Kubernetes v1.36 Introduces New Metric for Route Sync in Cloud Controller Manager

Introduction of New Metric

Kubernetes v1.36 has introduced an alpha metric named route_controller_route_sync_total. This metric is associated with the Cloud Controller Manager's route controller implementation, and it increments every time routes are synced with the cloud provider.

Purpose of the New Metric

The new metric aims to assist operators in validating the CloudControllerManagerWatchBasedRoutesReconciliation feature gate from Kubernetes v1.35. This feature switched the route controller from using a fixed-interval loop to a watch-based system, triggering reconciliations only when actual node changes occur.

Impact on API Calls

By utilizing the watch-based approach, Kubernetes reduces the number of unnecessary API calls made to infrastructure providers, which is particularly beneficial in reducing pressure on rate-limited APIs. This allows operators to optimize their available quota more effectively.

Testing the New Feature

Operators can compare the route_controller_route_sync_total metric's behavior with the feature gate disabled versus enabled. In clusters with infrequent node changes, significant reductions in the sync rate should be observable with the feature gate activated, contrasting with the steady increment seen when it is disabled.

Conclusion and Communication Channels

Feedback on this implementation can be directed through various channels, including the Kubernetes Slack and GitHub. For more details regarding the feature, reference KEP-5237.