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feature-blog(ccm): new metric route_sync_total #54693

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docs(ccm): draft ccm new metric route_sync_total
lukasmetzner Feb 26, 2026
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docs: feature blog content
lukasmetzner Feb 26, 2026
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docs: reference sig-cloud-provider community page
lukasmetzner Feb 26, 2026
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docs: include user stories
lukasmetzner Feb 27, 2026
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docs: update slack link
lukasmetzner Mar 2, 2026
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docs: add example for expected behavior
lukasmetzner Apr 1, 2026
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38 changes: 38 additions & 0 deletions content/en/blog/_posts/2026/ccm-metric-route-sync-total.md
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---
layout: blog
title: "Kubernetes v1.36: New Metric for Route Sync in the Cloud Controller Manager"
date: 2026-02-26
slug: ccm-new-metric-route-sync-total
author: >
[Lukas Metzner](https://github.com/lukasmetzner) (Hetzner)
---

Kubernetes v1.36 introduces a new alpha counter metric `route_controller_route_sync_total`
to the Cloud Controller Manager (CCM) route controller implementation at
[`k8s.io/cloud-provider`](https://github.com/kubernetes/cloud-provider). This metric
increments each time routes are synced with the cloud provider.

## A/B testing watch-based route reconciliation

This metric was added to help operators validate the
`CloudControllerManagerWatchBasedRoutesReconciliation` feature gate introduced in
[Kubernetes v1.35](/blog/2025/12/30/kubernetes-v1-35-watch-based-route-reconciliation-in-ccm/).
That feature gate switches the route controller from a fixed-interval loop to a watch-based
approach that only reconciles when nodes actually change. This reduces unnecessary API calls
to the infrastructure provider, lowering pressure on rate-limited APIs and allowing operators
to make more efficient use of their available quota.

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To A/B test this, compare `route_controller_route_sync_total` with the feature gate
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@michaelasp michaelasp Mar 31, 2026

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Might be good to have an example of what the metric may look like and how to query and poke it in a running cluster? What's the rate of change usually with and without this feature enabled?

This seems like the metric should stay steady, maybe show that when we have the feature disabled it increments steadily and on the other side the metric should stay still until we update the routes.

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@lukasmetzner lukasmetzner Apr 1, 2026

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@michaelasp I have added a small example outlying the expected behavior of the metric with the feature gate enabled and disabled.

As this metric is part of the k8s.io/cloud-provider library, giving a concrete example about how to query this is not feasible here. This depends on the concrete cloud-controller-manager implementation of a cloud-provider.

disabled (default) versus enabled. In clusters where node changes are infrequent, you should
see a significant drop in the sync rate with the feature gate turned on.

## Where can I give feedback?

If you have feedback, feel free to reach out through any of the following channels:
- The [#sig-cloud-provider](https://kubernetes.slack.com/messages/sig-cloud-provider) channel on [Kubernetes Slack](https://slack.k8s.io/)
- The [KEP-5237 issue](https://kep.k8s.io/5237) on GitHub
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- The [SIG Cloud Provider community page](https://github.com/kubernetes/community/tree/05223ecbd2d6f960edb40684dc83d053d49f8b68/sig-cloud-provider) for other communication channels

## How can I learn more?

For more details, refer to [KEP-5237](https://kep.k8s.io/5237).