Understanding authentication and authorization is essential for Kubernetes cluster security and is a core part of the Certified Kubernetes Administrator (CKA) exam. In this blog, we will discuss Kubernetes authentication and authorization.

What Is Kubernetes Authentication?

In Kubernetes, authentication is the process of verifying whether the user has permission to access the Kubernetes with API calls.

Kubernetes does not keep user accounts itself. Instead, it depends on external identity providers and credentials.

Supported Authentication Methods

Common authentication mechanisms include:

  • Client certificates (X.509 certificates signed by the cluster CA)
  • Bearer tokens (bootstrap tokens, service account tokens)
  • OIDC (OpenID Connect) — widely used in production clusters
  • Webhook token authentication
  • Authentication proxies

How Authentication Works

  • A user sends a request to the Kubernetes API server.
  • The API server verifies the request credentials using one or more configured auth modules.
  • If the credentials are valid, the API server identifies the user (username and groups).

Authentication does not decide what the user can do; that is, authorization.

The kubeconfig File

Authentication commonly uses the ~/.kube/config file, which stores:

  • Clusters (API server endpoints and certificate authority)
  • Users (client certificates, keys, tokens, or auth provider configs)
  • Contexts (cluster, user and namespace)

An example config file is given below:

apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSURCVENDQWUyZ0F3SUJBZ0lJQ2hsc0tvL2pkN1V3RFFZSktvWk
    server: https://192.168.201.10:6443
  name: kubernetes
contexts:
- context:
    cluster: kubernetes
    user: kubernetes-admin
  name: kubernetes-admin@kubernetes
current-context: kubernetes-admin@kubernetes
kind: Config
preferences: {}
users:
- name: kubernetes-admin
  user:
    client-certificate-data: LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSURLVENDQWhHZ0F3SUJBZ0lJR2FXWUV3eVhET293RFFZSktvWklodmNOQVFFTEJRQXdGVEVUTU
    client-key-data: LS0tLS1CRUdJTiBSU0EgUFJJVkFURSBLRVktLS0tLQpNSUlFcEFJQkFBS0NBUUVBcjAxSFUxcy9STU1UZzRtSHc4MlREdlBEa29jRWttV

kubeconfig File

What Is Kubernetes Authorization?

In Kubernetes, authorization is the process of verifying the actions that can performed by the user in the clsuter.

Available Authorization Modes

  • RBAC (Role-Based Access Control) — default and recommended
  • Node authorization — for kubelet access
  • Webhook authorization — external policy engines (OPA Gatekeeper, Kyverno)

By default, the user will not have permission to do any action on the cluster the cluster admin has to create a role and cluster role with required permissions and bind it to the user to perform every task.

The user is only authorized to perform the actions specified in the role or cluster role.

RBAC is the most common authorization mechanism in Kubernetes and is heavily tested in the CKA exam. If you want to understand it more clearly, click the link.

CKA Exam Tips

Practice these scenarios:

  • Creating Roles and RoleBindings imperatively command using kubectl create
  • Using the kubectl auth can-i command to verify permissions.
  • Switching contexts using the command kubectl config use-context.
  • Understanding namespace scoped and cluster scoped resources.

Conclusion

In Kubernetes, Authentication and Authorization help you control the level of access granted to a user within the cluster.

I hope this quick guide helps you understand Authentication and Authorization .