898831ad9d
Automatic merge from submit-queue (batch tested with PRs 63453, 64592, 64482, 64618, 64661). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>. Revert "Remove rescheduler and corresponding tests from master" Reverts kubernetes/kubernetes#64364 After discussing with @bsalamat on how DS controllers(ref: https://github.com/kubernetes/kubernetes/pull/63223#discussion_r192277527) cannot create pods if the cluster is at capacity and they have to rely on rescheduler for making some space, we thought it is better to - Bring rescheduler back. - Make rescheduler priority aware. - If cluster is full and if **only** DS controller is not able to create pods, let rescheduler be run and let it evict some pods which have less priority. - The DS controller pods will be scheduled now. So, I am reverting this PR now. Step 2, 3 above are going to be in rescheduler. /cc @bsalamat @aveshagarwal @k82cn Please let me know your thoughts on this. ```release-note Revert #64364 to resurrect rescheduler. More info https://github.com/kubernetes/kubernetes/issues/64725 :) ```
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.