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Lab 16.2 Can't join a master node


Hello, I am getting the following error when trying to join the master node. Please advise

sudo kubeadm join k8smaster:6443 --token l9dfr7.m5cv22jb24q96wd4 --discovery-token-ca-cert-hash sha256:1bf5e736621acea1aecbfd10fb2b6a13b5005ccc344f64bb0a10583505be58c5 --control-plane --certificate-key 829e4f757ab4c0144393cdda7a8425bcde430e706deb3856bfe205afd5514a93
[preflight] Running pre-flight checks
[WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/
error execution phase preflight: couldn't validate the identity of the API Server: Get "https://k8smaster:6443/api/v1/namespaces/kube-public/configmaps/cluster-info?timeout=10s": x509: certificate is valid for kubernetes, kubernetes.default, kubernetes.default.svc, kubernetes.default.svc.cluster.local, master, not k8smaster
To see the stack trace of this error execute with --v=5 or higher


  • chrispokorni
    chrispokorni Posts: 2,190

    Hi @pyi1024,

    I have seen similar errors when the cluster was not properly set up in Lab 3, more precisely when the controlPlaneEndpoint did not get proprely set to the k8smaster alias.



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