---name: microservicesdescription: Guidelines for building production-grade microservices with FastAPI/Python and Go, covering serverless patterns, clean architecture, observability, and resilience.---

Microservices Development

You are an expert in microservices architecture with FastAPI/Python and Go.

Core Principles

• Design stateless services with external storage and caches (Redis)
• Implement API gateway patterns using NGINX, Traefik, or Kong
• Use circuit breakers and retry patterns for resilience
• Optimize for serverless deployment on AWS Lambda and Azure Functions

FastAPI Python Microservices

Asynchronous Processing

• Handle asynchronous tasks with Celery or RQ
• Implement proper task queuing and worker management
• Design for eventual consistency in distributed systems

Observability

• Use OpenTelemetry for distributed tracing
• Implement structured logging with ELK Stack integration
• Set up Prometheus and Grafana for monitoring and alerting
• Ensure correlation IDs propagate across service boundaries

Security

• Implement OAuth2 for authentication and authorization
• Apply rate limiting and DDoS protection
• Use Redis or Memcached for caching layers
• Validate all inputs at service boundaries

Go Backend Development for Microservices

Architecture

• Follow Clean Architecture pattern separating handlers, services, repositories, and domain models
• Apply domain-driven design principles
• Use interface-driven development with dependency injection
• Keep business logic in the domain layer, not in handlers

Project Structure

project/
  cmd/           # Application entry points
  internal/      # Private application code
  pkg/           # Public libraries
  api/           # API definitions (OpenAPI, protobuf)
  configs/       # Configuration files
  test/          # Additional test utilities

Error Handling

• Use explicit error handling with context wrapping
• Return errors with sufficient context for debugging
• Implement custom error types for domain-specific failures
• Never ignore errors silently

Concurrency

• Manage goroutines safely with proper lifecycle management
• Propagate context through all function calls
• Use channels appropriately for communication
• Implement graceful shutdown patterns

Testing

• Write comprehensive unit tests with table-driven patterns
• Use mocks for external dependencies
• Separate fast unit tests from integration tests
• Implement end-to-end tests for critical paths

Resilience

• Implement retries with exponential backoff
• Use circuit breakers to prevent cascade failures
• Design for graceful degradation
• Handle partial failures appropriately