Logger

Bueno's logger provides structured, leveled logging with context propagation, custom formatters, and transport adapters.

Basic usage

import { createLogger } from '@buenojs/bueno/logger';

const logger = createLogger({ name: 'myapp' });

logger.debug('Starting initialization');
logger.info('Server started', { port: 3000 });
logger.warn('Slow query detected', { duration: 1234, query: 'SELECT ...' });
logger.error('Database connection failed', { error: err.message });

Log levels

Level	When to use
`debug`	Verbose development info
`info`	Normal operational events
`warn`	Something unexpected but non-fatal
`error`	Errors that need attention
`fatal`	Application cannot continue

Set the minimum level via config or environment:

const logger = createLogger({
  name: 'myapp',
  level: process.env.LOG_LEVEL ?? 'info',
});

Structured context

Attach context that appears in every log message:

const requestLogger = logger.child({
  requestId: ctx.get('requestId'),
  userId: ctx.get('user')?.id,
});

requestLogger.info('Processing payment', { amount: 42.5 });
// → { level: "info", name: "myapp", requestId: "...", userId: 1, amount: 42.5, message: "Processing payment" }

Middleware integration

Log every request automatically:

import { requestLogger } from '@buenojs/bueno/middleware';

app.use(requestLogger({ logger }));

Output format:

GET /api/users 200 12ms
POST /api/posts 201 45ms
GET /api/missing 404 3ms

Formatters

JSON (default, recommended for production)

const logger = createLogger({
  name: 'myapp',
  formatter: 'json',
});

Pretty (development)

const logger = createLogger({
  name: 'myapp',
  formatter: 'pretty',  // Colorized, human-readable
});

Custom

const logger = createLogger({
  name: 'myapp',
  formatter: (entry) => `[${entry.level.toUpperCase()}] ${entry.message}`,
});

Transports

Write logs to multiple destinations:

const logger = createLogger({
  name: 'myapp',
  transports: [
    { type: 'console' },
    { type: 'file', path: './logs/app.log' },
    { type: 'file', path: './logs/error.log', level: 'error' },
  ],
});

Error logging

Log errors with full stack traces:

try {
  await riskyOperation();
} catch (err) {
  logger.error('Operation failed', {
    error: err instanceof Error ? err.message : String(err),
    stack: err instanceof Error ? err.stack : undefined,
  });
}