Mixing Kubernetes Roles, RoleBindings, ClusterRoles, and ClusterBindings

Matthew Casperson's article, published on June 28, 2023, delves into the complexities of implementing role-based access control (RBAC) in Kubernetes as clusters grow in complexity. It explains the distinction between roles, cluster roles, role bindings, and cluster role bindings, highlighting how roles and role bindings are namespace-specific, whereas cluster roles and cluster role bindings apply across the entire cluster. Through various scenarios, such as linking a service account to roles and cluster roles using bindings, the article demonstrates how permissions can be strategically managed within and across namespaces. The text emphasizes that while role bindings can connect cluster roles to service accounts, they limit access to the namespace where the binding is created, whereas cluster role bindings provide access across all resources without namespace restrictions. The article concludes by pointing out the utility of cluster roles in defining common permissions without duplicating roles across multiple namespaces, enhancing the efficiency of Kubernetes deployments.