fastify-best-practices

## When to use Use this skill when you need to: - Develop backend applications using Fastify - Implement Fastify plugins and route handlers - Get guidance on Fastify architecture and patterns - Use TypeScript with Fastify (strip types) - Implement testing with Fastify's inject method - Configure validation, serialization, and error handling ## Quick Start A minimal, runnable Fastify server to get started immediately: ```ts import Fastify from 'fastify' const app = Fastify({ logger: true }) app.get('/health', async (request, reply) => { return { status: 'ok' } }) const start = async () => { await app.listen({ port: 3000, host: '0.0.0.0' }) } start() ``` ## Recommended Reading Order for Common Scenarios - **New to Fastify?** Start with `plugins.md` → `routes.md` → `schemas.md` - **Adding authentication:** `plugins.md` → `hooks.md` → `authentication.md` - **Improving performance:** `schemas.md` → `serialization.md` → `performance.md` - **Setting up testing:** `routes.md` → `testing.md` - **Going to production:** `logging.md` → `configuration.md` → `deployment.md` ## How to use Read individual rule files for detailed explanations and code examples: - [rules/plugins.md](rules/plugins.md) - Plugin development and encapsulation - [rules/routes.md](rules/routes.md) - Route organization and handlers - [rules/schemas.md](rules/schemas.md) - JSON Schema validation - [rules/error-handling.md](rules/error-handling.md) - Error handling patterns - [rules/hooks.md](rules/hooks.md) - Hooks and request lifecycle - [rules/authentication.md](rules/authentication.md) - Authentication and authorization - [rules/testing.md](rules/testing.md) - Testing with inject() - [rules/performance.md](rules/performance.md) - Performance optimization - [rules/logging.md](rules/logging.md) - Logging with Pino - [rules/typescript.md](rules/typescript.md) - TypeScript integration - [rules/decorators.md](rules/decorators.md) - Decorators and extensions - [rules/content-type.md](rules/content-type.md) - Content type parsing - [rules/serialization.md](rules/serialization.md) - Response serialization - [rules/cors-security.md](rules/cors-security.md) - CORS and security headers - [rules/websockets.md](rules/websockets.md) - WebSocket support - [rules/database.md](rules/database.md) - Database integration patterns - [rules/configuration.md](rules/configuration.md) - Application configuration - [rules/deployment.md](rules/deployment.md) - Production deployment - [rules/http-proxy.md](rules/http-proxy.md) - HTTP proxying and reply.from() ## Core Principles - **Encapsulation**: Fastify's plugin system provides automatic encapsulation - **Schema-first**: Define schemas for validation and serialization - **Performance**: Fastify is optimized for speed; use its features correctly - **Async/await**: All handlers and hooks support async functions - **Minimal dependencies**: Prefer Fastify's built-in features and official plugins