Kubernetes v1.35: Watch Based Route Reconciliation in the Cloud Controller Manager
Up to and including Kubernetes v1.34, the route controller in Cloud Controller Manager (CCM) implementations built using the k8s.io/cloud-provider library reconciles routes at a fixed interval. This causes unnecessary API requests to the cloud provider when there are no changes to routes. Other controllers implemented through the same library already use watch-based mechanisms, leveraging informers to avoid unnecessary API calls. A new feature gate is being introduced in v1.35 to allow changing the behavior of the route controller to use watch-based informers.
What's new?
The feature gate CloudControllerManagerWatchBasedRoutesReconciliation has been
introduced to k8s.io/cloud-provider in alpha stage by SIG Cloud Provider.
To enable this feature you can use --feature-gate=CloudControllerManagerWatchBasedRoutesReconciliation=true
in the CCM implementation you are using.
About the feature gate
This feature gate will trigger the route reconciliation loop whenever a node is
added, deleted, or the fields .spec.podCIDRs or .status.addresses are updated.
An additional reconcile is performed in a random interval between 12h and 24h, which is chosen at the controller's start time.
This feature gate does not modify the logic within the reconciliation loop. Therefore, users of a CCM implementation should not experience significant changes to their existing route configurations.
How can I learn more?
For more details, refer to the KEP-5237.