Invalid x509 certificate for kubernetes master
I am trying reach my k8s master from my workstation. I can access the master from the LAN fine but not from my workstation. The error message is:
% kubectl --context=employee-context get pods
Unable to connect to the server: x509: certificate is valid for 10.96.0.1, 10.161.233.80, not 114.215.201.87
How can I do to add 114.215.201.87 to the certificate? Do I need to remove my old cluster ca.crt, recreate it, restart whole cluster and then resign client certificate? I have deployed my cluster with kubeadm and I am not sure how to do these steps manually.
Answer
One option is to tell kubectl that you don't want the certificate to be validated. Obviously this brings up security issues but I guess you are only testing so here you go:
kubectl --insecure-skip-tls-verify --context=employee-context get pods
The better option is to fix the certificate. Easiest if you reinitialize the cluster by running kubeadm reset on all nodes including the master and then do
kubeadm init --apiserver-cert-extra-sans=114.215.201.87
It's also possible to fix that certificate without wiping everything, but that's a bit more tricky. Execute something like this on the master as root:
rm /etc/kubernetes/pki/apiserver.*
kubeadm alpha phase certs selfsign --apiserver-advertise-address=0.0.0.0 --cert-altnames=10.161.233.80 --cert-altnames=114.215.201.87
docker rm `docker ps -q -f 'name=k8s_kube-apiserver*'`
systemctl restart kubelet