You can verify the expiration date of kubeconfig in the current context as follows:
kubectl config view --minify --raw --output 'jsonpath={..user.client-certificate-data}' | base64 -d | openssl x509 -noout -enddate
❯ k config current-context
sc2-01-vcxx
❯
❯ kubectl config view --minify --raw --output 'jsonpath={..user.client-certificate-data}' | base64 -d | openssl x509 -noout -enddate
notAfter=Sep 6 05:13:47 2023 GMT
❯
❯ date
Thu Sep 7 18:05:52 IST 2023
❯
Note that the supervisor control plane component certificates will expire after one year.
Here is the VMware KB: https://kb.vmware.com/s/article/89324
NOTE: If certificates expire on the Supervisor or Guest Clusters, access and management of the clusters will fail. And, you will need to raise a case with VMware support team for assistance.
Keep a note of this cert expiry date, and if you can update the supervisor cluster atleast once in a year, these certs will get updated.
Here is a quick way to check the expiry of the supervisor control plane certs.
❯ k config current-context
sc2-06-d5165f-vc01
❯
❯ k cluster-info
Kubernetes control plane is running at https://10.43.69.117:6443
KubeDNS is running at https://10.43.69.117:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
❯
❯ echo | openssl s_client -servername 10.43.69.117 -connect 10.43.69.117:6443 | openssl x509 -noout -dates
depth=0 CN = kube-apiserver
verify error:num=20:unable to get local issuer certificate
verify return:1
depth=0 CN = kube-apiserver
verify error:num=21:unable to verify the first certificate
verify return:1
DONE
notBefore=Jun 2 09:36:17 2023 GMT
notAfter=Jun 1 09:36:18 2024 GMT
❯
Thanks to my friend Ravikrithik Udainath for the above openssl tip!
I am using the admin kubeconfig of the supervisor cluster. Here is the link to my previous article on exporting WCP admin kubeconfig file. In this case, 10.43.69.117 is the floating IP for the supervisor control plane and it is assigned to one of the supervisor control plane VMs.
This vSphere with Tanzu cluster was deployed on June 02, 2023, and as you can see above, the certificate expiry will be after one year, which in this case is June 01, 2024.
You can set up some sort of monitoring/ alerting for all your supervisor clusters to get notification on these expiry dates.
Hope it was useful. Cheers!
