feat(docker): Depends_on based on initializer

[kiblik]

This change blocks the start of uwsgi, celerybeat, and celeryworker until initializer is not completed_successfully. This is useful for:

• avoiding errors in uwsgi, celerybeat, and celeryworker during start-up when the db is not ready
• make it easier to identify errors with initializer (they might get easily lost within other logs).

[dryrunsecurity]

No security concerns detected in this pull request.

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All finding details can be found in the DryRun Security Dashboard.

[valentijnscholten]

Cool! What happens when there is an error in the initializer? I guess it just fails with an error and the other containers are never started?

[kiblik]

Cool! What happens when there is an error in the initializer? I guess it just fails with an error and the other containers are never started?

Exactly (well, except psql and redis - they do not use dependency, so they would still be running)

For testing, I changed models.py, did not prepare migrations, initializer failed, and the whole process of startup stopped (docker did not touch uwsgi, nginx or celery*). This was the last message before coming back to bash.

service "initializer" didn't complete successfully: exit 1