In GCP, once an external IP address is assigned to master/infra node through GCP console, numbers of pending CSR from kubernetes.io/kubelet-serving is increasing, and the following error are reported:

I0902 10:48:29.254427       1 controller.go:121] Reconciling CSR: csr-q7bwd
I0902 10:48:29.365774       1 csr_check.go:157] csr-q7bwd: CSR does not appear to be client csr
I0902 10:48:29.371827       1 csr_check.go:545] retrieving serving cert from build04-c92hb-master-1.c.openshift-ci-build-farm.internal (10.0.0.5:10250)
I0902 10:48:29.375052       1 csr_check.go:188] Found existing serving cert for build04-c92hb-master-1.c.openshift-ci-build-farm.internal
I0902 10:48:29.375152       1 csr_check.go:192] Could not use current serving cert for renewal: CSR Subject Alternate Name values do not match current certificate
I0902 10:48:29.375166       1 csr_check.go:193] Current SAN Values: [build04-c92hb-master-1.c.openshift-ci-build-farm.internal 10.0.0.5], CSR SAN Values: [build04-c92hb-master-1.c.openshift-ci-build-farm.internal 10.0.0.5 35.211.234.95]
I0902 10:48:29.375175       1 csr_check.go:202] Falling back to machine-api authorization for build04-c92hb-master-1.c.openshift-ci-build-farm.internal
E0902 10:48:29.375184       1 csr_check.go:420] csr-q7bwd: IP address '35.211.234.95' not in machine addresses: 10.0.0.5
I0902 10:48:29.375193       1 csr_check.go:205] Could not use Machine for serving cert authorization: IP address '35.211.234.95' not in machine addresses: 10.0.0.5
I0902 10:48:29.379457       1 csr_check.go:218] Falling back to serving cert renewal with Egress IP checks
I0902 10:48:29.382668       1 csr_check.go:221] Could not use current serving cert and egress IPs for renewal: CSR Subject Alternate Names includes unknown IP addresses
I0902 10:48:29.382702       1 controller.go:233] csr-q7bwd: CSR not authorized

4.11.2

1. Assign external IPs to master/infra node in GCP
2. oc get csr | grep kubernetes.io/kubelet-serving

CSRs are not approved

CSRs are approved

This issue is only happen in GCP. Same OpenShift installations in AWS do not have this issue.

It looks like the CSR are created using external IP addresses once assigned.

Ref: https://coreos.slack.com/archives/C03KEQZC1L2/p1662122007083059