Build a simple RESTful API in Golang that manages a list of users. Use MongoDB for persistence, JWT for authentication, and follow clean code practices.

Each user should have:

• ID (auto-generated)
• Name (string)
• Email (string, unique)
• Password (hashed)
• CreatedAt (timestamp)

• Register a new user.
• Authenticate user and return a JWT.

• Use JWT for protecting endpoints.
• Use middleware to validate tokens.
• Use HMAC (HS256) with a secret key.

• Create a new user.
• Fetch user by ID.
• List all users.
• Update a user's name or email.
• Delete a user.

• Use the official Go MongoDB driver.
• Store and retrieve users from MongoDB.

• Logging middleware that logs HTTP method, path, and execution time.

• Run a background goroutine every 10 seconds that logs the number of users in the DB.

Write unit tests

Use Go’s testing package. Mock MongoDB where possible.

• Add Docker + docker-compose for API + MongoDB.
• Use Go interfaces to abstract MongoDB operations for testability.
• Add input validation (e.g., required fields, valid email).
• Implement graceful shutdown using context.Context.
• gRPC Version
  • Create a .proto file for CreateUser and GetUser.
  • Implement a gRPC server.
  • (Optional) Secure gRPC with token metadata.
• Hexagonal Architecture
  • Structure the project using hexagonal (ports & adapters) architecture:
    • Separate domain, application, and infrastructure layers.
    • Use interfaces for data access and external dependencies.
    • Keep business logic decoupled from frameworks and DB drivers.

• Submit a GitHub repo or zip file.
• Include a README.md with:
  • Project setup and run instructions
  • JWT token usage guide
  • Sample API requests/responses
  • Any assumptions or decisions made

• Code quality, structure, and readability
• REST API correctness and completeness
• JWT implementation and security
• MongoDB usage and abstraction
• Bonus: gRPC, Docker, validation, shutdown
• Testing coverage and mocking
• Use of idiomatic Go