github.com/judge0/api/commit/b25153e9450569c995e8f3afe036fed4ad58726c)
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.1.1/judge0-api-v1.1.1.zip
+unzip judge0-api-v1.1.1.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.1.1
+docker-compose up -d
+sleep 10s
+```
+
+4. Your instance of Judge0 API v1.1.1 is now available at `http://<IP OF YOUR SERVER>:3000`.
+
+
+# v1.1.0 (2019-02-10)
+## New Features
+- Added `-lm` compile flag to link with math library when compiling C source code.
+  - Pull Requests: [#60](https://github.com/judge0/api/pull/60)
+- Added fixed time limit of 10 seconds for compilation.
+  - Issues: [#63](https://github.com/judge0/api/issues/63) [#64](https://github.com/judge0/api/issues/64)
+  - Commits: [@2f05ce2c](https://github.com/judge0/api/commit/2f05ce2c9305fccaeb0c08e23d645736593d787e)
+
+## Improvements
+- Improved procedure of seeding database with languages. Seeding is now idempotent.
+  - Commits: [@72cff961](https://github.com/judge0/api/commit/72cff9616db20bed128a38111e3c28dbfc75696e)
+
+## Bux Fixes
+- Fixed versions of Postgres and Redis in Docker Compose files.
+  - Issues: [#20](https://github.com/judge0/api/issues/20) [#38](https://github.com/judge0/api/issues/38) [#40](https://github.com/judge0/api/issues/40) [#45](https://github.com/judge0/api/issues/45) [#47](https://github.com/judge0/api/issues/47) [#56](https://github.com/judge0/api/issues/56) [#57](https://github.com/judge0/api/issues/57)
+  - Commits: [@80a61629](https://github.com/judge0/api/commit/80a61629129af75e1d8a4bb167b349ab34cabfd3) [@90ec40cf](https://github.com/judge0/api/commit/90ec40cf5b4dc2ca6aa4c3af59326d431530cf80)
+- Fixed problem with workers stopping when they lost connection with Postgres or Redis.
+  - Commits: [@eee340b6](https://github.com/judge0/api/commit/eee340b650aeacc7971ce5e73652a7bfa9e243af)
+- Fixed problem of storing submission's stdout and stderr that contained invalid byte sequence in UTF-8.
+  - Commits: [@ff63c1bc](https://github.com/judge0/api/commit/ff63c1bc498a62101d4c074f5aa7b7a971550164)
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.1.0/judge0-api-v1.1.0.zip
+unzip judge0-api-v1.1.0.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.1.0
+docker-compose up -d
+sleep 10s
+```
+
+
+# v1.0.0 (2017-10-01)
+This is the first production ready release of Judge0 API.
+
+## Deployment Procedure
+1. Install [Docker](https://docs.docker.com) and [Docker Compose](https://docs.docker.com/compose).
+2. Download and extract release archive:
+```
+wget https://github.com/judge0/api/releases/download/v1.0.0/judge0-api-v1.0.0.zip
+unzip judge0-api-v1.0.0.zip
+```
+
+3. Run all services and wait few seconds until everything is initialized:
+```
+cd judge0-api-v1.0.0
+docker-compose up -d
+sleep 10s
+```
+
+4. Your instance of Judge0 API v1.0.0 is now available at `http://<IP OF YOUR SERVER>:3000`.

CODE_OF_CONDUCT.md

@@ -0,0 +1,76 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as
+contributors and maintainers pledge to making participation in our project and
+our community a harassment-free experience for everyone, regardless of age, body
+size, disability, ethnicity, sex characteristics, gender identity and expression,
+level of experience, education, socio-economic status, nationality, personal
+appearance, race, religion, or sexual identity and orientation.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment
+include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or
+ advances
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic
+ address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+ professional setting
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable
+behavior and are expected to take appropriate and fair corrective action in
+response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or
+reject comments, commits, code, wiki edits, issues, and other contributions
+that are not aligned to this Code of Conduct, or to ban temporarily or
+permanently any contributor for other behaviors that they deem inappropriate,
+threatening, offensive, or harmful.
+
+## Scope
+
+This Code of Conduct applies both within project spaces and in public spaces
+when an individual is representing the project or its community. Examples of
+representing a project or community include using an official project e-mail
+address, posting via an official social media account, or acting as an appointed
+representative at an online or offline event. Representation of a project may be
+further defined and clarified by project maintainers.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported by contacting the project team at [email protected]. All
+complaints will be reviewed and investigated and will result in a response that
+is deemed necessary and appropriate to the circumstances. The project team is
+obligated to maintain confidentiality with regard to the reporter of an incident.
+Further details of specific enforcement policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good
+faith may face temporary or permanent repercussions as determined by other
+members of the project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4,
+available at https://www.contributor-covenant.org/version/1/4/code-of-conduct.html
+
+[homepage]: https://www.contributor-covenant.org
+
+For answers to common questions about this code of conduct, see
+https://www.contributor-covenant.org/faq

Dockerfile

@@ -0,0 +1,52 @@
+FROM judge0/compilers:1.4.0 AS production
+
+ENV JUDGE0_HOMEPAGE "https://judge0.com"
+LABEL homepage=$JUDGE0_HOMEPAGE
+
+ENV JUDGE0_SOURCE_CODE "https://github.com/judge0/judge0"
+LABEL source_code=$JUDGE0_SOURCE_CODE
+
+ENV JUDGE0_MAINTAINER "Herman Zvonimir Došilović <[email protected]>"
+LABEL maintainer=$JUDGE0_MAINTAINER
+
+ENV PATH "/usr/local/ruby-2.7.0/bin:/opt/.gem/bin:$PATH"
+ENV GEM_HOME "/opt/.gem/"
+
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+      cron \
+      libpq-dev \
+      sudo && \
+    rm -rf /var/lib/apt/lists/* && \
+    echo "gem: --no-document" > /root/.gemrc && \
+    gem install bundler:2.1.4 && \
+    npm install -g --unsafe-perm [email protected]
+
+EXPOSE 2358
+
+WORKDIR /api
+
+COPY Gemfile* ./
+RUN RAILS_ENV=production bundle
+
+COPY cron /etc/cron.d
+RUN cat /etc/cron.d/* | crontab -
+
+COPY . .
+
+ENTRYPOINT ["/api/docker-entrypoint.sh"]
+CMD ["/api/scripts/server"]
+
+RUN useradd -u 1000 -m -r judge0 && \
+    echo "judge0 ALL=(ALL) NOPASSWD: ALL" > /etc/sudoers && \
+    chown judge0: /api/tmp/
+
+USER judge0
+
+ENV JUDGE0_VERSION "1.13.1"
+LABEL version=$JUDGE0_VERSION
+
+
+FROM production AS development
+
+CMD ["sleep", "infinity"]

Gemfile

@@ -0,0 +1,21 @@
+source 'https://rubygems.org'
+
+gem 'rails', '~> 6.1'
+gem 'pg', '~> 1.2'
+
+gem 'active_model_serializers', '~> 0.10'
+gem 'enumerations', '~> 2.3'
+gem 'httparty', '~> 0.21'
+gem 'pry-byebug', '~> 3.9'
+gem 'pry-rails', '~> 0.3'
+gem 'puma', '~> 5.6'
+gem 'rack-cors', '~> 1.1'
+gem 'redis', '< 4.6'
+gem 'resque', '~> 2.6'
+gem 'resque-scheduler', '~> 4.10'
+gem 'will_paginate', '~> 3.2'
+
+group :development do
+  gem 'annotate', '~> 3.0'
+  gem 'listen', '~> 3.2'
+end

