etcd connecting to wrong cluster

[thdoepke]

I have an existing bare metal kubeadm cluster that I want to migrate to talos. I started with a single node control-plane and now have problems adding other nodes.

The additional nodes don't join the cluster, or at least not all are joining the cluster. I was able to join one node but the other nodes seems to be trying to connect to the existing cluster which is in the same subnet. I already set advertisedSubnets but if I'm correct it affects only the server operation of the etcd node.

192.168.0.53: {"level":"warn","ts":"2025-05-08T14:57:07.417765Z","caller":"embed/config_logging.go:170","msg":"rejected connection on peer endpoint","remote-addr":"192.168.0.100:53034","server-name":"","error":"remote error: tls: bad certificate"}

Is there any solution besides creating a different subnet?

[smira]

It's not quite clear what you are trying to achieve - do you want to scale up kubeadm controlplane with Talos nodes? In that case you want Talos controlplane to join kubeadm controlplane, and PKI should match.

If you want to create a new cluster, just ensure it has unique PKI & other information.

[thdoepke]

Sorry that was a bit misleading. I want to create a new cluster with talos with sperate secrets.

I can see the third node as etcd learner on the other nodes but the services doesn't come up. I first suspected the config but I have a joined node with same config besides ip addresses. But the node also didn't join in the first try.

The etcd log shows the remote-addr 192.168.0.100 which is the ip of a node from the existing cluster. That's why I'm suspecting any kind of problem having both clusters in the same subnet.

[smira]

If that happened, you:

• share PKI with kubeadm cluster - you should use new PKI
• have same controlplane endpoint across kubeadm/Talos clusters

[thdoepke]

The PKI was different but exactly that node was indeed joined with the same IP to the kubeadm cluster in the past and not correctly removed from etcd.

Thanks for pointing me in the right direction.