Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

add readiness probe #84

Closed
wants to merge 1 commit into from
Closed

add readiness probe #84

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 7 additions & 0 deletions config/default/manager/manager.yaml
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -92,6 +92,13 @@ spec:
- containerPort: 8000
name: webhook-server
protocol: TCP
readinessProbe:
exec:
command:
- cat
- /tmp/ready
initialDelaySeconds: 5
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

why do we need any golang code for this hack? Running cat of an ever-existing file every 5 seconds feels silly.
Would it not be enough to have

   initialDelaySeconds: 20

with a fat comment carrying the same explanation?

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

We need to create the file once the server starts.

I don't think saving 3 cat runs is worth an extra line and comment.

We can replace cat with HTTP GET once controller-runtime implements support for it. I'm not aware of any option that would allow us to stop querying once it succeeds once. https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/#configure-probes

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I was speaking about something like

       readinessProbe:
          exec:
            command:
            - true
          initialDelaySeconds: 20
          periodSeconds: 99999

and dropping the golang changes altogether. But I'm splitting hairs here. The important thing is that you have found the races that @AlonaKaplan has spoken about.

Copy link
Member Author

@phoracek phoracek Jan 10, 2020 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

That would not help. True can succeed as soon as the pod starts. That would be the same as happens with default readiness.

The point here is, that we write the file only once we go through all the initialization and we start the webhook server. In other words, we are marked Ready only once we are able to respond to HTTPS requests for /mutate-virtualmachines.

The extra 20 seconds wait is on top of all the initialization (collecting existing MACs, getting certificates). Those 20 seconds are waiting until the Start hopefully really starts serving.

Copy link
Member Author

@phoracek phoracek Jan 10, 2020 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

We still have races in the test code #83. Unfortunately, the tests are more resilient than the kubemacpool code, so it is all hidden.

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

gotcha.

periodSeconds: 5
terminationGracePeriodSeconds: 5
---
apiVersion: policy/v1beta1
Expand Down
11 changes: 11 additions & 0 deletions pkg/manager/manager.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -149,6 +149,17 @@ func (k *KubeMacPoolManager) Run(rangeStart, rangeEnd net.HardwareAddr) error {
return fmt.Errorf("unable to register webhooks to the manager error %v", err)
}

go func() {
// TODO: We cannot set the probe any closer to the server start.
// Therefore, we add this terrible sleep. It should be replaced by
// proper implementation once https://github.com/kubernetes-sigs/cluster-api/issues/1855
// is finished.
time.Sleep(time.Second * 20)
log.Info("Manager has hopefully started, marking as ready")
os.OpenFile("/tmp/ready", os.O_RDONLY|os.O_CREATE, 0666)
}()

log.Info("Starting manager")
err = mgr.Start(k.restartChannel)
if err != nil {
return fmt.Errorf("unable to run the manager error %v", err)
Expand Down