HOW TO: Heroku Docker Deployment

Heroku Docker Deployment.md

0. Create Something to Deploy
   • Create a Dockerfile in the root directory of the project
     • The Dockerfile location determines the root directory that the docker file's environment is built from
       • I.E. it'll affect ADD, COPY, VOLUME, etc.
     • This should set up the environment for the project to run
     • IF THIS RELIES ON WEB TRAFFIC: a $PORT environment variable is required to be used because Heroku by default doesn't allow port selection. This means you need to rely on the environment having the $PORT variable available when crafting the launch command
       • Example: CMD gunicorn --bind 0.0.0.0:$PORT example.wsgi
   • Try to do all set up in here. A script will only complicate it and make it hard to understand deployment
1. (Optional) Clean up
   • List existing remotes
     • git remote --verbose
   • Delete unecessary remotes
     • git remote rm $REMOTE_NAME
   • List Heroku apps
     • heroku apps
   • Destroy heroku app if needed
     • heroku apps:destroy $HEROKU_APP_NAME --confirm=$HEROKU_APP_NAME
2. Create a heroku.yml in the root of the repository
   • Please see the documentation for how it should look.
   • Pitfall: The dockerfile's location will determine the context for when docker build is called on it
     • Example

       build: 
           docker: 
               example_image: example_api/Dockerfile
       

       • In the above example the root context for the build will be example_api
3. Create Heroku App if it doesn't exist
   • heroku create $HEROKU_APP_NAME --remote $HEROKU_APP_GIT_REMOTE_NAME
     • --remote $HEROKU_APP_GIT_REMOTE_NAME doesn't need to provided, it will default to heroku
     • --remote $HEROKU_APP_GIT_REMOTE_NAME is used because this is a mono repo so different repos will be deploying through different git remote hooks
   • This should only need to be done once in the repo to connect it to heroku
4. Set heroku to use a container stack in order to use Docker/heroku.yml deployments
   • heroku stack:set container
   • What is a Stack?
5. Deploy to Heroku
   • Default deploy
     • git push $HEROKU_APP_GIT_REMOTE_NAME $DESIRED_BRANCH_TO_DEPLOY:master
   • Forcing a deploy in the current branch
     • git push --force $HEROKU_APP_GIT_REMOTE_NAME HEAD:master