app.py

import subprocess

subprocess.run("echo 'node version:' && node --version", shell=True)
subprocess.run("echo 'npm version:' && npm --version", shell=True)
subprocess.run("pwd && ls -al", shell=True)
subprocess.run("export PORT=7860", shell=True)
subprocess.run(["echo", '"PORT set to $PORT"'])

subprocess.run("npm run install --prefix app", shell=True)
subprocess.run("npm run build --prefix app", shell=True)
subprocess.run("node app/build", shell=True)