What is RBAC in Kubernetes?

Short answer

Kubernetes RBAC controls access to cluster resources based on roles. Roles define permissions within a namespace; ClusterRoles define cluster-wide permissions. Bindings assign these roles to users, groups, or service accounts.

How it works

RBAC uses four main objects: Role, ClusterRole, RoleBinding, and ClusterRoleBinding. The API server evaluates RBAC rules on every request. Permissions are additive; there is no deny rule.

Example

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

Bind to a user:

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

Why it matters

RBAC is essential for multi-tenant clusters. It enforces the principle of least privilege and prevents unauthorized access to sensitive resources.

Tips

• Use service accounts for Pod-to-API access.
• Audit RBAC policies regularly.
• Prefer Roles over ClusterRoles where possible.

Common issues

• Wildcard permissions (*) are dangerous.
• RoleBindings only work within a namespace.
• Changes to RBAC take effect immediately without restart.