OCPBUGS-95087: reload client CA after kubelet-ca.crt is replaced

[arpitbhagat]

What type of PR is this?

/kind bug

What this PR does / why we need it:

OpenShift scrapes CRI-O metrics through the kube-rbac-proxy-crio static pod on :9637 (job=crio). That process authenticates Prometheus with --client-ca-file=/etc/kubernetes/kubelet-ca.crt. Machine Config Operator writes that file atomically whenever the cluster client CA is updated.

Today kube-rbac-proxy loads the CA at start (and on filesystem events for the original inode) and then keeps it in memory. After MCO replaces the file, TLS to :9637 still succeeds, but client-certificate authentication returns HTTP 401 (x509: certificate signed by unknown authority). Cluster Monitoring then fires TargetDown for job=crio. Restarting the static pod reloads the CA from disk and clears the alert until the next CA rewrite.

This change reloads the client CA on a one-minute timer as well as on filesystem events, so an MCO rewrite is picked up without restarting the proxy. The same reload is applied to the serving cert/key watcher so those files cannot stick on a stale inode either.

Which issue(s) this PR is related to:

Related: OCPBUGS-95087

Special notes for your reviewer:

• Reload interval stays 1 minute.
• Authentication and authorization wiring is unchanged (--client-ca-file, static auth for prometheus-k8s).

Does this PR introduce a user-facing change?

kube-rbac-proxy now reloads the client CA file on a timer, so replacing kubelet-ca.crt no longer leaves CRI-O metrics scrapes failing with HTTP 401.

[openshift-merge-bot]

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[openshift-ci-robot]

@arpitbhagat: This pull request references Jira Issue OCPBUGS-95087, which is invalid:

• release note text must be set and not match the template OR release note type must be set to "Release Note Not Required". For more information you can reference the OpenShift Bug Process.
• expected Jira Issue OCPBUGS-95087 to depend on a bug targeting a version in 4.20.0, 4.20.z and in one of the following states: VERIFIED, RELEASE PENDING, CLOSED (ERRATA), CLOSED (CURRENT RELEASE), CLOSED (DONE), CLOSED (DONE-ERRATA), but no dependents were found

Comment /jira refresh to re-evaluate validity if changes to the Jira bug are made, or edit the title of this pull request to link to a different bug.

The bug has been updated to refer to the pull request using the external bug tracker.

Details

In response to this:

What type of PR is this?

/kind bug

What this PR does / why we need it:

OpenShift scrapes CRI-O metrics through the kube-rbac-proxy-crio static pod on :9637 (job=crio). That process authenticates Prometheus with --client-ca-file=/etc/kubernetes/kubelet-ca.crt. Machine Config Operator writes that file atomically whenever the cluster client CA is updated.

Today kube-rbac-proxy loads the CA at start (and on filesystem events for the original inode) and then keeps it in memory. After MCO replaces the file, TLS to :9637 still succeeds, but client-certificate authentication returns HTTP 401 (x509: certificate signed by unknown authority). Cluster Monitoring then fires TargetDown for job=crio. Restarting the static pod reloads the CA from disk and clears the alert until the next CA rewrite.

This change reloads the client CA on a one-minute timer as well as on filesystem events, so an MCO rewrite is picked up without restarting the proxy. The same reload is applied to the serving cert/key watcher so those files cannot stick on a stale inode either.

Which issue(s) this PR is related to:

Related: OCPBUGS-95087

Special notes for your reviewer:

• Reload interval stays 1 minute.
• Authentication and authorization wiring is unchanged (--client-ca-file, static auth for prometheus-k8s).

Does this PR introduce a user-facing change?

kube-rbac-proxy now reloads the client CA file on a timer, so replacing kubelet-ca.crt no longer leaves CRI-O metrics scrapes failing with HTTP 401.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the openshift-eng/jira-lifecycle-plugin repository.

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[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: arpitbhagat
Once this PR has been reviewed and has the lgtm label, please assign ibihim for approval. For more information see the Code Review Process.

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Details

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[openshift-ci]

Hi @arpitbhagat. Thanks for your PR.

I'm waiting for a openshift member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work.

Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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Details

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.