Kubernetes v1.35: Watch Based Route Reconciliation in the Cloud Controller Manager
Kubernetes Blog
December 30, 2025
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.
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Originally published on Kubernetes Blog on 12/30/2025