Gemfile.lock

@@ -0,0 +1,244 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    actioncable (6.1.7.7)
+      actionpack (= 6.1.7.7)
+      activesupport (= 6.1.7.7)
+      nio4r (~> 2.0)
+      websocket-driver (>= 0.6.1)
+    actionmailbox (6.1.7.7)
+      actionpack (= 6.1.7.7)
+      activejob (= 6.1.7.7)
+      activerecord (= 6.1.7.7)
+      activestorage (= 6.1.7.7)
+      activesupport (= 6.1.7.7)
+      mail (>= 2.7.1)
+    actionmailer (6.1.7.7)
+      actionpack (= 6.1.7.7)
+      actionview (= 6.1.7.7)
+      activejob (= 6.1.7.7)
+      activesupport (= 6.1.7.7)
+      mail (~> 2.5, >= 2.5.4)
+      rails-dom-testing (~> 2.0)
+    actionpack (6.1.7.7)
+      actionview (= 6.1.7.7)
+      activesupport (= 6.1.7.7)
+      rack (~> 2.0, >= 2.0.9)
+      rack-test (>= 0.6.3)
+      rails-dom-testing (~> 2.0)
+      rails-html-sanitizer (~> 1.0, >= 1.2.0)
+    actiontext (6.1.7.7)
+      actionpack (= 6.1.7.7)
+      activerecord (= 6.1.7.7)
+      activestorage (= 6.1.7.7)
+      activesupport (= 6.1.7.7)
+      nokogiri (>= 1.8.5)
+    actionview (6.1.7.7)
+      activesupport (= 6.1.7.7)
+      builder (~> 3.1)
+      erubi (~> 1.4)
+      rails-dom-testing (~> 2.0)
+      rails-html-sanitizer (~> 1.1, >= 1.2.0)
+    active_model_serializers (0.10.13)
+      actionpack (>= 4.1, < 7.1)
+      activemodel (>= 4.1, < 7.1)
+      case_transform (>= 0.2)
+      jsonapi-renderer (>= 0.1.1.beta1, < 0.3)
+    activejob (6.1.7.7)
+      activesupport (= 6.1.7.7)
+      globalid (>= 0.3.6)
+    activemodel (6.1.7.7)
+      activesupport (= 6.1.7.7)
+    activerecord (6.1.7.7)
+      activemodel (= 6.1.7.7)
+      activesupport (= 6.1.7.7)
+    activestorage (6.1.7.7)
+      actionpack (= 6.1.7.7)
+      activejob (= 6.1.7.7)
+      activerecord (= 6.1.7.7)
+      activesupport (= 6.1.7.7)
+      marcel (~> 1.0)
+      mini_mime (>= 1.1.0)
+    activesupport (6.1.7.7)
+      concurrent-ruby (~> 1.0, >= 1.0.2)
+      i18n (>= 1.6, < 2)
+      minitest (>= 5.1)
+      tzinfo (~> 2.0)
+      zeitwerk (~> 2.3)
+    annotate (3.2.0)
+      activerecord (>= 3.2, < 8.0)
+      rake (>= 10.4, < 14.0)
+    builder (3.2.4)
+    byebug (11.1.3)
+    case_transform (0.2)
+      activesupport
+    coderay (1.1.3)
+    concurrent-ruby (1.2.3)
+    crass (1.0.6)
+    date (3.3.4)
+    enumerations (2.5.3)
+      activerecord
+      activesupport
+      i18n
+    erubi (1.12.0)
+    et-orbi (1.2.7)
+      tzinfo
+    ffi (1.15.5)
+    fugit (1.9.0)
+      et-orbi (~> 1, >= 1.2.7)
+      raabro (~> 1.4)
+    globalid (1.2.1)
+      activesupport (>= 6.1)
+    httparty (0.21.0)
+      mini_mime (>= 1.0.0)
+      multi_xml (>= 0.5.2)
+    i18n (1.14.1)
+      concurrent-ruby (~> 1.0)
+    jsonapi-renderer (0.2.2)
+    listen (3.7.1)
+      rb-fsevent (~> 0.10, >= 0.10.3)
+      rb-inotify (~> 0.9, >= 0.9.10)
+    loofah (2.22.0)
+      crass (~> 1.0.2)
+      nokogiri (>= 1.12.0)
+    mail (2.8.1)
+      mini_mime (>= 0.1.1)
+      net-imap
+      net-pop
+      net-smtp
+    marcel (1.0.2)
+    method_source (1.0.0)
+    mini_mime (1.1.5)
+    mini_portile2 (2.8.5)
+    minitest (5.22.2)
+    mono_logger (1.1.2)
+    multi_json (1.15.0)
+    multi_xml (0.6.0)
+    mustermann (3.0.0)
+      ruby2_keywords (~> 0.0.1)
+    net-imap (0.3.7)
+      date
+      net-protocol
+    net-pop (0.1.2)
+      net-protocol
+    net-protocol (0.2.2)
+      timeout
+    net-smtp (0.4.0.1)
+      net-protocol
+    nio4r (2.7.0)
+    nokogiri (1.14.5)
+      mini_portile2 (~> 2.8.2)
+      racc (~> 1.4)
+    pg (1.3.5)
+    pry (0.13.1)
+      coderay (~> 1.1)
+      method_source (~> 1.0)
+    pry-byebug (3.9.0)
+      byebug (~> 11.0)
+      pry (~> 0.13.0)
+    pry-rails (0.3.9)
+      pry (>= 0.10.4)
+    puma (5.6.8)
+      nio4r (~> 2.0)
+    raabro (1.4.0)
+    racc (1.7.3)
+    rack (2.2.8.1)
+    rack-cors (1.1.1)
+      rack (>= 2.0.0)
+    rack-protection (3.1.0)
+      rack (~> 2.2, >= 2.2.4)
+    rack-test (2.1.0)
+      rack (>= 1.3)
+    rails (6.1.7.7)
+      actioncable (= 6.1.7.7)
+      actionmailbox (= 6.1.7.7)
+      actionmailer (= 6.1.7.7)
+      actionpack (= 6.1.7.7)
+      actiontext (= 6.1.7.7)
+      actionview (= 6.1.7.7)
+      activejob (= 6.1.7.7)
+      activemodel (= 6.1.7.7)
+      activerecord (= 6.1.7.7)
+      activestorage (= 6.1.7.7)
+      activesupport (= 6.1.7.7)
+      bundler (>= 1.15.0)
+      railties (= 6.1.7.7)
+      sprockets-rails (>= 2.0.0)
+    rails-dom-testing (2.2.0)
+      activesupport (>= 5.0.0)
+      minitest
+      nokogiri (>= 1.6)
+    rails-html-sanitizer (1.6.0)
+      loofah (~> 2.21)
+      nokogiri (~> 1.14)
+    railties (6.1.7.7)
+      actionpack (= 6.1.7.7)
+      activesupport (= 6.1.7.7)
+      method_source
+      rake (>= 12.2)
+      thor (~> 1.0)
+    rake (13.1.0)
+    rb-fsevent (0.11.1)
+    rb-inotify (0.10.1)
+      ffi (~> 1.0)
+    redis (4.5.1)
+    redis-namespace (1.11.0)
+      redis (>= 4)
+    resque (2.6.0)
+      mono_logger (~> 1.0)
+      multi_json (~> 1.0)
+      redis-namespace (~> 1.6)
+      sinatra (>= 0.9.2)
+    resque-scheduler (4.10.2)
+      mono_logger (~> 1.0)
+      redis (>= 3.3)
+      resque (>= 1.27)
+      rufus-scheduler (~> 3.2, != 3.3)
+    ruby2_keywords (0.0.5)
+    rufus-scheduler (3.9.1)
+      fugit (~> 1.1, >= 1.1.6)
+    sinatra (3.1.0)
+      mustermann (~> 3.0)
+      rack (~> 2.2, >= 2.2.4)
+      rack-protection (= 3.1.0)
+      tilt (~> 2.0)
+    sprockets (4.2.1)
+      concurrent-ruby (~> 1.0)
+      rack (>= 2.2.4, < 4)
+    sprockets-rails (3.4.2)
+      actionpack (>= 5.2)
+      activesupport (>= 5.2)
+      sprockets (>= 3.0.0)
+    thor (1.3.1)
+    tilt (2.3.0)
+    timeout (0.4.1)
+    tzinfo (2.0.6)
+      concurrent-ruby (~> 1.0)
+    websocket-driver (0.7.6)
+      websocket-extensions (>= 0.1.0)
+    websocket-extensions (0.1.5)
+    will_paginate (3.3.1)
+    zeitwerk (2.6.13)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  active_model_serializers (~> 0.10)
+  annotate (~> 3.0)
+  enumerations (~> 2.3)
+  httparty (~> 0.21)
+  listen (~> 3.2)
+  pg (~> 1.2)
+  pry-byebug (~> 3.9)
+  pry-rails (~> 0.3)
+  puma (~> 5.6)
+  rack-cors (~> 1.1)
+  rails (~> 6.1)
+  redis (< 4.6)
+  resque (~> 2.6)
+  resque-scheduler (~> 4.10)
+  will_paginate (~> 3.2)
+
+BUNDLED WITH
+   2.1.4

LICENSE

@@ -0,0 +1,674 @@
+GNU GENERAL PUBLIC LICENSE
+   Version 3, 29 June 2007
+
+Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
+Everyone is permitted to copy and distribute verbatim copies
+of this license document, but changing it is not allowed.
+
+        Preamble
+
+The GNU General Public License is a free, copyleft license for
+software and other kinds of works.
+
+The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+the GNU General Public License is intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.  We, the Free Software Foundation, use the
+GNU General Public License for most of our software; it applies also to
+any other work released this way by its authors.  You can apply it to
+your programs, too.
+
+When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+them if you wish), that you receive source code or can get it if you
+want it, that you can change the software or use pieces of it in new
+free programs, and that you know you can do these things.
+
+To protect your rights, we need to prevent others from denying you
+these rights or asking you to surrender the rights.  Therefore, you have
+certain responsibilities if you distribute copies of the software, or if
+you modify it: responsibilities to respect the freedom of others.
+
+For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must pass on to the recipients the same
+freedoms that you received.  You must make sure that they, too, receive
+or can get the source code.  And you must show them these terms so they
+know their rights.
+
+Developers that use the GNU GPL protect your rights with two steps:
+(1) assert copyright on the software, and (2) offer you this License
+giving you legal permission to copy, distribute and/or modify it.
+
+For the developers' and authors' protection, the GPL clearly explains
+that there is no warranty for this free software.  For both users' and
+authors' sake, the GPL requires that modified versions be marked as
+changed, so that their problems will not be attributed erroneously to
+authors of previous versions.
+
+Some devices are designed to deny users access to install or run
+modified versions of the software inside them, although the manufacturer
+can do so.  This is fundamentally incompatible with the aim of
+protecting users' freedom to change the software.  The systematic
+pattern of such abuse occurs in the area of products for individuals to
+use, which is precisely where it is most unacceptable.  Therefore, we
+have designed this version of the GPL to prohibit the practice for those
+products.  If such problems arise substantially in other domains, we
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+How to Apply These Terms to Your New Programs
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+If you develop a new program, and you want it to be of the greatest
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+
+Judge0 is a robust and scalable open-source online code execution system.
+Copyright (C) 2016-2020  Herman Zvonimir Došilović
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
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+
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+Also add information on how to contact you by electronic and paper mail.
+
+If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
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+Judge0 Copyright (C) 2016-2020  Herman Zvonimir Došilović
+This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+This is free software, and you are welcome to redistribute it
+under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
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+For more information on this, and how to apply and follow the GNU GPL, see
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+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<http://www.gnu.org/philosophy/why-not-lgpl.html>.

PRIVACY_POLICY.md

@@ -0,0 +1,9 @@
+# Privacy Policy
+This document is for those who consume Judge0 and not for those who deploy Judge0 to their own infrastructure.
+
+If you deploy Judge0 to your own infrastructure then you should read about [telemetry](TELEMETRY.md).
+
+## Collected Data
+Judge0 does **not** store any personal information.
+
+For every submission Judge0 stores the data that has been well documented [here](https://api.judge0.com/#submissions-submission).

Rakefile

@@ -0,0 +1,7 @@
+require_relative 'config/application'
+require 'resque/tasks'
+require 'resque/scheduler/tasks'
+
+task 'resque:setup' => :environment
+
+Rails.application.load_tasks

SECURITY.md

@@ -0,0 +1,16 @@
+# Security Policy
+
+## Supported Versions
+
+| Version          | Supported          |
+| ---------------- | ------------------ |
+| >= 1.13.0        | :white_check_mark: |
+| >= 1.13.0-extra  | :white_check_mark: |
+| < 1.13.0         | :x:                |
+| < 1.13.0-extra   | :x:                |
+
+## Reporting a Vulnerability
+
+Please report vulnerability via GitHub or email at [email protected].
+
+Your reports will be reviewed ASAP, and an update will also be released ASAP.

SPONSORSHIP.md

@@ -0,0 +1,85 @@
+# Sponsorship
+Thank you for considering supporting this project and thus [me](https://github.com/hermanzdosilovic) and my work. There are many ways you can support this project and you might have different motivation or reason to do so. Whatever your reason or motivation is, thank you!
+
+Every donation is valuable and helps me keep this project free and open-source for everybody.
+
+## Common Support
+You can support this project by becoming a [Patron](https://www.patreon.com/hermanzdosilovic) or by donating via [PayPal](https://www.patreon.com/hermanzdosilovic) or [Revolut](https://pay.revolut.com/profile/hermancy5).
+
+This is the simplest yet very welcome and significant way for you to express your appreciation and support the project with your monthly or one-time donation.
+
+Thank you!
+
+## Development Sponsorship
+You can directly sponsor the development of the features, bug fixes or anything that is important to you, your organization or company. For the sake of simplicity in the following text I will just reffer to "features", but remember that it can be anything that you want to see in the project.
+
+Sponsored features are put on the top of the [priority list](https://github.com/judge0/judge0/projects) for one of the next releases and push the development forward by reducing the release cycles.
+
+### Sponsorship Protocol
+The protocol for development sponsorship is described below. Described protocol is based on two assumptions:
+1. You trust me. I will do the work in the agreed deadline.
+2. I trust you. You will donate agreed amount after the work is done.
+
+Moreover, with the following protocol I want to keep everything transparent as possible and in the spirit of the open-source values.
+
+#### 1. Issue Creation
+Create a new or choose an existing issue on the [Issues](https://github.com/judge0/judge0/issues) page. It can be anything from feature request, bug fix or documentation update. It can be anything that you would like to see in one of the next releases as soon as possible.
+
+#### 2. Declare Sponsorship
+Add a comment that you, your organization or company is willing to sponsor the development of this feature:
+
+```
+This feature will be sponsored by [me|ORGANIZATION NAME](URL).
+```
+
+It is important to note who is sponsoring the feature because the name of the sponsor (with the given URL) will be written in the release notes.
+
+If you, however, want to stay anonymous then comment:
+```
+This feature will be anonymously sponsored.
+```
+
+Even though the feature is anonymously sponsored it will be noted as such in the release notes.
+
+#### 3. (Optional) Specify Your Deadline
+If you have a deadline you want me to meet, please specify it. It can be anything from 1 day to 1 year.
+
+#### 4. Review and Validation
+I will then review the feature request and iteratate further with you on its specification before we agree on what exactly will be developed.
+
+This step is important because I want to develop exactly what you are asking for, so we need to be on the same page.
+
+I have a full right to reject and close the issue at any point if it does not match my vision of the direction in which the project should go.
+
+#### 5. Deadline and Offer
+I will then tell you in what release this feature can be included and when it can be released. I will also specify the donation amount required for this feature to be developed and released by specified deadline.
+
+Note that even one sponsored feature can make me do a new release.
+
+#### 6. Accept or Reject
+You can then accept or reject my donation request:
+```
+I [accept|reject] your donation request and deadline.
+```
+
+Note that if you reject my donation request it doesn't mean that the issue won't be resolved. It just means that it won't be put on the priority list for the next release. It will be treated as any other issue (non sponsored).
+
+If you accept my donation request I will add a label `sponsored` on the issue and forward it for the next stage on [Projects](https://github.com/judge0/judge0/projects) page.
+
+#### 7. Development and Testing
+In the development and testing phase I will sometimes send you links to where you can try the new feature.
+
+For some issues this might not be necessary.
+
+#### 8. Release
+After the development the issue will be closed and the feature will be released in the specified release cycle within agreed deadline.
+
+After the release I expect you to send the agreed donation amount via [PayPal](https://www.patreon.com/hermanzdosilovic) or [Revolut](https://pay.revolut.com/profile/hermancy5). You can also do this after sixth step.
+
+### Notes
+1. Sponsored features **must** stay open-source.
+2. One feature can be sponsored by many sponsors.
+3. One sponsor can sponsor many features.
+
+## Other Types of Sponsorships
+If you have any other suggestions on how you would like to collaborate or support this project, please send me an [email](https://github.com/hermanzdosilovic) or schedule a [meeting](https://judge0.appointlet.com) with me.

