Tip: Understand why no user concept in Kubernetes Authentication

 One main authentication mechanism in K8S is:   CA, Certificate, Key

There is no "user"  concept in K8S. Instead, it uses the client private key to identify the "user"

The workflow is like this:

• Users(clients) have their private keys. These keys represent their unique id in K8S.
• Go through the CSR approval process with these keys. We can add CN like user "John" into the CSR process to have a readable "user" id.
• Once CSR is approved, we can get a signed certificate of the private key representing the user "John"
• Then we can authenticate in K8S via  CA, Certificate, Key