pino

name	pino
description	Guides AI agents to use Pino logging correctly — levels, structured logs, child loggers, and Fastify integration.
metadata	{"tags":["pino","logging","fastify","nodejs"]}

Pino Skill

Use this skill when writing any logging code with Pino: creating loggers, choosing log levels, adding context, or configuring Fastify's built-in logger.

When to Use

• Configuring the Fastify logger at startup
• Adding log statements to route handlers, plugins, or services
• Creating child loggers with bound context
• Logging errors with full detail
• Configuring log output for development vs. production

Rules

1. rules/levels.md — When to use each log level (trace, debug, info, warn, error, fatal).
2. rules/structured-logging.md — How to write structured log entries with context objects.
3. rules/child-loggers.md — Creating child loggers to bind persistent context (request ID, user ID, module name).
4. rules/fastify-integration.md — Fastify logger configuration, request.log, and serializers.

Quick Reference

// Fastify uses Pino by default — enable it at startup
const app = Fastify({ logger: true });

// In route handlers, always use request.log (bound to request id)
fastify.get('/users/:id', async (request) => {
  request.log.info({ userId: request.params.id }, 'fetching user');
  const user = await db.findUser(request.params.id);
  if (!user) {
    request.log.warn({ userId: request.params.id }, 'user not found');
    throw fastify.httpErrors.notFound();
  }
  return user;
});

// Log errors with the err key — Pino serializes Error objects automatically
try {
  await riskyOp();
} catch (err) {
  request.log.error({ err }, 'riskyOp failed');
  throw err;
}