Heroku release section overrides release process

Question

I have the following heroku.yml file for containers deployment:

build:
  docker:
    release:
      dockerfile: Dockerfile
      target: release_image
    web: Dockerfile
  config:
    PROD: "True"
release:
  image: web
  command:
    - python manage.py collectstatic --noinput && python manage.py migrate users && python manage.py migrate
run:
  # web: python manage.py runserver 0.0.0.0:$PORT
  web: daphne config.asgi:application --port $PORT --bind 0.0.0.0 -v2
  celery:
    command:
      - celery --app=my_app worker --pool=prefork --concurrency=4 --statedb=celery/worker.state -l info
    image: web
  celery_beat:
    command:
      - celery --app=my_app beat -l info
    image: web

When I deploy I get the following warning, which does not make any sense to me:

Warning: You have declared both a release process type and a release section. Your release process type will be overridden.

My Dockerfile is composed of two stages and I want to keep only the release_image stage:

FROM python:3.8 as builder
...
FROM python:3.8-slim as release_image
...

According to the docs the proper way to choose release_image is to use the target section within build step. But it also mentions that I can run my migrations within a release section.

So what am I supposed to do to get rid of this warning? I could only live with it if it was clear that both my migrations and target are being considered during deploy.Thanks in advance!

Answer 1

I want to keep only the release_image stage

Assuming this is true for your web process as well, update your build section accordingly:

build:
  docker:
    web:
      dockerfile: Dockerfile
      target: release_image
  config:
    PROD: "True"

Now you only have one process type defined and it targets the build stage you want to use.

Since you can run your migrations from the web container there's no need to build a whole container just for your Heroku release process. (And since your release section uses the web image the release process defined in build wouldn't have been for anything used anyway.)