Information
Allow pods to verify the API server's serving certificate before establishing connections.
Rationale:
Processes running within pods that need to contact the API server must verify the API server's serving certificate. Failing to do so could be a subject to man-in-the-middle attacks. Providing the root certificate for the API server's serving certificate to the controller manager with the `--root-ca-file` argument allows the controller manager to inject the trusted bundle into pods so that they can verify TLS connections to the API server.
Solution
Edit the `/etc/kubernetes/controller-manager` file on the master node and set the `KUBE_CONTROLLER_MANAGER_ARGS` parameter to include `--root-ca-file=`: `KUBE_CONTROLLER_MANAGER_ARGS='--root-ca-file='`
Based on your system, restart the `kube-controller-manager` service. For example: `systemctl restart kube-controller-manager.service`
Impact:
You need to setup and maintain root certificate authority file.