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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.

Janos Lenart
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user1208081
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9 Answers9

76

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 init phase certs all --apiserver-advertise-address=0.0.0.0 --apiserver-cert-extra-sans=10.161.233.80,114.215.201.87
docker rm `docker ps -q -f 'name=k8s_kube-apiserver*'`
systemctl restart kubelet
Janos Lenart
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    I think this is not a legit answer anymore because this `alpha` subcommand is not available [anymore](https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm-alpha/#cmd-certs-renew). – Ivan Aracki Jan 26 '19 at 13:31
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    For kubeadm 1.15, just run command `kubeadm alpha certs renew all` – fkpwolf Jul 19 '19 at 03:06
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    because kubeadm `alpha` subcommand is not available anymore, you can replace it with the following command `kubeadm init phase certs all --apiserver-advertise-address=0.0.0.0 --apiserver-cert-extra-sans=10.161.233.80,114.215.201.87` – Prasta Maha Jul 22 '21 at 08:08
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This command for new kubernetes >=1.8:

rm /etc/kubernetes/pki/apiserver.*
kubeadm alpha phase certs all --apiserver-advertise-address=0.0.0.0 --apiserver-cert-extra-sans=10.161.233.80,114.215.201.87
docker rm -f `docker ps -q -f 'name=k8s_kube-apiserver*'`
systemctl restart kubelet

Also whould be better to add dns name into --apiserver-cert-extra-sans for avoid issues like this in next time.

kvaps
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19

For kubeadm v1.13.3

rm /etc/kubernetes/pki/apiserver.*
kubeadm init phase certs all --apiserver-advertise-address=0.0.0.0 --apiserver-cert-extra-sans=114.215.201.87
docker rm -f `docker ps -q -f 'name=k8s_kube-apiserver*'`
systemctl restart kubelet
Marcin Król
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  • works also nicely with v1.14.3. One thing I might add: Looks like private IPs are automatically added to `--apiserver-cert-extra-sans`, so you'll only have to add additional public IPs there – Marcus Schiesser Jun 21 '19 at 09:23
  • Works also nicely with v1.17.2. I needed --apiserver-cert-extra-sans=aaa,bbb,ccc,ddd,eee. – qräbnö Feb 09 '20 at 22:37
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If you used kubespray to provision your cluster then you need to add a 'floating ip' (in your case its '114.215.201.87'). This variable is called supplementary_addresses_in_ssl_keys in the group_vars/k8s-cluster/k8s-cluster.yml file. After updating it, just re-run your ansible-playbook -b -v -i inventory/<WHATEVER-YOU-NAMED-IT>/hosts.ini cluster.yml.

NOTE: you still have to remove all the apiserver certs (rm /etc/kubernetes/pki/apiserver.*) from each of your master nodes prior to running!

Marc
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Issue cause: Your configs at $HOME/.kube/ are present with your old IP address.

Try running,

rm $HOME/.kube/* -rf
cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
chown $(id -u):$(id -g) $HOME/.kube/config
Sarath kumar S
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    This has nothing to do about .kube directory. It's possible that the IP does not match, but it doesn't mean we need to delete it. – Ahmed Jan 26 '19 at 07:16
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For Kubernetes 1.12.2/CentOS 7.4 the sequence is as follows:

rm /etc/kubernetes/pki/apiserver.*
kubeadm alpha phase certs all --apiserver-advertise-address=0.0.0.0 --apiserver-cert-extra-sans=51.158.75.136
docker rm -f `docker ps -q -f 'name=k8s_kube-apiserver*'`
systemctl restart kubelet
zjor
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Use the following command: 

kubeadm init phase certs all
Shahbaz A.
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KlSoft
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0

For me when I was trying to accessing via root (after sudo -i) I got the error. I excited and with normal user it was working.

Vipul Pandey
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-1

For me the following helped:

  1. rm -rf ~/.minikube
  2. minikube delete
  3. minikube start

Probably items no 2 and 3 would have been sufficient