Known errors and solutions

Problems and solutions

Unable to connect to the server: x509: certificate signed by unknown authority (possibly because of "crypto/rsa: verification error" while trying to verify candidate authority certificate "kubernetes")

This error happened after a "kubeadm reset" and "init". Any kubectl command returned this error because the /root/.kube/config was still using the old certificate.

To fix it, just copy the new config:

cp /etc/kubernetes/admin.conf /root/.kube/config

Error execution phase kubelet-start: configmaps "kubelet-config-1.14" is forbidden: User "system:bootstrap:g651e8" cannot get resource "configmaps" in API group "" in the namespace "kube-system"

This error happens when trying to join a node and the it mismatches master's kubelet, kubeadm and kubectl version.

To fix it, install on the worker node the same master's versions.

To check master versions run:

kubelet --version
kubeadm version
kubectl version
dpkg --list |grep kubernetes-cni

Make sure your worker node has the same versions available:

apt-cache policy kubelet
apt-cache policy kubeadm
apt-cache policy kubectl
apt-cache policy kubernetes-cni

Install on the worker node the same versions, for example:

apt-get install \
  kubelet=1.13.4-00 \
  kubeadm=1.13.4-00 \
  kubectl=1.13.4-00 \
  kubernetes-cni=0.6.0-00