TELEMETRY.md

@@ -0,0 +1,36 @@
+# Telemetry
+This document is for those who deploy Judge0 to their own infrastructure and not for those who consume Judge0.
+
+If you just consume Judge0 then you should read the [privacy policy](PRIVACY_POLICY.md).
+
+## Introduction
+Since version v1.6.0 Judge0 is collecting telemetry data which is used to help understand how to improve the product and to better understand how Judge0 is used in various production environments.
+
+Our close-source [telemetry client](bin/telemetry) periodically sends telemetry data to our central telemetry server.
+
+Telemetry reporting is **enabled** by default.
+
+This document describes how to disable telemetry reporting and what data is collected.
+
+## Disabling Telemetry Reporting
+To disable telemetry reporting set variable `JUDGE0_TELEMETRY_ENABLE` to `false` in [judge0.conf](judge0.conf).
+
+## Collected Data
+Every deployed instance of Judge0 with enabled telemetry reporting has its own ID that is used to identify the instance.
+
+### The Data Telemetry Client Sends
+Your instance of Judge0 will send the new telemetry report to our central telemetry server every 12 hours. Following data is send in the report:
+- the ID of your instance and
+- the version of your Judge0 instance
+
+### The Data Telemetry Server Stores
+When the new telemetry report arrives our telemetry server stores the following data:
+- all the data that telemetry clients sends and
+- timestamp when the report was send
+
+IP address of your instance is **not** sent or stored.
+
+Note that only the last report is stored on telemetry server, i.e. the new report overwrites the last report.
+
+## Other Notes and Information
+1. You can disable telemetry reporting at any time but the data from the last report stays stored on the telemetry server.

agricius

@@ -0,0 +1,128 @@
+#!/bin/bash
+#
+# Agricius - build tool for Judge0.
+#
+# Named after Saint Agricius of Trier - protector of carpenters, builders, confectioners, blacksmiths, tailors and butchers.
+
+_err() {
+    echo >&2 "Error: $*"
+}
+
+_die() {
+    _err "$*"
+    exit 1
+}
+
+__get_argument() {
+    if [[ -n "$2" ]] && [[ ${2:0:1} != "-" ]]; then
+        echo "$2"
+    else
+        _err "Argument for $1 is missing."
+    fi
+}
+
+_positional_params=""
+while [[ $# -gt 0 ]]; do
+    case "$1" in
+        --cache-from)
+            _cache="$(__get_argument $1 $2)"; [[ "$_cache" == "" ]] && exit 1
+            shift 2
+            ;;
+        -*|--*)
+            _die "Unknown option $1.
+Usage: $0 [--cache-from image] command
+
+Available commands:
+    build       Build Docker images.
+    publish     Push Docker images to repository. Implies build."
+            ;;
+        *)
+            _positional_params="$_positional_params $1"
+            shift
+            ;;
+    esac
+done
+eval set -- "$_positional_params"
+
+if [[ "$_cache" != "" ]]; then
+    docker pull $_cache
+    _cache="--cache-from $_cache"
+fi
+
+JUDGE0_DOCKER_REPOSITORY=judge0/judge0
+
+JUDGE0_PROJECT_ROOT="$(git rev-parse --show-toplevel)"
+JUDGE0_COMMIT="$(git log -1 --format=%h --abbrev=8)"
+JUDGE0_BRANCH="$(git rev-parse --abbrev-ref HEAD)"
+
+JUDGE0_EDITION="$JUDGE0_BRANCH"
+if [[ "$JUDGE0_BRANCH" == "master" ]]; then
+    JUDGE0_EDITION="standard"
+fi
+
+JUDGE0_EDITION_SLUG="-$JUDGE0_EDITION"
+if [[ "$JUDGE0_EDITION" == "standard" ]]; then
+    JUDGE0_EDITION_SLUG=""
+fi
+
+JUDGE0_VERSION_TAG="$(git tag --points-at HEAD)"
+JUDGE0_VERSION="${JUDGE0_VERSION_TAG:1}" # Remove the "v" the beginning.
+JUDGE0_VERSION="${JUDGE0_VERSION%-*}" # Remove everything else after "-".
+
+JUDGE0_PRODUCTION_IMAGES="$JUDGE0_DOCKER_REPOSITORY:$JUDGE0_COMMIT$JUDGE0_EDITION_SLUG"
+if [[ "$JUDGE0_VERSION" != "" ]]; then
+    JUDGE0_PRODUCTION_IMAGES="$JUDGE0_PRODUCTION_IMAGES $JUDGE0_DOCKER_REPOSITORY:latest$JUDGE0_EDITION_SLUG"
+    JUDGE0_PRODUCTION_IMAGES="$JUDGE0_PRODUCTION_IMAGES $JUDGE0_DOCKER_REPOSITORY:$JUDGE0_VERSION$JUDGE0_EDITION_SLUG"
+fi
+
+JUDGE0_DEVELOPMENT_IMAGES="$JUDGE0_DOCKER_REPOSITORY:$JUDGE0_COMMIT-dev$JUDGE0_EDITION_SLUG"
+if [[ "$JUDGE0_VERSION" != "" ]]; then
+    JUDGE0_DEVELOPMENT_IMAGES="$JUDGE0_DEVELOPMENT_IMAGES $JUDGE0_DOCKER_REPOSITORY:latest$JUDGE0_EDITION_SLUG-dev"
+    JUDGE0_DEVELOPMENT_IMAGES="$JUDGE0_DEVELOPMENT_IMAGES $JUDGE0_DOCKER_REPOSITORY:$JUDGE0_VERSION$JUDGE0_EDITION_SLUG-dev"
+fi
+
+env | grep JUDGE0_ | sort
+
+pushd "$JUDGE0_PROJECT_ROOT"
+
+function build_and_tag() {
+    local _target=$1
+    local _images=($2)
+    local _main_image=${_images[0]}
+
+    set -xe
+    docker build -t $_main_image $_cache --target $_target .
+    set +xe
+
+    for (( i=0; i<${#_images[@]}; i++ )) do
+        docker tag $_main_image ${_images[i]}
+    done
+}
+build_and_tag production "$JUDGE0_PRODUCTION_IMAGES"
+build_and_tag development "$JUDGE0_DEVELOPMENT_IMAGES"
+
+_command="$1"
+if [[ "$_command" == "publish" ]]; then
+    if [[ "$JUDGE0_VERSION" == "" ]]; then
+        _die "Cannot publish untagged version."
+    fi
+    _push_images() {
+        local _images=($1)
+        for (( i=1; i<${#_images[@]}; i++ )) do
+            docker push ${_images[i]}
+        done
+    }
+    _push_images "$JUDGE0_PRODUCTION_IMAGES"
+    _push_images "$JUDGE0_DEVELOPMENT_IMAGES"
+fi
+
+_untag() {
+    local _images=($1)
+    for (( i=0; i<${#_images[@]}-1; i++ )) do
+        docker rmi ${_images[i]}
+    done
+}
+_untag "$JUDGE0_PRODUCTION_IMAGES"
+_untag "$JUDGE0_DEVELOPMENT_IMAGES"
+
+popd

app/channels/application_cable/channel.rb

@@ -0,0 +1,4 @@
+module ApplicationCable
+  class Channel < ActionCable::Channel::Base
+  end
+end

app/channels/application_cable/connection.rb

@@ -0,0 +1,4 @@
+module ApplicationCable
+  class Connection < ActionCable::Connection::Base
+  end
+end

app/controllers/application_controller.rb

@@ -0,0 +1,13 @@
+class ApplicationController < SessionsController
+  private
+
+  def pagination_dict(collection)
+    {
+      current_page: collection.current_page,
+      next_page: collection.next_page,
+      prev_page: collection.previous_page,
+      total_pages: collection.total_pages,
+      total_count: collection.total_entries
+    }
+  end
+end

app/controllers/health_controller.rb

@@ -0,0 +1,27 @@
+class HealthController < ApplicationController
+  def workers
+    Resque.workers.first.try(:prune_dead_workers) if params[:prune_dead_workers] == "true"
+
+    queues = Hash.new { |h, k| h[k] = [] }
+    Resque.workers.each do |worker|
+      worker.queues.each do |queue|
+        queues[queue] << worker
+      end
+    end
+
+    json = []
+    Resque.queues.each do |queue|
+      workers = queues[queue]
+      json << {
+        queue: queue,
+        size: Resque.size(queue),
+        available: workers.count,
+        idle: workers.count { |w| w.idle? },
+        working: workers.count { |w| w.working? },
+        paused: workers.count { |w| w.paused? }
+      }
+    end
+
+    render json: json
+  end
+end

app/controllers/home_controller.rb

@@ -0,0 +1,11 @@
+class HomeController < ActionController::API
+  include ActionView::Layouts
+
+  def index
+    if Config::USE_DOCS_AS_HOMEPAGE
+      render file: Rails.root.join('public/docs.html')
+    else
+      head :ok
+    end
+  end
+end

