ssl - kubectl unable to connect to server: x509: certificate signed by unknown authority

Question

i'm getting an error when running kubectl one one machine (windows)

the k8s cluster is running on CentOs 7 kubernetes cluster 1.7 master, worker

Here's my .kubeconfig

  
apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: REDACTED
    server: https://10.10.12.7:6443
  name: kubernetes
contexts:
- context:
    cluster: kubernetes
    user: system:node:localhost.localdomain
  name: system:node:localhost.localdomain@kubernetes
current-context: system:node:localhost.localdomain@kubernetes
kind: Config
preferences: {}
users:
- name: system:node:localhost.localdomain
  user:
    client-certificate-data: REDACTED
    client-key-data: REDACTED
  

the cluster is built using kubeadm with the default certificates on the pki directory

kubectl unable to connect to server: x509: certificate signed by unknown authority

Answer 1

One more solution in case it helps anyone:

My scenario:

• using Windows 10
• Kubernetes installed via Docker Desktop ui 2.1.0.1
• the installer created config file at ~/.kube/config
• the value in ~/.kube/config for server is https://kubernetes.docker.internal:6443
• using proxy

Issue: kubectl commands to this endpoint were going through the proxy, I figured it out after running kubectl --insecure-skip-tls-verify cluster-info dump which displayed the proxy html error page.

Fix: just making sure that this URL doesn't go through the proxy, in my case in bash I used export no_proxy=$no_proxy,*.docker.internal