RBAC

Core Concepts

RBAC controls who can do what in your Kubernetes cluster. It sets permissions for accessing the Kubernetes API and is essential for securing clusters with multiple users or teams. Kubernetes RBAC grants specific actions (verbs) on resources to users or service accounts.

RBAC Objects

Kind Purpose
Role Grants permissions within a single namespace
ClusterRole Grants permissions cluster-wide
RoleBinding Assigns a Role to a user/group in a namespace
ClusterRoleBinding Assigns a ClusterRole to a user/group across all namespaces

Example: Read-Only Role in a Namespace

apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: pod-reader
  namespace: dev
rules:
  - apiGroups: [""]
    resources: ["pods"]
    verbs: ["get", "list"]

Binding the Role

apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: read-pods
  namespace: dev
subjects:
  - kind: User
    name: alice
roleRef:
  kind: Role
  name: pod-reader
  apiGroup: rbac.authorization.k8s.io

This lets alice read pods in the dev namespace only.

Cluster-Wide Example

To give a user full access to nodes and persistent volumes across the cluster:

kind: ClusterRole
rules:
  - apiGroups: [""]
    resources: ["nodes", "persistentvolumes"]
    verbs: ["get", "list", "watch"]

Bind it using a ClusterRoleBinding to apply cluster-wide.

Common Verbs

  • get, list, watch: Read operations
  • create, update, patch, delete: Write operations
  • impersonate: Required to act as another user/service account

Common RBAC Pitfalls

  • Forgetting to bind a Role: RBAC rules do nothing unless bound
  • Using ClusterRole when Role is safer
  • Not scoping permissions - always follow least privilege

Audit & RBAC

Pair RBAC with audit logging to:

  • Detect excessive privileges
  • Track unauthorized access attempts
  • Ensure least privilege policies are followed

Summary

  • RBAC defines access to Kubernetes API resources
  • Use Role/RoleBinding for namespaced access, ClusterRole for global access
  • Grant least privilege and bind only what’s necessary
  • Essential for securing clusters and enabling multi-team usage