app/controllers/info_controller.rb

@@ -0,0 +1,98 @@
+class InfoController < ApplicationController
+  @@license ||= File.read("LICENSE")
+  @@isolate ||= `isolate --version`
+
+  def system_info
+    render json: SystemInfo.sys_info
+  end
+
+  def config_info
+    render json: Config.config_info
+  end
+
+  def about
+    render json: {
+      version: ENV["JUDGE0_VERSION"],
+      homepage: ENV["JUDGE0_HOMEPAGE"],
+      source_code: ENV["JUDGE0_SOURCE_CODE"],
+      maintainer: ENV["JUDGE0_MAINTAINER"]
+    }
+  end
+
+  def version
+    render plain: ENV["JUDGE0_VERSION"]
+  end
+
+  def license
+    render plain: @@license
+  end
+
+  def isolate
+    render plain: @@isolate
+  end
+
+  def statistics
+    Rails.cache.delete("statistics") if params[:invalidate_cache] == "true"
+    @@cache_duration ||= 10.minutes
+    render json: Rails.cache.fetch("statistics", expires_in: @@cache_duration) {
+      @@language_name ||= Hash[Language.unscoped.pluck(:id, :name)]
+
+      count_by_language = []
+      Submission.unscoped.group(:language_id).count.each do |language_id, count|
+        count_by_language << {
+          language: {
+            id: language_id,
+            name: @@language_name[language_id]
+          },
+          count: count
+        }
+      end
+      count_by_language = count_by_language.sort_by { |x| x[:count] }.reverse
+
+      count_by_status = []
+      Submission.unscoped.group(:status_id).count.each do |status_id, count|
+        count_by_status << {
+          status: {
+            id: status_id,
+            name: Status.find_by(id: status_id).name # Not a SQL query!
+          },
+          count: count
+        }
+      end
+      count_by_status = count_by_status.sort_by{ |x| x[:count] }.reverse
+
+      now = DateTime.now
+      today = DateTime.now.beginning_of_day.to_date
+      last_30_days = Submission.unscoped.group("created_at::DATE").where("created_at::DATE >= ?", today - 30).count
+      last_30_days[today] ||= 0
+      last_30_days_result = {}
+      (today-30...today).each do |day|
+        last_30_days_result[day.to_date] = last_30_days[day] || 0
+      end
+      last_30_days_result = last_30_days_result.sort.reverse.to_h
+
+      database_size = ActiveRecord::Base.connection.execute(
+        "SELECT
+          pg_size_pretty(pg_database_size('#{ENV['POSTGRES_DB']}')) AS size_pretty,
+          pg_database_size('#{ENV['POSTGRES_DB']}') AS size_in_bytes
+        "
+      ).to_a[0]
+
+      {
+        created_at: now,
+        cached_until: now + @@cache_duration,
+        submissions: {
+          total: Submission.count,
+          today: last_30_days[today],
+          last_30_days: last_30_days_result
+        },
+        languages: count_by_language,
+        statuses: count_by_status,
+        database: {
+          size_pretty: database_size["size_pretty"],
+          size_in_bytes: database_size["size_in_bytes"]
+        }
+      }
+    }
+  end
+end

app/controllers/languages_controller.rb

@@ -0,0 +1,13 @@
+class LanguagesController < ApplicationController
+  def index
+    render json: Language.all, each_serializer: LanguageSerializer, fields: [:id, :name]
+  end
+
+  def all
+    render json: Language.unscoped.order(name: :asc), each_serializer: LanguageSerializer, fields: [:id, :name, :is_archived]
+  end
+
+  def show
+    render json: Language.unscoped.find(params[:id])
+  end
+end

app/controllers/sessions_controller.rb

@@ -0,0 +1,51 @@
+class SessionsController < ActionController::API
+  before_action :verify_ip_address
+  before_action :authenticate_request
+  before_action :authorize_request, only: [:authorize]
+
+  def authenticate
+    head :ok
+  end
+
+  def authorize
+    head :ok
+  end
+
+  private
+
+  def verify_ip_address
+    @@disallowed_ip_addresses ||= ENV['DISALLOW_IP'].to_s.split - ENV['ALLOW_IP'].to_s.split
+    @@allowed_ip_addresses ||= ENV['ALLOW_IP'].to_s.split - ENV['DISALLOW_IP'].to_s.split
+    head :forbidden if @@disallowed_ip_addresses.include?(request.remote_ip)
+    head :forbidden if @@allowed_ip_addresses.present? && !@@allowed_ip_addresses.include?(request.remote_ip)
+  end
+
+  def authenticate_request
+    head :unauthorized if safe_compare(Rails.application.secrets.authn_token, Rails.application.secrets.authn_header)
+  end
+
+  def authorize_request
+    head :forbidden unless Rails.application.secrets.authz_token.present?
+    head :forbidden if safe_compare(Rails.application.secrets.authz_token, Rails.application.secrets.authz_header)
+  end
+
+  def check_maintenance
+    @@maintenance_message ||= ENV['MAINTENANCE_MESSAGE']
+    if Config::MAINTENANCE_MODE
+      render json: {
+        error: @@maintenance_message
+      }, status: :service_unavailable
+    end
+  end
+
+  def safe_compare(token, header)
+    token = token.to_s
+    header = header.to_s
+    return false unless token.present?
+    provided_token = (request.headers[header] || params[header]).to_s
+    token.split.each do |value|
+      return false if ActiveSupport::SecurityUtils.secure_compare(value, provided_token)
+    end
+    true
+  end
+end

app/controllers/statuses_controller.rb

@@ -0,0 +1,5 @@
+class StatusesController < ApplicationController
+  def index
+    render json: Status.all, each_serializer: StatusSerializer
+  end
+end

app/controllers/submissions_controller.rb

@@ -0,0 +1,236 @@
+class SubmissionsController < ApplicationController
+  before_action :authorize_request, only: [:index, :destroy]
+  before_action :check_maintenance, only: [:create, :destroy]
+  before_action :check_wait, only: [:create] # Wait in batch_create is not allowed
+  before_action :check_batched_submissions, only: [:batch_create, :batch_show]
+  before_action :check_queue_size, only: [:create, :batch_create]
+  before_action :check_requested_fields, except: [:batch_create] # Fields are ignored in batch_create
+  before_action :set_base64_encoded
+
+  def index
+    page = params[:page].try(:to_i) || 1
+    per_page = params[:per_page].try(:to_i) || Submission.per_page
+
+    if page <= 0
+      render json: { error: "invalid page: #{page}" }, status: :bad_request
+      return
+    elsif per_page < 0
+      render json: { error: "invalid per_page: #{per_page}" }, status: :bad_request
+      return
+    end
+
+    submissions = Submission.paginate(page: page, per_page: per_page)
+    serializable_submissions = ActiveModelSerializers::SerializableResource.new(
+      submissions, { each_serializer: SubmissionSerializer, base64_encoded: @base64_encoded, fields: @requested_fields }
+    )
+
+    render json: {
+      submissions: serializable_submissions.as_json,
+      meta: pagination_dict(submissions)
+    }
+  rescue Encoding::UndefinedConversionError => e
+    render json: {
+      error: "some attributes for one or more submissions cannot be converted to UTF-8, use base64_encoded=true query parameter"
+    }, status: :bad_request
+  end
+
+  def destroy
+    if !Config::ENABLE_SUBMISSION_DELETE
+      render json: { error: "delete not allowed" }, status: :bad_request
+      return
+    end
+
+    submission = Submission.find_by!(token: params[:token])
+    if submission.status == Status.queue || submission.status == Status.process
+      render json: {
+        error: "submission cannot be deleted because its status is #{submission.status.id} (#{submission.status.name})"
+      }, status: :bad_request
+      return
+    end
+
+    submission.delete
+
+    # Forcing base64_encoded=true because it guarantees user will get requested data after delete.
+    render json: submission, base64_encoded: true, fields: @requested_fields
+  end
+
+  def show
+    token = params[:token]
+    render json: Rails.cache.fetch("#{token}", expires_in: Config::SUBMISSION_CACHE_DURATION, race_condition_ttl: 0.1*Config::SUBMISSION_CACHE_DURATION) {
+      Submission.find_by!(token: token)
+    }, base64_encoded: @base64_encoded, fields: @requested_fields
+  rescue Encoding::UndefinedConversionError
+    render_conversion_error(:bad_request)
+  end
+
+  def batch_show
+    tokens = (request.headers[:tokens] || params[:tokens]).to_s.strip.split(",")
+
+    if tokens.length > Config::MAX_SUBMISSION_BATCH_SIZE
+      render json: {
+        error: "number of submissions in a batch should be less than or equal to #{Config::MAX_SUBMISSION_BATCH_SIZE}"
+      }, status: :bad_request
+      return
+    elsif tokens.length == 0
+      render json: {
+        error: "there should be at least one submission in a batch"
+      }, status: :bad_request
+      return
+    end
+
+    existing_submissions = Hash[Submission.where(token: tokens).collect{ |s| [s.token, s] }]
+
+    submissions = []
+    tokens.each do |token|
+      if existing_submissions.has_key?(token)
+        serialized_submission  = ActiveModelSerializers::SerializableResource.new(
+          existing_submissions[token], { serializer: SubmissionSerializer, base64_encoded: @base64_encoded, fields: @requested_fields }
+        )
+        submissions << serialized_submission.as_json
+      else
+        submissions << nil
+      end
+    end
+
+    render json: { submissions: submissions }
+  rescue Encoding::UndefinedConversionError => e
+    render json: {
+      error: "some attributes for one or more submissions cannot be converted to UTF-8, use base64_encoded=true query parameter"
+    }, status: :bad_request
+  end
+
+  def create
+    submission = Submission.new(submission_params(params))
+
+    if submission.save
+      if @wait
+        begin
+          IsolateRunner.perform_now(submission)
+          submission.reload
+          render json: submission, status: :created, base64_encoded: @base64_encoded, fields: @requested_fields
+        rescue Encoding::UndefinedConversionError => e
+          render_conversion_error(:created, submission.token)
+        end
+      else
+        IsolateRunner.perform_later(submission)
+        render json: submission, status: :created, fields: [:token]
+      end
+    else
+      render json: submission.errors, status: :unprocessable_entity
+    end
+  end
+
+  # Batch Create does not support sync (wait=true) mode.
+  def batch_create
+    number_of_submissions = params[:submissions].try(:size).to_i
+
+    if number_of_submissions > Config::MAX_SUBMISSION_BATCH_SIZE
+      render json: {
+        error: "number of submissions in a batch should be less than or equal to #{Config::MAX_SUBMISSION_BATCH_SIZE}"
+      }, status: :bad_request
+      return
+    elsif number_of_submissions == 0
+      render json: {
+        error: "there should be at least one submission in a batch"
+      }, status: :bad_request
+      return
+    end
+
+    submissions = params[:submissions].each.collect{ |p| Submission.new(submission_params(p)) }
+
+    response = []
+    has_valid_submission = false
+
+    submissions.each do |submission|
+      if submission.save
+        IsolateRunner.perform_later(submission)
+        response << { token: submission.token }
+        has_valid_submission = true
+      else
+        response << submission.errors
+      end
+    end
+
+    render json: response, status: has_valid_submission ? :created : :unprocessable_entity
+  end
+
+  private
+
+  def submission_params(params)
+    submission_params = params.permit(
+      :source_code,
+      :language_id,
+      :compiler_options,
+      :command_line_arguments,
+      :number_of_runs,
+      :stdin,
+      :expected_output,
+      :cpu_time_limit,
+      :cpu_extra_time,
+      :wall_time_limit,
+      :memory_limit,
+      :stack_limit,
+      :max_processes_and_or_threads,
+      :enable_per_process_and_thread_time_limit,
+      :enable_per_process_and_thread_memory_limit,
+      :max_file_size,
+      :redirect_stderr_to_stdout,
+      :callback_url,
+      :additional_files,
+      :enable_network
+    )
+
+    submission_params[:additional_files] = Base64Service.decode(submission_params[:additional_files])
+
+    if @base64_encoded
+      submission_params[:source_code] = Base64Service.decode(submission_params[:source_code])
+      submission_params[:stdin] = Base64Service.decode(submission_params[:stdin])
+      submission_params[:expected_output] = Base64Service.decode(submission_params[:expected_output])
+    end
+
+    submission_params
+  end
+
+  def check_wait
+    @wait = params[:wait] == "true"
+    if @wait && !Config::ENABLE_WAIT_RESULT
+      render json: { error: "wait not allowed" }, status: :bad_request
+    end
+  end
+
+  def check_batched_submissions
+    unless Config::ENABLE_BATCHED_SUBMISSIONS
+      render json: { error: "batched submissions are not allowed" }, status: :bad_request
+    end
+  end
+
+  def check_queue_size
+    number_of_submissions = params[:submissions].try(:size).presence || 1
+    if Resque.size(ENV["JUDGE0_VERSION"]) + number_of_submissions > Config::MAX_QUEUE_SIZE
+      render json: { error: "queue is full" }, status: :service_unavailable
+    end
+  end
+
+  def check_requested_fields
+    fields_service = Fields::Submission.new(params[:fields])
+    render json: { error: "invalid fields: [#{fields_service.invalid_fields.join(", ")}]" }, status: :bad_request if fields_service.has_invalid_fields?
+    @requested_fields = fields_service.requested_fields
+  end
+
+  def set_base64_encoded
+    if Config::DISABLE_IMPLICIT_BASE64_ENCODING
+      @base64_encoded = params[:base64_encoded] == "true"
+    else
+      @base64_encoded = params[:base64_encoded] != "false"
+    end
+  end
+
+  def render_conversion_error(status, token = nil)
+    response_json = {
+      error: "some attributes for this submission cannot be converted to UTF-8, use base64_encoded=true query parameter",
+    }
+    response_json[:token] = token if token
+
+    render json: response_json, status: status
+  end
+end

