Understanding Kubernetes: Part 28 ClusterRole and ClusterRoleBinding

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📢 If you’ve been following our Kubernetes series 2025, welcome back! For new readers, check out Part 27: Role and RoleBinding

What is a ClusterRole?

A ClusterRole is similar to a Role but applies permissions cluster-wide instead of being restricted to a specific namespace.

What is a ClusterRoleBinding?

A ClusterRoleBinding associates a ClusterRole with a user, group, or service account, granting them the specified permissions at the cluster level.

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Use Cases

ClusterRole and ClusterRoleBinding are useful in various scenarios:

1. Granting Read-Only Access to All Namespaces

• Providing read-only permissions to developers for all cluster resources.

2. Managing Cluster-Wide Resources

• Controlling access to cluster-wide resources like nodes, persistent volumes, and namespaces.

3. Granting Admin Access Across Namespaces

• Assigning administrative privileges to users who need to manage resources across multiple namespaces.

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ClusterRole Syntax

A ClusterRole is created using the following YAML configuration:

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: cluster-admin-role
rules:
  - apiGroups: [""]
    resources: ["pods", "services", "nodes"]
    verbs: ["get", "list", "watch"]

This ClusterRole allows listing and reading Pods, Services, and Nodes across the cluster.

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ClusterRoleBinding Syntax

A ClusterRoleBinding links a ClusterRole to a user, group, or service account.

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: cluster-admin-binding
subjects:
  - kind: User
    name: john-doe
    apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: ClusterRole
  name: cluster-admin-role
  apiGroup: rbac.authorization.k8s.io

This binding grants the user john-doe the permissions defined in cluster-admin-role across the cluster.

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Removing ClusterRole and ClusterRoleBinding

To delete a ClusterRole:

kubectl delete clusterrole cluster-admin-role

To delete a ClusterRoleBinding:

kubectl delete clusterrolebinding cluster-admin-binding

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Conclusion

ClusterRole and ClusterRoleBinding are essential for managing cluster-wide access in Kubernetes. They provide fine-grained permissions across all namespaces, ensuring secure access control and resource management.

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In My Previous Role

As a Senior DevOps Engineer, I utilized Kubernetes ClusterRoles and ClusterRoleBindings for efficient access management:

• Read-Only Access: Assigned ClusterRoles for developers to inspect cluster-wide resources without modification rights.

• Cluster-Wide Management: Used ClusterRoles for managing node-level permissions and security configurations.

• Admin Access Control: Configured ClusterRoleBindings to enforce least privilege access while ensuring smooth operations.

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