We will run a separate pod for the beat worker. There should only ever
be a single beat worker (to avoid redundant work) so the number of
replicas needs to be managed independently.
This adds both the Kubernetes config for the new pod and additional
CircleCI config to swap a new image into the pod during CD.
This will allow Kubernetes resources that only pull images occasionally
(i.e., k8s jobs) to point to a static tag name, "latest", that is updated
regularly. It also means we can refer to that image in the k8s config
tracked in the repo, instead of out-of-date images.
Celery provides a more robust set of queueing options for both tasks and
worker processes. Updates include:
- infrastructure necessary to run Celery, including celery entrypoint
- backgrounded functions are now imported directly from atst.jobs
- update tests as-needed
- update kubernetes worker pod command
