This eliminates the race condition that results in the runner terminated prematurely when RunnerSet triggered unregistration of StatefulSet that added just a few seconds ago.
I can't find any requests made by user agent `actions-runner-controller` in GitHub.com's telemetry in the past 7 days.
Turns out we only set user agent `actions-runner-controller` if we are configured to use BasicAuth which is not the case for most customers I think.
I update the code a little bit to make sure it always set `actions-runner-controller` as UserAgent for the GitHub HttpClient in ARC.
A further step would be somehow baking the ARC release version into the UserAgent as well.
Enhances ARC(both the controller-manager and github-webhook-server) to cache any GitHub API responses with HTTP GET and an appropriate Cache-Control header.
Ref #920
## Cache Implementation
`gregjones/httpcache` has been chosen as a library to implement this feature, as it is as recommended in `go-github`'s documentation:
https://github.com/google/go-github#conditional-requests
`gregjones/httpcache` supports a number of cache backends like `diskcache`, `s3cache`, and so on:
https://github.com/gregjones/httpcache#cache-backends
We stick to the built-in in-memory cache as a starter. Probably this will never becomes an issue as long as various HTTP responses for all the GitHub API calls that ARC makes, list-runners, list-workflow-jobs, list-runner-groups, etc., doesn't overflow the in-memory cache.
`httpcache` has an known unfixed issue that it doesn't update cache on chunked responses. But we assume that the APIs that we call doesn't use chunked responses. See #1503 for more information on that.
## Ephemeral runner pods are no longer recreated
The addition of the cache layer resulted in a slow down of a scale-down process and a trade-off between making the runner pod termination process fragile to various race conditions(shorter grace period before runner deletion) or delaying runner pod deletion depending on how long the grace period is(longer grace period). A grace period needs to be at least longer than 60s (which is the same as cache duration of ListRunners API) to not prematurely delete a runner pod that was just created.
But once I disabled automatic recreation of ephemeral runner pod, it turned out to be no more of an issue when it's being scaled via workflow_job webhook.
Ephemeral runner resources are still automatically added on demand by RunnerDeployment via RunnerReplicaSet(I've added `EffectiveTime` fields to our CRDs but that's an implementation detail so let's omit). A good side-effect of disabling ephemeral runner pod recreations is that ARC will no longer create redundant ephemeral runners when used with webhook-based autoscaler.
Basically, autoscaling still works as everyone might expect. It's just better than before overall.
Enhances runner controller and runner pod controller to have consistent timeouts for runner unregistration and runner pod deletion,
so that we are very much unlikely to terminate pods that are running any jobs.
so that you can run `kubectl logs` on controller pods without the specifying the container name.
It is especially useful when you want to run kubectl-logs on all ARC pods across controller-manager and github-webhook-server like:
```
kubectl -n actions-runner-system logs -l app.kubernetes.io/name=actions-runner-controller
```
That was previously impossible due to that the selector matches pods from both controller-manager and github-webhook-server and kubectl does not provide a way to specify container names for respective pods.
Yusuke Kuoka
Renovate Bot
renovate[bot]
Felipe Galindo Sanchez
Daniel
Callum Tait
Tingluo Huang
Javier Sotelo