app/enumerations/status.rb

@@ -0,0 +1,30 @@
+class Status < Enumerations::Base
+  values queue:     { id:  1, name: 'In Queue' },
+         process:   { id:  2, name: 'Processing' },
+         ac:        { id:  3, name: 'Accepted' },
+         wa:        { id:  4, name: 'Wrong Answer' },
+         tle:       { id:  5, name: 'Time Limit Exceeded' },
+         ce:        { id:  6, name: 'Compilation Error' },
+         sigsegv:   { id:  7, name: 'Runtime Error (SIGSEGV)' },
+         sigxfsz:   { id:  8, name: 'Runtime Error (SIGXFSZ)' },
+         sigfpe:    { id:  9, name: 'Runtime Error (SIGFPE)' },
+         sigabrt:   { id: 10, name: 'Runtime Error (SIGABRT)' },
+         nzec:      { id: 11, name: 'Runtime Error (NZEC)' },
+         other:     { id: 12, name: 'Runtime Error (Other)' },
+         boxerr:    { id: 13, name: 'Internal Error' },
+         exeerr:    { id: 14, name: 'Exec Format Error' }
+
+  def self.find_runtime_error_by_status_code(status_code)
+    case status_code.to_i
+      when 11 then Status.sigsegv
+      when 25 then Status.sigxfsz
+      when 8  then Status.sigfpe
+      when 6  then Status.sigabrt
+      else Status.other
+    end
+  end
+
+  def self.model_name
+    @@model_name ||= ActiveModel::Name.new(self)
+  end
+end

app/helpers/config.rb

@@ -0,0 +1,90 @@
+module Config
+  # For more info read:
+  # https://github.com/judge0/judge0/blob/master/judge0.conf
+
+  MAINTENANCE_MODE = ENV["MAINTENANCE_MODE"] == "true"
+  ENABLE_WAIT_RESULT = ENV["ENABLE_WAIT_RESULT"] != "false"
+  ENABLE_COMPILER_OPTIONS = ENV["ENABLE_COMPILER_OPTIONS"] != "false"
+  ALLOWED_LANGUAGES_FOR_COMPILER_OPTIONS = ENV["ALLOWED_LANGUAGES_FOR_COMPILER_OPTIONS"].to_s.strip.split
+  ENABLE_COMMAND_LINE_ARGUMENTS = ENV["ENABLE_COMMAND_LINE_ARGUMENTS"] != "false"
+  ENABLE_SUBMISSION_DELETE = ENV["ENABLE_SUBMISSION_DELETE"] == "true"
+  ENABLE_CALLBACKS = ENV["ENABLE_CALLBACKS"] != "false"
+  CALLBACKS_MAX_TRIES = (ENV["CALLBACKS_MAX_TRIES"].presence || 3).to_i
+  CALLBACKS_TIMEOUT = (ENV["CALLBACKS_TIMEOUT"].presence || 5).to_f
+  ENABLE_ADDITIONAL_FILES = ENV["ENABLE_ADDITIONAL_FILES"] != "false"
+  MAX_QUEUE_SIZE = (ENV["MAX_QUEUE_SIZE"].presence || 100).to_i
+  CPU_TIME_LIMIT = (ENV["CPU_TIME_LIMIT"].presence || 5).to_f
+  MAX_CPU_TIME_LIMIT = (ENV["MAX_CPU_TIME_LIMIT"].presence || 15).to_f
+  CPU_EXTRA_TIME = (ENV["CPU_EXTRA_TIME"].presence || 1).to_f
+  MAX_CPU_EXTRA_TIME = (ENV["MAX_CPU_EXTRA_TIME"].presence || 5).to_f
+  WALL_TIME_LIMIT = (ENV["WALL_TIME_LIMIT"].presence || 10).to_f
+  MAX_WALL_TIME_LIMIT = (ENV["MAX_WALL_TIME_LIMIT"].presence || 20).to_f
+  MEMORY_LIMIT = (ENV["MEMORY_LIMIT"].presence || 128000).to_i # in KB
+  MAX_MEMORY_LIMIT = (ENV["MAX_MEMORY_LIMIT"].presence || 512000).to_i
+  STACK_LIMIT = (ENV["STACK_LIMIT"].presence || 64000).to_i # in KB
+  MAX_STACK_LIMIT = (ENV["MAX_STACK_LIMIT"].presence || 128000).to_i
+  MAX_PROCESSES_AND_OR_THREADS = (ENV["MAX_PROCESSES_AND_OR_THREADS"].presence || 60).to_i
+  MAX_MAX_PROCESSES_AND_OR_THREADS = (ENV["MAX_MAX_PROCESSES_AND_OR_THREADS"].presence || 120).to_i
+  ENABLE_PER_PROCESS_AND_THREAD_TIME_LIMIT = ENV["ENABLE_PER_PROCESS_AND_THREAD_TIME_LIMIT"] == "true"
+  ALLOW_ENABLE_PER_PROCESS_AND_THREAD_TIME_LIMIT = ENV["ALLOW_ENABLE_PER_PROCESS_AND_THREAD_TIME_LIMIT"] != "false"
+  ENABLE_PER_PROCESS_AND_THREAD_MEMORY_LIMIT = ENV["ENABLE_PER_PROCESS_AND_THREAD_MEMORY_LIMIT"] == "true"
+  ALLOW_ENABLE_PER_PROCESS_AND_THREAD_MEMORY_LIMIT = ENV["ALLOW_ENABLE_PER_PROCESS_AND_THREAD_MEMORY_LIMIT"] != "false"
+  MAX_FILE_SIZE = (ENV["MAX_FILE_SIZE"].presence || 1024).to_i
+  MAX_MAX_FILE_SIZE = (ENV["MAX_MAX_FILE_SIZE"].presence || 4096).to_i
+  NUMBER_OF_RUNS = (ENV["NUMBER_OF_RUNS"].presence || 1).to_i
+  MAX_NUMBER_OF_RUNS = (ENV["MAX_NUMBER_OF_RUNS"].presence || 20).to_i
+  REDIRECT_STDERR_TO_STDOUT = ENV["REDIRECT_STDERR_TO_STDOUT"] == "true"
+  MAX_EXTRACT_SIZE = (ENV["MAX_EXTRACT_SIZE"].presence || 10240).to_i
+  ENABLE_BATCHED_SUBMISSIONS = ENV["ENABLE_BATCHED_SUBMISSIONS"] != "false"
+  MAX_SUBMISSION_BATCH_SIZE = (ENV["MAX_SUBMISSION_BATCH_SIZE"].presence || 20).to_i
+  SUBMISSION_CACHE_DURATION = (ENV["SUBMISSION_CACHE_DURATION"].presence || 1).to_f
+  USE_DOCS_AS_HOMEPAGE = ENV["USE_DOCS_AS_HOMEPAGE"] == "true"
+  ALLOW_ENABLE_NETWORK = ENV["ALLOW_ENABLE_NETWORK"] != "false"
+  ENABLE_NETWORK = ENV["ENABLE_NETWORK"] == "true"
+  DISABLE_IMPLICIT_BASE64_ENCODING = ENV["DISABLE_IMPLICIT_BASE64_ENCODING"] == "true"
+
+  def self.config_info
+    @@default_confg ||= {
+      "maintenance_mode": MAINTENANCE_MODE,
+      "enable_wait_result": ENABLE_WAIT_RESULT,
+      "enable_compiler_options": ENABLE_COMPILER_OPTIONS,
+      "allowed_languages_for_compile_options": ALLOWED_LANGUAGES_FOR_COMPILER_OPTIONS,
+      "enable_command_line_arguments": ENABLE_COMMAND_LINE_ARGUMENTS,
+      "enable_submission_delete": ENABLE_SUBMISSION_DELETE,
+      "enable_callbacks": ENABLE_CALLBACKS,
+      "callbacks_max_tries": CALLBACKS_MAX_TRIES,
+      "callbacks_timeout": CALLBACKS_TIMEOUT,
+      "enable_additional_files": ENABLE_ADDITIONAL_FILES,
+      "max_queue_size": MAX_QUEUE_SIZE,
+      "cpu_time_limit": CPU_TIME_LIMIT,
+      "max_cpu_time_limit": MAX_CPU_TIME_LIMIT,
+      "cpu_extra_time": CPU_EXTRA_TIME,
+      "max_cpu_extra_time": MAX_CPU_EXTRA_TIME,
+      "wall_time_limit": WALL_TIME_LIMIT,
+      "max_wall_time_limit": MAX_WALL_TIME_LIMIT,
+      "memory_limit": MEMORY_LIMIT,
+      "max_memory_limit": MAX_MEMORY_LIMIT,
+      "stack_limit": STACK_LIMIT,
+      "max_stack_limit": MAX_STACK_LIMIT,
+      "max_processes_and_or_threads": MAX_PROCESSES_AND_OR_THREADS,
+      "max_max_processes_and_or_threads": MAX_MAX_PROCESSES_AND_OR_THREADS,
+      "enable_per_process_and_thread_time_limit": ENABLE_PER_PROCESS_AND_THREAD_TIME_LIMIT,
+      "allow_enable_per_process_and_thread_time_limit": ALLOW_ENABLE_PER_PROCESS_AND_THREAD_TIME_LIMIT,
+      "enable_per_process_and_thread_memory_limit": ENABLE_PER_PROCESS_AND_THREAD_MEMORY_LIMIT,
+      "allow_enable_per_process_and_thread_memory_limit": ALLOW_ENABLE_PER_PROCESS_AND_THREAD_MEMORY_LIMIT,
+      "max_file_size": MAX_FILE_SIZE,
+      "max_max_file_size": MAX_MAX_FILE_SIZE,
+      "number_of_runs": NUMBER_OF_RUNS,
+      "max_number_of_runs": MAX_NUMBER_OF_RUNS,
+      "redirect_stderr_to_stdout": REDIRECT_STDERR_TO_STDOUT,
+      "max_extract_size": MAX_EXTRACT_SIZE,
+      "enable_batched_submissions": ENABLE_BATCHED_SUBMISSIONS,
+      "max_submission_batch_size": MAX_SUBMISSION_BATCH_SIZE,
+      "submission_cache_duration": SUBMISSION_CACHE_DURATION,
+      "use_docs_as_homepage": USE_DOCS_AS_HOMEPAGE,
+      "allow_enable_network": ALLOW_ENABLE_NETWORK,
+      "enable_network": ENABLE_NETWORK,
+      "disable_implicit_base64_encoding": DISABLE_IMPLICIT_BASE64_ENCODING
+    }
+  end
+end

