c2c393d879
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions here: https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md. Support extra prune resources in kube-addon-manager. The default prune whitelist resources in https://github.com/kubernetes/kubernetes/blob/master/pkg/kubectl/cmd/apply.go#L531 are sometimes not enough. One example is that when we remove an admission webhook running as an addon pod, after we remove the addon yaml file, the admission webhook pod will be pruned, but the `MutatingWebhookConfiguration`/`ValidationWebhookConfiguration` won't... If the webhook failure policy is `Fail`, this will break the cluster, and users can't create new pods anymore. It would be good to at least make this configurable, so that users and vendors can configure it based on their requirement. This PR keeps the default prune resource list exactly the same with before, just makes it possible to add extra ones. @dchen1107 @MrHohn @kubernetes/sig-cluster-lifecycle-pr-reviews @kubernetes/sig-gcp-pr-reviews Signed-off-by: Lantao Liu <lantaol@google.com> **Release note**: ```release-note Support extra `--prune-whitelist` resources in kube-addon-manager. ```
Legacy Cluster add-ons
For more information on add-ons see the documentation.
Overview
Cluster add-ons are resources like Services and Deployments (with pods) that are shipped with the Kubernetes binaries and are considered an inherent part of the Kubernetes clusters.
There are currently two classes of add-ons:
- Add-ons that will be reconciled.
- Add-ons that will be created if they don't exist.
More details could be found in addon-manager/README.md.
Cooperating Horizontal / Vertical Auto-Scaling with "reconcile class addons"
"Reconcile" class addons will be periodically reconciled to the original state given
by the initial config. In order to make Horizontal / Vertical Auto-scaling functional,
the related fields in config should be left unset. More specifically, leave replicas
in ReplicationController / Deployment / ReplicaSet unset for Horizontal Scaling,
leave resources for container unset for Vertical Scaling. The periodic reconcile
won't clobbered these fields, hence they could be managed by Horizontal / Vertical
Auto-scaler.
Add-on naming
The suggested naming for most of the resources is <basename> (with no version number).
Though resources like Pod, ReplicationController and DaemonSet are exceptional.
It would be hard to update Pod because many fields in Pod are immutable. For
ReplicationController and DaemonSet, in-place update may not trigger the underlying
pods to be re-created. You probably need to change their names during update to trigger
a complete deletion and creation.