How do you manage user authentication in cloud-native applications?

Cloud-native applications adopt a dynamic microservices architecture, making traditional monolithic authentication no longer applicable. User authentication is the cornerstone of their security, requiring support for cross-service and cross-cluster scenarios, and the application of the zero-trust principle. Its importance lies in ensuring secure access, compliance, and a seamless user experience, which is crucial for accessing APIs, web applications, and internal and external systems.

Core components include: OAuth 2.0 and OpenID Connect (OIDC) protocols, JSON Web Tokens, and Service Accounts. The principle relies on a centralized identity provider to handle authentication, with applications trusting the verifiable tokens it issues. In practical applications, IDPs (such as Keycloak, Auth0, Azure AD) are often integrated through sidecars (e.g., Istio), ingress controllers, or application-built SDKs, with tokens carrying claims for fine-grained access control.

Implementation steps: 1) Deploy or connect to an enterprise IDP and configure OIDC. 2) Integrate OIDC client libraries into applications or use service meshes to handle identities. 3) Use Kubernetes RBAC or policy engines to configure authorization rules based on JWT claims. Typical scenarios include single sign-on and inter-service authentication, bringing core business values such as unified security policies, simplified user management, and enhanced auditing capabilities.