app/helpers/isolate_runner.rb

@@ -0,0 +1,39 @@
+module IsolateRunner
+  MAX_WAIT_TIME_S = 600
+
+  INITIAL_WAIT_TIME_S = 2
+  NEXT_WAIT_TIME_S = 1
+  WAIT_TIME_FACTOR_S = 0.5
+
+  WAITING_STATUSES = [Status.queue.id, Status.process.id, nil]
+
+  def self.perform_now(submission)
+    IsolateRunner.perform_later(submission)
+
+    submission_id = submission.id
+
+    total_wait_time = 0
+    (0..).each do |i|
+      break if total_wait_time >= MAX_WAIT_TIME_S
+
+      if i == 0 then
+        wait_time = INITIAL_WAIT_TIME_S
+      elsif i == 1 then
+        wait_time = NEXT_WAIT_TIME_S
+      else
+        wait_time = WAIT_TIME_FACTOR_S * i
+      end
+
+      sleep(wait_time)
+
+      total_wait_time += wait_time
+
+      break if !WAITING_STATUSES.include?(Submission.where(id: submission_id).pluck(:status_id).first)
+    end
+  end
+
+  def self.perform_later(submission)
+    submission.update(status: Status.queue, queued_at: DateTime.now, queue_host: ENV["HOSTNAME"])
+    IsolateJob.perform_later(submission.id)
+  end
+end

app/helpers/nil_value.rb

@@ -0,0 +1,6 @@
+module NilValue
+    def self.value_or_default(value, default)
+        return value unless value == nil
+        return default
+    end
+end

app/helpers/system_info.rb

@@ -0,0 +1,13 @@
+module SystemInfo
+  def self.sys_info
+    @@sys_info ||= self.cpu_info.merge(self.mem_info)
+  end
+
+  def self.cpu_info #sorryforthisline
+    @@cpu_info ||=  Hash[`lscpu`.split("\n").collect{|l| l = l.split(":"); [l[0].strip, l[1].strip]}]
+  end
+
+  def self.mem_info #sorryagain #itjustworks
+    @@mem_info ||= Hash[`free -h`.split("\n")[1..-1].collect{|l| l = l.split(":"); [l[0].strip, l[1].split(" ")[0].strip]}].without("-/+ buffers/cache")
+  end
+end

app/jobs/application_job.rb

@@ -0,0 +1,2 @@
+class ApplicationJob < ActiveJob::Base
+end

app/jobs/isolate_job.rb

@@ -0,0 +1,371 @@
+class IsolateJob < ApplicationJob
+  retry_on RuntimeError, wait: 0.1.seconds, attempts: 100
+
+  queue_as ENV["JUDGE0_VERSION"].to_sym
+
+  STDIN_FILE_NAME = "stdin.txt"
+  STDOUT_FILE_NAME = "stdout.txt"
+  STDERR_FILE_NAME = "stderr.txt"
+  METADATA_FILE_NAME = "metadata.txt"
+  ADDITIONAL_FILES_ARCHIVE_FILE_NAME = "additional_files.zip"
+
+  attr_reader :submission, :cgroups,
+              :box_id, :workdir, :boxdir, :tmpdir,
+              :source_file, :stdin_file, :stdout_file,
+              :stderr_file, :metadata_file, :additional_files_archive_file
+
+  def perform(submission_id)
+    @submission = Submission.find(submission_id)
+    submission.update(status: Status.process, started_at: DateTime.now, execution_host: ENV["HOSTNAME"])
+
+    time = []
+    memory = []
+
+    submission.number_of_runs.times do
+      initialize_workdir
+      if compile == :failure
+        cleanup
+        return
+      end
+      run
+      verify
+
+      time << submission.time
+      memory << submission.memory
+
+      cleanup
+      break if submission.status != Status.ac
+    end
+
+    submission.time = time.inject(&:+).to_f / time.size
+    submission.memory = memory.inject(&:+).to_f / memory.size
+    submission.save
+
+  rescue Exception => e
+    raise e.message unless submission
+    submission.update(message: e.message, status: Status.boxerr, finished_at: DateTime.now)
+    cleanup(raise_exception = false)
+  ensure
+    call_callback
+  end
+
+  private
+
+  def initialize_workdir
+    @box_id = submission.id%2147483647
+    @cgroups = (!submission.enable_per_process_and_thread_time_limit || !submission.enable_per_process_and_thread_memory_limit) ? "--cg" : ""
+    @workdir = `isolate #{cgroups} -b #{box_id} --init`.chomp
+    @boxdir = workdir + "/box"
+    @tmpdir = workdir + "/tmp"
+    @source_file = boxdir + "/" + submission.language.source_file.to_s
+    @stdin_file = workdir + "/" + STDIN_FILE_NAME
+    @stdout_file = workdir + "/" + STDOUT_FILE_NAME
+    @stderr_file = workdir + "/" + STDERR_FILE_NAME
+    @metadata_file = workdir + "/" + METADATA_FILE_NAME
+    @additional_files_archive_file = boxdir + "/" + ADDITIONAL_FILES_ARCHIVE_FILE_NAME
+
+    [stdin_file, stdout_file, stderr_file, metadata_file].each do |f|
+      initialize_file(f)
+    end
+
+    File.open(source_file, "wb") { |f| f.write(submission.source_code) } unless submission.is_project
+    File.open(stdin_file, "wb") { |f| f.write(submission.stdin) }
+
+    extract_archive
+  end
+
+  def initialize_file(file)
+    `sudo touch #{file} && sudo chown $(whoami): #{file}`
+  end
+
+  def extract_archive
+    return unless submission.additional_files?
+
+    File.open(additional_files_archive_file, "wb") { |f| f.write(submission.additional_files) }
+
+    command = "isolate #{cgroups} \
+    -s \
+    -b #{box_id} \
+    --stderr-to-stdout \
+    -t 2 \
+    -x 1 \
+    -w 4 \
+    -k #{Config::MAX_STACK_LIMIT} \
+    -p#{Config::MAX_MAX_PROCESSES_AND_OR_THREADS} \
+    #{submission.enable_per_process_and_thread_time_limit ? (cgroups.present? ? "--no-cg-timing" : "") : "--cg-timing"} \
+    #{submission.enable_per_process_and_thread_memory_limit ? "-m " : "--cg-mem="}#{Config::MAX_MEMORY_LIMIT} \
+    -f #{Config::MAX_EXTRACT_SIZE} \
+    --run \
+    -- /usr/bin/unzip -n -qq #{ADDITIONAL_FILES_ARCHIVE_FILE_NAME} \
+    "
+
+    puts "[#{DateTime.now}] Extracting archive for submission #{submission.token} (#{submission.id}):"
+    puts command.gsub(/\s+/, " ")
+    puts
+
+    `#{command}`
+
+    File.delete(additional_files_archive_file)
+  end
+
+  def compile
+    unless submission.is_project
+      return :success unless submission.language.compile_cmd
+    end
+
+    compile_script = boxdir + "/" + "compile.sh"
+
+    acceptable_project_compile_scripts = [compile_script, boxdir + "/" + "compile"]
+    if submission.is_project
+      compile_file_exists = false
+      acceptable_project_compile_scripts.each do |f|
+        if File.file?(f)
+          compile_script = f
+          compile_file_exists = true
+          break
+        end
+      end
+
+      unless compile_file_exists
+        return :success # If compile script does not exist then this project does not need to be compiled.
+      end
+    else
+      # gsub can be skipped if compile script is used, but is kept for additional security.
+      compiler_options = submission.compiler_options.to_s.strip.encode("UTF-8", invalid: :replace).gsub(/[$&;<>|`]/, "")
+      File.open(compile_script, "w") { |f| f.write("#{submission.language.compile_cmd % compiler_options}") }
+    end
+
+    compile_output_file = workdir + "/" + "compile_output.txt"
+    initialize_file(compile_output_file)
+
+    command = "isolate #{cgroups} \
+    -s \
+    -b #{box_id} \
+    -M #{metadata_file} \
+    --stderr-to-stdout \
+    -i /dev/null \
+    -t #{Config::MAX_CPU_TIME_LIMIT} \
+    -x 0 \
+    -w #{Config::MAX_WALL_TIME_LIMIT} \
+    -k #{Config::MAX_STACK_LIMIT} \
+    -p#{Config::MAX_MAX_PROCESSES_AND_OR_THREADS} \
+    #{submission.enable_per_process_and_thread_time_limit ? (cgroups.present? ? "--no-cg-timing" : "") : "--cg-timing"} \
+    #{submission.enable_per_process_and_thread_memory_limit ? "-m " : "--cg-mem="}#{Config::MAX_MEMORY_LIMIT} \
+    -f #{Config::MAX_MAX_FILE_SIZE} \
+    -E HOME=/tmp \
+    -E PATH=\"/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin\" \
+    -E LANG -E LANGUAGE -E LC_ALL -E JUDGE0_HOMEPAGE -E JUDGE0_SOURCE_CODE -E JUDGE0_MAINTAINER -E JUDGE0_VERSION \
+    -d /etc:noexec \
+    --run \
+    -- /bin/bash $(basename #{compile_script}) > #{compile_output_file} \
+    "
+
+    puts "[#{DateTime.now}] Compiling submission #{submission.token} (#{submission.id}):"
+    puts command.gsub(/\s+/, " ")
+    puts
+
+    `#{command}`
+    process_status = $?
+
+    compile_output = File.read(compile_output_file)
+    compile_output = nil if compile_output.empty?
+    submission.compile_output = compile_output
+
+    metadata = get_metadata
+
+    reset_metadata_file
+
+    files_to_remove = [compile_output_file]
+    files_to_remove << compile_script unless submission.is_project
+    files_to_remove.each do |f|
+      `sudo rm -rf #{f}`
+    end
+
+    return :success if process_status.success?
+
+    if metadata[:status] == "TO"
+      submission.compile_output = "Compilation time limit exceeded."
+    end
+
+    submission.finished_at = DateTime.now
+    submission.time = nil
+    submission.wall_time = nil
+    submission.memory = nil
+    submission.stdout = nil
+    submission.stderr = nil
+    submission.exit_code = nil
+    submission.exit_signal = nil
+    submission.message = nil
+    submission.status = Status.ce
+    submission.save
+
+    return :failure
+  end
+
+  def run
+    run_script = boxdir + "/" + "run.sh"
+
+    acceptable_project_run_scripts = [run_script, boxdir + "/" + "run"]
+    acceptable_project_run_scripts.each do |f|
+      if File.file?(f)
+        run_script = f
+        break
+      end
+    end
+
+    unless submission.is_project
+      # gsub is mandatory!
+      command_line_arguments = submission.command_line_arguments.to_s.strip.encode("UTF-8", invalid: :replace).gsub(/[$&;<>|`]/, "")
+      File.open(run_script, "w") { |f| f.write("#{submission.language.run_cmd} #{command_line_arguments}")}
+    end
+
+    command = "isolate #{cgroups} \
+    -s \
+    -b #{box_id} \
+    -M #{metadata_file} \
+    #{submission.redirect_stderr_to_stdout ? "--stderr-to-stdout" : ""} \
+    #{submission.enable_network ? "--share-net" : ""} \
+    -t #{submission.cpu_time_limit} \
+    -x #{submission.cpu_extra_time} \
+    -w #{submission.wall_time_limit} \
+    -k #{submission.stack_limit} \
+    -p#{submission.max_processes_and_or_threads} \
+    #{submission.enable_per_process_and_thread_time_limit ? (cgroups.present? ? "--no-cg-timing" : "") : "--cg-timing"} \
+    #{submission.enable_per_process_and_thread_memory_limit ? "-m " : "--cg-mem="}#{submission.memory_limit} \
+    -f #{submission.max_file_size} \
+    -E HOME=/tmp \
+    -E PATH=\"/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin\" \
+    -E LANG -E LANGUAGE -E LC_ALL -E JUDGE0_HOMEPAGE -E JUDGE0_SOURCE_CODE -E JUDGE0_MAINTAINER -E JUDGE0_VERSION \
+    -d /etc:noexec \
+    --run \
+    -- /bin/bash $(basename #{run_script}) \
+    < #{stdin_file} > #{stdout_file} 2> #{stderr_file} \
+    "
+
+    puts "[#{DateTime.now}] Running submission #{submission.token} (#{submission.id}):"
+    puts command.gsub(/\s+/, " ")
+    puts
+
+    `#{command}`
+
+    `sudo rm #{run_script}` unless submission.is_project
+  end
+
+  def verify
+    submission.finished_at = DateTime.now
+
+    metadata = get_metadata
+
+    program_stdout = File.read(stdout_file)
+    program_stdout = nil if program_stdout.empty?
+
+    program_stderr = File.read(stderr_file)
+    program_stderr = nil if program_stderr.empty?
+
+    submission.time = metadata[:time]
+    submission.wall_time = metadata[:"time-wall"]
+    submission.memory = (cgroups.present? ? metadata[:"cg-mem"] : metadata[:"max-rss"])
+    submission.stdout = program_stdout
+    submission.stderr = program_stderr
+    submission.exit_code = metadata[:exitcode].try(:to_i) || 0
+    submission.exit_signal = metadata[:exitsig].try(:to_i)
+    submission.message = metadata[:message]
+    submission.status = determine_status(metadata[:status], submission.exit_signal)
+
+    # After adding support for compiler_options and command_line_arguments
+    # status "Exec Format Error" will no longer occur because compile and run
+    # is done inside a dynamically created bash script, thus isolate doesn't call
+    # execve directily on submission.language.compile_cmd or submission.langauge.run_cmd.
+    # Consequence of running compile and run through bash script is that when
+    # target binary is not found then submission gets status "Runtime Error (NZEC)".
+    #
+    # I think this is for now O.K. behaviour, but I will leave this if block
+    # here until I am 100% sure that "Exec Format Error" can be deprecated.
+    if submission.status == Status.boxerr &&
+       (
+         submission.message.to_s.match(/^execve\(.+\): Exec format error$/) ||
+         submission.message.to_s.match(/^execve\(.+\): No such file or directory$/) ||
+         submission.message.to_s.match(/^execve\(.+\): Permission denied$/)
+       )
+       submission.status = Status.exeerr
+    end
+  end
+
+  def cleanup(raise_exception = true)
+    fix_permissions
+    `sudo rm -rf #{boxdir}/* #{tmpdir}/*`
+    [stdin_file, stdout_file, stderr_file, metadata_file].each do |f|
+      `sudo rm -rf #{f}`
+    end
+    `isolate #{cgroups} -b #{box_id} --cleanup`
+    raise "Cleanup of sandbox #{box_id} failed." if raise_exception && Dir.exists?(workdir)
+  end
+
+  def reset_metadata_file
+    `sudo rm -rf #{metadata_file}`
+    initialize_file(metadata_file)
+  end
+
+  def fix_permissions
+    `sudo chown -R $(whoami): #{boxdir}`
+  end
+
+  def call_callback
+    return unless submission.callback_url.present?
+
+    serialized_submission = ActiveModelSerializers::SerializableResource.new(
+      submission,
+      {
+        serializer: SubmissionSerializer,
+        base64_encoded: true,
+        fields: SubmissionSerializer.default_fields
+      }
+    ).to_json
+
+    Config::CALLBACKS_MAX_TRIES.times do
+      begin
+        response = HTTParty.put(
+          submission.callback_url,
+          body: serialized_submission,
+          headers: {
+            "Content-Type" => "application/json"
+          },
+          timeout: Config::CALLBACKS_TIMEOUT
+        )
+        break
+      rescue Exception => e
+      end
+    end
+  rescue Exception => e
+  end
+
+  def get_metadata
+    metadata = File.read(metadata_file).split("\n").collect do |e|
+      { e.split(":").first.to_sym => e.split(":")[1..-1].join(":") }
+    end.reduce({}, :merge)
+    return metadata
+  end
+
+  def determine_status(status, exit_signal)
+    if status == "TO"
+      return Status.tle
+    elsif status == "SG"
+      return Status.find_runtime_error_by_status_code(exit_signal)
+    elsif status == "RE"
+      return Status.nzec
+    elsif status == "XX"
+      return Status.boxerr
+    elsif submission.expected_output.nil? || strip(submission.expected_output) == strip(submission.stdout)
+      return Status.ac
+    else
+      return Status.wa
+    end
+  end
+
+  def strip(text)
+    return nil unless text
+    text.split("\n").collect(&:rstrip).join("\n").rstrip
+  rescue ArgumentError
+    return text
+  end
+end

