Ensure that the --root-ca-file argument is set as appropriate

Description:

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.

You need to setup and maintain root certificate authority file.

Edit the Controller Manager pod specification file '/etc/kubernetes/manifests/kube-controller-manager.yaml' on the master node and set the '--root-ca-file' parameter to the certificate bundle file'.

--root-ca-file=<path/to/file>
.