go-backend-microservices

---
name: go-backend-microservices
description: Go backend development best practices for microservices with clean architecture, observability, and production-ready patterns
---

# Go Backend Development for Microservices

## Core Principles

- Apply Clean Architecture with clear separation into handlers, services, repositories, and domain models
- Prioritize interface-driven development with explicit dependency injection
- Write short, focused functions with a single responsibility
- Ensure safe use of goroutines, and guard shared state with channels or sync primitives

## Project Structure

Maintain modular project structure with clear directories:

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

## Error Handling

- Always check and handle errors explicitly
- Use wrapped errors for traceability: `fmt.Errorf("context: %w", err)`
- Create custom error types for domain-specific errors
- Return errors up the call stack with appropriate context
- Log errors at the appropriate level with sufficient context

## Context Propagation

- Use context propagation for request-scoped values, deadlines, and cancellations
- Pass context as the first parameter to functions
- Respect context cancellation in long-running operations
- Set appropriate timeouts for external calls

## Observability

Implement OpenTelemetry for comprehensive observability:

### Distributed Tracing
- Add spans for significant operations
- Propagate trace context across service boundaries
- Include relevant attributes in spans

### Metrics
- Implement custom metrics for business operations
- Use standard metric types (counters, gauges, histograms)
- Export metrics in Prometheus format

### Structured Logging
- Use structured logging with consistent field names
- Include trace IDs in log entries
- Log at appropriate levels (debug, info, warn, error)

## Security

- Apply input validation rigorously on all external inputs
- Use secure defaults for JWT tokens and cookies
- Implement proper authentication and authorization
- Sanitize data before logging to avoid leaking sensitive information
- Use prepared statements for database queries

## Testing

### Unit Tests
- Write table-driven unit tests with adequate coverage
- Use parallel test execution where safe
- Mock external dependencies using interfaces
- Focus on testing business logic

### Integration Tests
- Separate integration tests from unit tests
- Use test containers for database and service dependencies
- Test actual API endpoints and responses

## Concurrency

- Use goroutines appropriately for concurrent operations
- Guard shared state with channels or sync primitives
- Implement proper graceful shutdown
- Use worker pools for bounded concurrency

## Documentation

- Document with GoDoc-style comments
- Keep comments up to date with code changes
- Document public APIs thoroughly
- Include examples in documentation where helpful

## CI/CD Integration

- Maintain CI integration for linting and testing
- Use golangci-lint for comprehensive linting
- Run tests on every pull request
- Include code coverage reporting