Configure task behavior to acknowledge after execution to trigger requeuing when interrupted

[bjester]

Summary

Description of the change(s) you made

• Adds celery task options that will cause interrupted tasks to be requeued
• Adds celery app method for querying what's in the queue
• Removes flags added in Disable mingle and gossip when running workers. #1519

Manual verification steps performed

1. Step 1
2. Step 2
3. ...

Logging snapshots

When a worker is forcibly interrupted, it should restore (unacknowledged) tasks to the queue:

[2021-09-23 16:22:57,214: INFO/MainProcess] Connected to redis://localhost:6379/0
[2021-09-23 16:22:57,223: INFO/MainProcess] celery@phlack ready.
[2021-09-23 16:22:57,233: INFO/MainProcess] Received task: calculate_user_storage_task[69d10852-22ea-48a0-809d-d97ade8a2218]  ETA:[2021-09-23 14:32:37.734031-07:53] 
[2021-09-23 16:23:16,978: INFO/MainProcess] Received task: export_channel_task[1789ac915aca4519bf04a8c7755f5efc]  
^C
worker: Hitting Ctrl+C again will terminate all running tasks!

worker: Warm shutdown (MainProcess)
^C
worker: Cold shutdown (MainProcess)
[2021-09-23 17:12:01,685: WARNING/MainProcess] Restoring 2 unacknowledged message(s)

Does this introduce any tech-debt items?

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Reviewer guidance

How can a reviewer test these changes?

1. Add a time.sleep(10000) to a task such as the publish task
2. Initiate publishing of a channel
3. Start the celery workers
4. Observe the workers should start the task
5. Send signal to terminate workers twice: Ctrl+C
6. Observe during worker shutdown you should see a message like Restoring 1 unacknowledged message(s); other incomplete scheduled tasks should be included such as tasks with an ETA
7. Start the celery workers again
8. Observe celery should restart the publishing task

Are there any risky areas that deserve extra testing?

References

https://docs.celeryproject.org/en/v4.4.7/userguide/configuration.html#std:setting-task_acks_late
https://docs.celeryproject.org/en/v4.4.7/faq.html#faq-acks-late-vs-retry
Querying celery queue directly: redis-cli LRANGE celery 0 -1

Comments

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Contributor's Checklist

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Reviewer's Checklist

This section is for reviewers to fill out.

• Automated test coverage is satisfactory
• PR is fully functional
• PR has been tested for accessibility regressions
• External dependency files were updated if necessary (yarn and pip)
• Documentation is updated
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[sonarqubecloud]

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