Microservice pattern: Access token #2689

Description:
The Access Token design pattern is crucial for managing secure communication between microservices. This pattern involves the use of tokens, typically JWT (JSON Web Tokens), to verify the identity and permissions of a user or service making a request to another service. Implementing this pattern enhances security, scalability, and maintainability of microservices by decoupling authentication logic from individual services.

Main Elements:

1. Token Issuance: A trusted authority (Authorization Server) issues tokens after authenticating a user or service.
2. Token Validation: Microservices validate the tokens to ensure the request is authenticated and authorized.
3. Token Scope and Permissions: Tokens carry claims about the user's identity and permissions, defining what resources and operations the user is allowed to access.
4. Token Expiry and Refresh: Tokens have a limited lifespan, and mechanisms must be in place to refresh tokens when they expire.
5. Security Measures: Implementing security measures to protect tokens in transit and at rest, including the use of HTTPS and secure storage.

References:

• Microservices Security Patterns
• OAuth 2.0 and OpenID Connect
• JSON Web Tokens (JWT)
• Spring Security OAuth2

Acceptance Criteria:

1. Implement a token issuance mechanism using a trusted Authorization Server.
2. Ensure microservices can validate the tokens received in incoming requests.
3. Define token scopes and permissions to control access to different resources and operations.
4. Implement token expiry and refresh mechanisms to manage token lifecycle.
5. Ensure all communication involving tokens is secure, using HTTPS and appropriate storage solutions for tokens.

Please ensure adherence to the project contribution guidelines while working on this issue.