Update Dockerfile

Dockerfile

@@ -21,6 +21,9 @@ RUN apt-get update && apt-get install -y wget unzip
 RUN wget https://bin.equinox.io/c/4VmDzA7iaHb/ngrok-stable-linux-amd64.zip
 RUN unzip ngrok-stable-linux-amd64.zip -d /home/ngrok
 
+# Set ngrok authtoken
+RUN /home/ngrok/ngrok authtoken NGROK_AUTHTOKEN
+
 WORKDIR /app
 
 # Create a non-privileged user that the app will run under.