app/mailers/application_mailer.rb

@@ -0,0 +1,4 @@
+class ApplicationMailer < ActionMailer::Base
+  default from: '[email protected]'
+  layout 'mailer'
+end

app/models/application_record.rb

@@ -0,0 +1,3 @@
+class ApplicationRecord < ActiveRecord::Base
+  self.abstract_class = true
+end

app/models/language.rb

@@ -0,0 +1,21 @@
+# == Schema Information
+#
+# Table name: languages
+#
+#  id          :integer          not null, primary key
+#  name        :string
+#  compile_cmd :string
+#  run_cmd     :string
+#  source_file :string
+#  is_archived :boolean          default(FALSE)
+#
+
+class Language < ApplicationRecord
+  validates :name, presence: true
+  validates :source_file, :run_cmd, presence: true, unless: -> { is_project }
+  default_scope { where(is_archived: false).order(name: :asc) }
+
+  def is_project
+    name == "Multi-file program"
+  end
+end

app/models/submission.rb

@@ -0,0 +1,261 @@
+# == Schema Information
+#
+# Table name: submissions
+#
+#  id                                         :integer          not null, primary key
+#  source_code                                :text
+#  language_id                                :integer
+#  stdin                                      :text
+#  expected_output                            :text
+#  stdout                                     :text
+#  status_id                                  :integer
+#  created_at                                 :datetime
+#  finished_at                                :datetime
+#  time                                       :decimal(, )
+#  memory                                     :integer
+#  stderr                                     :text
+#  token                                      :string
+#  number_of_runs                             :integer
+#  cpu_time_limit                             :decimal(, )
+#  cpu_extra_time                             :decimal(, )
+#  wall_time_limit                            :decimal(, )
+#  memory_limit                               :integer
+#  stack_limit                                :integer
+#  max_processes_and_or_threads               :integer
+#  enable_per_process_and_thread_time_limit   :boolean
+#  enable_per_process_and_thread_memory_limit :boolean
+#  max_file_size                              :integer
+#  compile_output                             :text
+#  exit_code                                  :integer
+#  exit_signal                                :integer
+#  message                                    :text
+#  wall_time                                  :decimal(, )
+#  compiler_options                           :string
+#  command_line_arguments                     :string
+#  redirect_stderr_to_stdout                  :boolean
+#  callback_url                               :string
+#  additional_files                           :binary
+#  enable_network                             :boolean
+#  started_at                                 :datetime
+#  queued_at                                  :datetime
+#  updated_at                                 :datetime
+#  queue_host                                 :string
+#  execution_host                             :string
+#
+
+class Submission < ApplicationRecord
+  validates :source_code, presence: true, unless: -> { is_project }
+  validates :source_code, absence: true, if: -> { is_project }
+  validates :additional_files, presence: true, if: -> { is_project }
+  validates :language_id, presence: true
+  validates :number_of_runs,
+            numericality: { greater_than: 0, less_than_or_equal_to: Config::MAX_NUMBER_OF_RUNS }
+  validates :cpu_time_limit,
+            numericality: { greater_than_or_equal_to: 0, less_than_or_equal_to: Config::MAX_CPU_TIME_LIMIT }
+  validates :cpu_extra_time,
+            numericality: { greater_than_or_equal_to: 0, less_than_or_equal_to: Config::MAX_CPU_EXTRA_TIME }
+  validates :wall_time_limit,
+            numericality: { greater_than_or_equal_to: 1, less_than_or_equal_to: Config::MAX_WALL_TIME_LIMIT }
+  validates :memory_limit,
+            numericality: { greater_than_or_equal_to: 2048, less_than_or_equal_to: Config::MAX_MEMORY_LIMIT }
+  validates :stack_limit,
+            numericality: { greater_than_or_equal_to: 0, less_than_or_equal_to: Config::MAX_STACK_LIMIT }
+  validates :max_processes_and_or_threads,
+            numericality: { greater_than: 0, less_than_or_equal_to: Config::MAX_MAX_PROCESSES_AND_OR_THREADS }
+  validates :enable_per_process_and_thread_time_limit,
+            inclusion: { in: [false], message: "this option cannot be enabled" },
+            unless: -> { Config::ALLOW_ENABLE_PER_PROCESS_AND_THREAD_TIME_LIMIT }
+  validates :enable_per_process_and_thread_memory_limit,
+            inclusion: { in: [false], message: "this option cannot be enabled" },
+            unless: -> { Config::ALLOW_ENABLE_PER_PROCESS_AND_THREAD_MEMORY_LIMIT }
+  validates :max_file_size,
+            numericality: { greater_than_or_equal_to: 0, less_than_or_equal_to: Config::MAX_MAX_FILE_SIZE }
+  validates :compiler_options, length: { maximum: 512 }
+  validates :command_line_arguments, length: { maximum: 512 }
+  validate :language_existence, :compiler_options_allowed,
+           :command_line_arguments_allowed, :callbacks_allowed,
+           :additional_files_allowed, :network_allowed
+
+  before_create :generate_token
+  before_validation :set_defaults
+
+  enumeration :status
+
+  default_scope { order(created_at: :desc) }
+
+  self.per_page = 20
+
+  def source_code
+    @decoded_source_code ||= Base64Service.decode(self[:source_code])
+  end
+
+  def source_code=(value)
+    super(value)
+    self[:source_code] = Base64Service.encode(self[:source_code])
+  end
+
+
+  def stdin
+    @decoded_stdin ||= Base64Service.decode(self[:stdin])
+  end
+
+  def stdin=(value)
+    super(value)
+    self[:stdin] = Base64Service.encode(self[:stdin])
+  end
+
+
+  def stdout
+    @decoded_stdout ||= Base64Service.decode(self[:stdout])
+  end
+
+  def stdout=(value)
+    super(value)
+    self[:stdout] = Base64Service.encode(self[:stdout])
+  end
+
+
+  def expected_output
+    @decoded_expected_output ||= Base64Service.decode(self[:expected_output])
+  end
+
+  def expected_output=(value)
+    super(value)
+    self[:expected_output] = Base64Service.encode(self[:expected_output])
+  end
+
+
+  def stderr
+    @decoded_stderr ||= Base64Service.decode(self[:stderr])
+  end
+
+  def stderr=(value)
+    super(value)
+    self[:stderr] = Base64Service.encode(self[:stderr])
+  end
+
+
+  def compile_output
+    @decoded_compile_output ||= Base64Service.decode(self[:compile_output])
+  end
+
+  def compile_output=(value)
+    super(value)
+    self[:compile_output] = Base64Service.encode(self[:compile_output])
+  end
+
+
+  def language
+    @language ||= Language.unscoped.find_by(id: language_id)
+  end
+
+
+  def status
+    Status.find_by(id: status_id)
+  end
+
+  def status=(status)
+    self.status_id = status.id
+  end
+
+
+  def is_project
+    language.try(:is_project) || false
+  end
+
+  private
+
+  def language_existence
+    if not language
+      errors.add(:language_id, "language with id #{language_id} doesn't exist")
+    elsif language.is_archived
+      errors.add(:language_id, "language with id #{language_id} is archived and cannot be used anymore")
+    end
+  end
+
+  def compiler_options_allowed
+    return if compiler_options.blank?
+
+    unless Config::ENABLE_COMPILER_OPTIONS
+      errors.add(:compiler_options, "setting compiler options is not allowed")
+      return
+    end
+
+    if language && language.compile_cmd.nil?
+      errors.add(:compiler_options, "setting compiler options is only allowed for compiled languages")
+      return
+    end
+
+    @@allowed_languages ||= Config::ALLOWED_LANGUAGES_FOR_COMPILER_OPTIONS.collect{ |s| s + " " }
+    if language && @@allowed_languages.present? && !language.name.starts_with?(*@@allowed_languages)
+      @@allowed_languages_message ||= @@allowed_languages.size > 1 ? @@allowed_languages[0..-2].collect{ |s| s.strip }.join(", ") + " and " + @@allowed_languages[-1].strip : @@allowed_languages[0].strip
+      errors.add(:compiler_options, "setting compiler options is only allowed for #{@@allowed_languages_message}")
+    end
+  end
+
+  def command_line_arguments_allowed
+    return if command_line_arguments.blank?
+
+    unless Config::ENABLE_COMMAND_LINE_ARGUMENTS
+      errors.add(:command_line_arguments, "setting command line arguments is not allowed")
+    end
+  end
+
+  def callbacks_allowed
+    return if callback_url.blank?
+
+    unless Config::ENABLE_CALLBACKS
+      errors.add(:callback_url, "setting callback is not allowed")
+    end
+  end
+
+  def additional_files_allowed
+    return if additional_files.blank?
+
+    unless Config::ENABLE_ADDITIONAL_FILES
+      errors.add(:additional_files, "setting additional files is not allowed")
+    end
+  end
+
+  def network_allowed
+    return if enable_network.blank?
+
+    unless Config::ALLOW_ENABLE_NETWORK
+      errors.add(:enable_network, "enabling network is not allowed")
+    end
+  end
+
+  def generate_token
+    begin
+      self.token = SecureRandom.uuid
+    end while self.class.exists?(token: token)
+  end
+
+  def set_defaults
+    self.status ||= Status.queue
+    self.number_of_runs ||= Config::NUMBER_OF_RUNS
+    self.cpu_time_limit ||= Config::CPU_TIME_LIMIT
+    self.cpu_extra_time ||= Config::CPU_EXTRA_TIME
+    self.wall_time_limit ||= Config::WALL_TIME_LIMIT
+    self.memory_limit ||= Config::MEMORY_LIMIT
+    self.stack_limit ||= Config::STACK_LIMIT
+    self.max_processes_and_or_threads ||= Config::MAX_PROCESSES_AND_OR_THREADS
+    self.enable_per_process_and_thread_time_limit = NilValue.value_or_default(
+      self.enable_per_process_and_thread_time_limit,
+      Config::ENABLE_PER_PROCESS_AND_THREAD_TIME_LIMIT
+    )
+    self.enable_per_process_and_thread_memory_limit = NilValue.value_or_default(
+      self.enable_per_process_and_thread_memory_limit,
+      Config::ENABLE_PER_PROCESS_AND_THREAD_MEMORY_LIMIT
+    )
+    self.max_file_size ||= Config::MAX_FILE_SIZE
+    self.redirect_stderr_to_stdout = NilValue.value_or_default(
+      self.redirect_stderr_to_stdout,
+      Config::REDIRECT_STDERR_TO_STDOUT
+    )
+    self.enable_network = NilValue.value_or_default(
+      self.enable_network,
+      Config::ENABLE_NETWORK
+    )
+  end
+end

