# Logging — Fastify: Building High-Performance Node.js APIs

Source: https://www.skillbyai.com/en/fastify/ff-logging

> Use Pino structured logging in Fastify with request-scoped loggers and meaningful log levels.

## Pino: fast structured logging

Fastify comes with Pino, a high-performance JSON logger. Access it via `fastify.log` in routes and plugins.

## Logging with context

Log with structured data for better debugging and monitoring.

```javascript
fastify.get('/users/:id', async (req, reply) => {
  fastify.log.info({
    userId: req.params.id,
    method: req.method,
    timestamp: new Date().toISOString(),
  }, 'Fetching user');
  
  try {
    const user = await findUser(req.params.id);
    return user;
  } catch (err) {
    fastify.log.error({
      userId: req.params.id,
      error: err.message,
    }, 'Failed to fetch user');
    throw err;
  }
});
```

Quick check

**Quiz:** How do you turn on the built-in Pino logger?

- [x] `Fastify({ logger: true })`
- [ ] `npm i pino` only
- [ ] It is always on

*Answer:* `Fastify({ logger: true })`. Logging is off by default; `logger: true` enables Pino with per-request ids.