AWS has moved away from the traditional config-based authentication for EKS clusters, advocating for API-based authentication instead. This article explains the underlying mechanism and benefits of this modern approach.
How API Authentication Works
The authentication flow involves multiple AWS services working in concert:
- Initial Request (Steps 1-2)
- kubectl initiates authentication using AWS credentials from standard locations (environment variables, AWS credentials file, or IAM roles)
- AWS STS verifies the identity and returns temporary credentials
- Permission Verification (Steps 3-4)
- IAM validates the user/role permissions for EKS access
- This ensures proper RBAC and security policies are enforced
- URL Generation (Steps 5-8)
- kubectl requests a presigned URL from EKS API server
- The URL is signed using AWS Signature Version 4
- EKS validates the IAM principal and permissions
- A time-limited presigned URL is returned
- Kubernetes Access (Steps 9-10)
- kubectl uses the presigned URL to access the Kubernetes API server
- The API server validates the URL and grants appropriate access
Benefits Over Config-Based Authentication
- Enhanced Security
- No persistent credentials stored in config files
- Fresh authentication on each request
- Automatic credential rotation
- Simplified Management
- Eliminates kubeconfig file management
- Reduces risk of stale or compromised credentials
- Seamless integration with AWS IAM
- Better Automation Support
- Ideal for CI/CD pipelines
- Works naturally with AWS IAM roles
- No need to manage kubeconfig files in automated environments
Best Practices
- IAM Role Configuration
- Use role-based access when possible
- Implement least-privilege permissions
- Regularly audit access patterns
- Authentication Flow
- Ensure proper AWS credential configuration
- Monitor API calls for security and debugging
- Implement proper error handling
- Migration Strategy
- Plan gradual transition from config-based authentication
- Update CI/CD pipelines to use API-based authentication
- Train teams on new authentication flow
Implementation Considerations
# No more need for: aws eks update-kubeconfig --name cluster-name --region region-name # Instead, ensure proper AWS credentials: export AWS_PROFILE=your-profile export AWS_REGION=your-region # kubectl will automatically use API authentication kubectl get pods
Conclusion
API-based authentication represents a more secure and maintainable approach to EKS cluster access. Understanding this mechanism is crucial for modern Kubernetes deployments on AWS, as it becomes the preferred authentication method.
Organizations should plan their migration to API-based authentication, taking advantage of its improved security posture and simplified credential management.