How to create a certificate with Subject Alternative Name (SAN) extensions for OpenShift 4 mirror registry

Issue

• Creating a certificate with Subject Alternative Name (SAN) extensions for RHOCP 4 mirror registry.
• During the upgrade from RHOCP 4.9 to 4.10, the upgrade has stalled and issues are observed with etcd health. The MCP upgrade is stalled and there is one master and one worker node in a Ready,SchedulingDisabled state.

1h57m      Warning  FailedCreatePodSandBox           pod/machine-config-daemon-46bps                 Failed to create pod sandbox: rpc error: code = Unknown desc = error creating pod sandbox with name "k8s_machine-config-daemon-46bps_openshift-machine-config-operator_9f07de57-5b99-4846-a584-eb4740dbf975_0": initializing source docker://quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:fcb3cb6b22fe4946336955472cfbfd0d47034b837f3113cbcf219be77ad64cae: (Mirrors also failed: [registry.cluster.example.com:5000/ocp4/openshift4@sha256:fcb3cb6b22fe4946336955472cfbfd0d47034b837f3113cbcf219be77ad64cae: pinging container registry registry.cluster.example.com:5000: Get "https://registry.cluster.example.com:5000/v2/": x509: certificate relies on legacy Common Name field, use SANs instead]): quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:fcb3cb6b22fe4946336955472cfbfd0d47034b837f3113cbcf219be77ad64cae: pinging container registry quay.io: Get "https://quay.io/v2/": dial tcp: lookup quay.io on 10.0.0.10:53: read udp 10.0.0.20:39303->10.0.0.10:53: i/o timeout

Error can be identified as per following event:

error: unable to push quay.io/openshift-release-dev/ocp-v4.0-art-dev: failed to upload blob sha256:608cfe8580a33a376c92843bd07b2cce574614ac7bff6bddbf03d5f5f44d0b61: Get "https://registry.ocp410.xxx.com:5000/v2/": x509: certificate relies on legacy Common Name field, use SANs instead