app/serializers/language_serializer.rb

@@ -0,0 +1,3 @@
+class LanguageSerializer < ActiveModel::Serializer
+  attributes :id, :name, :is_archived, :source_file, :compile_cmd, :run_cmd
+end

app/serializers/status_serializer.rb

@@ -0,0 +1,4 @@
+class StatusSerializer < ActiveModel::Serializer
+  attribute(:id) { object.id }
+  attribute(:description) { object.name }
+end

app/serializers/submission_serializer.rb

@@ -0,0 +1,65 @@
+class SubmissionSerializer < ActiveModel::Serializer
+  attributes((Submission.column_names + ["status", "language"] - ["id"]).collect(&:to_sym))
+
+  def self.default_fields
+    @@default_fields ||= [
+      :token,
+      :time,
+      :memory,
+      :stdout,
+      :stderr,
+      :compile_output,
+      :message,
+      :status
+    ]
+  end
+
+  def source_code
+    object_decoder(:source_code)
+  end
+
+  def stdin
+    object_decoder(:stdin)
+  end
+
+  def expected_output
+    object_decoder(:expected_output)
+  end
+
+  def stdout
+    object_decoder(:stdout)
+  end
+
+  def stderr
+    object_decoder(:stderr)
+  end
+
+  def compile_output
+    object_decoder(:compile_output)
+  end
+
+  def message
+    if instance_options[:base64_encoded] and object.message
+      return Base64Service.encode(object.message)
+    end
+    object.message
+  end
+
+  def status
+    { id: object.status_id, description: object.status.name }
+  end
+
+  def language
+    ActiveModelSerializers::SerializableResource.new(object.language, { serializer: LanguageSerializer, fields: [:id, :name] })
+  end
+
+  def additional_files
+    Base64Service.encode(object.additional_files)
+  end
+
+  private
+
+  def object_decoder(method)
+    instance_options[:base64_encoded] ? object[method] : object.send(method)
+  end
+end

app/services/base64_service.rb

@@ -0,0 +1,11 @@
+module Base64Service
+  def self.encode(text)
+    return nil unless text
+    Base64.encode64(text)
+  end
+
+  def self.decode(text)
+    return nil unless text
+    Base64.decode64(text) #.force_encoding("UTF-8").encode
+  end
+end

app/services/fields/submission.rb

@@ -0,0 +1,41 @@
+module Fields
+  class Submission
+    UNIVERSAL_FIELD = :*
+
+    attr_reader :requested_fields, :invalid_fields
+
+    def initialize(fields)
+      @invalid_fields = []
+
+      fields = fields.to_s.split(",").collect(&:to_sym)
+
+      fields.each do |field|
+        if field != UNIVERSAL_FIELD && !available_fields.include?(field)
+          @invalid_fields << field
+        end
+      end
+
+      if fields.include?(UNIVERSAL_FIELD)
+        @requested_fields = available_fields
+      else
+        @requested_fields = (fields - @invalid_fields).presence || default_fields
+      end
+    end
+
+    def has_invalid_fields?
+      !@invalid_fields.empty?
+    end
+
+    def available_fields
+      serializer._attributes
+    end
+
+    def default_fields
+      serializer.default_fields
+    end
+
+    def serializer
+      SubmissionSerializer
+    end
+  end
+end

app/views/layouts/mailer.html.erb

@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
+    <style>
+      /* Email styles need to be inline */
+    </style>
+  </head>
+
+  <body>
+    <%= yield %>
+  </body>
+</html>

app/views/layouts/mailer.text.erb

@@ -0,0 +1 @@
+<%= yield %>

bin/bundle

@@ -0,0 +1,3 @@
+#!/usr/bin/env ruby
+ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../../Gemfile', __FILE__)
+load Gem.bin_path('bundler', 'bundle')

bin/rails

@@ -0,0 +1,9 @@
+#!/usr/bin/env ruby
+begin
+  load File.expand_path('../spring', __FILE__)
+rescue LoadError => e
+  raise unless e.message.include?('spring')
+end
+APP_PATH = File.expand_path('../config/application', __dir__)
+require_relative '../config/boot'
+require 'rails/commands'

bin/rake

@@ -0,0 +1,9 @@
+#!/usr/bin/env ruby
+begin
+  load File.expand_path('../spring', __FILE__)
+rescue LoadError => e
+  raise unless e.message.include?('spring')
+end
+require_relative '../config/boot'
+require 'rake'
+Rake.application.run

bin/setup

@@ -0,0 +1,34 @@
+#!/usr/bin/env ruby
+require 'pathname'
+require 'fileutils'
+include FileUtils
+
+# path to your application root.
+APP_ROOT = Pathname.new File.expand_path('../../', __FILE__)
+
+def system!(*args)
+  system(*args) || abort("\n== Command #{args} failed ==")
+end
+
+chdir APP_ROOT do
+  # This script is a starting point to setup your application.
+  # Add necessary setup steps to this file.
+
+  puts '== Installing dependencies =='
+  system! 'gem install bundler --conservative'
+  system('bundle check') || system!('bundle install')
+
+  # puts "\n== Copying sample files =="
+  # unless File.exist?('config/database.yml')
+  #   cp 'config/database.yml.sample', 'config/database.yml'
+  # end
+
+  puts "\n== Preparing database =="
+  system! 'bin/rails db:setup'
+
+  puts "\n== Removing old logs and tempfiles =="
+  system! 'bin/rails log:clear tmp:clear'
+
+  puts "\n== Restarting application server =="
+  system! 'bin/rails restart'
+end

bin/spring

@@ -0,0 +1,15 @@
+#!/usr/bin/env ruby
+
+# This file loads spring without using Bundler, in order to be fast.
+# It gets overwritten when you run the `spring binstub` command.
+
+unless defined?(Spring)
+  require 'rubygems'
+  require 'bundler'
+
+  if (match = Bundler.default_lockfile.read.match(/^GEM$.*?^    (?:  )*spring \((.*?)\)$.*?^$/m))
+    Gem.paths = { 'GEM_PATH' => [Bundler.bundle_path.to_s, *Gem.path].uniq.join(Gem.path_separator) }
+    gem 'spring', match[1]
+    require 'spring/binstub'
+  end
+end

bin/telemetry

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:35ae04b727c002b3b95ded0fc9f5009e4d8cc64696f5ab7875efebf0a7fd9fbd
+size 2499264

bin/update

@@ -0,0 +1,29 @@
+#!/usr/bin/env ruby
+require 'pathname'
+require 'fileutils'
+include FileUtils
+
+# path to your application root.
+APP_ROOT = Pathname.new File.expand_path('../../', __FILE__)
+
+def system!(*args)
+  system(*args) || abort("\n== Command #{args} failed ==")
+end
+
+chdir APP_ROOT do
+  # This script is a way to update your development environment automatically.
+  # Add necessary update steps to this file.
+
+  puts '== Installing dependencies =='
+  system! 'gem install bundler --conservative'
+  system('bundle check') || system!('bundle install')
+
+  puts "\n== Updating database =="
+  system! 'bin/rails db:migrate'
+
+  puts "\n== Removing old logs and tempfiles =="
+  system! 'bin/rails log:clear tmp:clear'
+
+  puts "\n== Restarting application server =="
+  system! 'bin/rails restart'
+end