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@mumoshu mumoshu commented Mar 6, 2022

While testing #1179, I discovered that ARC sometimes stop resyncing RunnerReplicaSet when the desired replicas is greater than the actual number of runner pods.
This seems to happen when ARC missed receiving a workflow_job completion event but it has no way to decide if it is either (1) something went wrong on ARC or (2) a loadbalancer in the middle or GitHub or anything not ARC went wrong. It needs a standard to decide it, or if it's not impossible, how to deal with it.

In this change, I added a hard-coded 10 minutes timeout(can be made customizable later) to prevent runner pod recreation.
Now, a RunnerReplicaSet/RunnerSet to restart runner pod recreation 10 minutes after the last scale-up. If the workflow completion event arrived after the timeout, it will decrease the desired replicas number that results in the removal of a runner pod. The removed runner pod might be deleted without ever being used, but I think that's better than leaving the desired replicas and the actual number of replicas diverged forever.

@mumoshu mumoshu changed the title Auto-correct desired replicas on missing webhook_job completion event Auto-correct replicas number on missing webhook_job completion event Mar 6, 2022
While testing #1179, I discovered that ARC sometimes stop resyncing RunnerReplicaSet when the desired replicas is greater than the actual number of runner pods.
This seems to happen when ARC missed receiving a workflow_job completion event but it has no way to decide if it is either (1) something went wrong on ARC or (2) a loadbalancer in the middle or GitHub or anything not ARC went wrong. It needs a standard to decide it, or if it's not impossible, how to deal with it.

In this change, I added a hard-coded 10 minutes timeout(can be made customizable later) to prevent runner pod recreation.
Now, a RunnerReplicaSet/RunnerSet to restart runner pod recreation 10 minutes after the last scale-up. If the workflow completion event arrived after the timeout, it will decrease the desired replicas number that results in the removal of a runner pod. The removed runner pod might be deleted without ever being used, but I think that's better than leaving the desired replicas and the actual number of replicas diverged forever.
@mumoshu mumoshu force-pushed the auto-correct-replicas-on-missing-workflow-job-completion-event branch from 7107949 to cb1029c Compare March 6, 2022 23:37
@mumoshu mumoshu merged commit cbbc383 into master Mar 7, 2022
@mumoshu mumoshu deleted the auto-correct-replicas-on-missing-workflow-job-completion-event branch March 7, 2022 00:35
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2 participants