@crypolt/crplogger

Lightweight, zero-dependency, high-performance asynchronous structured JSON logger for Node.js with automatic request_id propagation via AsyncLocalStorage.

Features

• Zero dependencies
• Asynchronous non-blocking queue
• Automatic request_id propagation
• Fully structured JSON logs
• Global logger instance (initLogger, getLogger)
• Works with Elastic, Loki, Kibana, Grafana
• Error stack trace serialization
• Minimal overhead and extremely fast

Installation

npm install @crypolt/crplogger

Quick Start

import { initLogger } from '@crypolt/crplogger'

const logger = initLogger({ level: 'INFO' })

logger.info('Server started', {
  Payload: { port: 8080 }
})

Example output:

2025-01-15T10:25:10.123Z {"Level":"INFO","Host":"app01","Message":"Server started","Payload":{"port":8080,"RequestID":"8e91a380-..."}}

Request ID Context

import { runWithRequestId, getRequestId, getLogger } from '@crypolt/crplogger'

runWithRequestId(() => {
  const logger = getLogger()
  logger.info('Inside context', {
    Payload: { id: getRequestId() }
  })
})

Global Logger

import { initLogger, getLogger } from '@crypolt/crplogger'

initLogger({ level: 'DEBUG' })

const logger = getLogger()

logger.debug('Debug message')
logger.error(new Error('Failure'))

API

initLogger(config)

Initialize global logger (singleton).

getLogger()

Returns the global logger instance.

createLogger(config)

Creates a standalone logger instance.

Logger Methods

• logger.trace(message, meta?)
• logger.debug(message, meta?)
• logger.info(message, meta?)
• logger.warn(message, meta?)
• logger.error(message or Error, meta?)
• logger.fatal(message or Error, meta?)

LogMeta structure

{
  Payload?: Record<string, any>,
  request_id?: string,
  stack?: string,
  errorMsg?: string,
  Source?: any
}

Integration Examples

Express

import express from 'express'
import { initLogger, runWithRequestId, getLogger } from '@crypolt/crplogger'

initLogger({ level: 'INFO' })

const app = express()

app.use((req, res, next) => {
  runWithRequestId(() => {
    const logger = getLogger()
    logger.info('Incoming request', {
      Payload: {
        method: req.method,
        url: req.url
      }
    })
    next()
  })
})

app.get('/', (req, res) => {
  const logger = getLogger()
  logger.info('Handled root route')
  res.send('OK')
})

app.listen(3000)

Fastify

import Fastify from 'fastify'
import { initLogger, runWithRequestId, getLogger } from '@crypolt/crplogger'

initLogger({ level: 'INFO' })

const app = Fastify()

app.addHook('onRequest', (req, res, next) => {
  runWithRequestId(() => {
    const logger = getLogger()
    logger.info('Incoming request', {
      Payload: { url: req.url }
    })
    next()
  })
})

app.get('/', async () => {
  const logger = getLogger()
  logger.info('Fastify root hit')
  return { ok: true }
})

app.listen({ port: 3000 })

Kafka Consumer

import { Kafka } from 'kafkajs'
import { initLogger, runWithRequestId, getLogger } from '@crypolt/crplogger'

initLogger({ level: 'INFO' })

const kafka = new Kafka({ clientId: 'svc', brokers: ['localhost:9092'] })
const consumer = kafka.consumer({ groupId: 'group1' })

await consumer.connect()
await consumer.subscribe({ topic: 'events' })

await consumer.run({
  eachMessage: async ({ message }) => {
    runWithRequestId(() => {
      const logger = getLogger()
      logger.info('Processing message', {
        Payload: { value: message.value.toString() }
      })
    })
  }
})

Example Log Output

2025-01-15T10:30:12.114Z {"Level":"INFO","Host":"srv01","Message":"Incoming request","Payload":{"method":"GET","url":"/","RequestID":"d59f5e1b-..."}}
2025-01-15T10:30:12.115Z {"Level":"INFO","Host":"srv01","Message":"Handled root route","Payload":{"RequestID":"d59f5e1b-..."}}

License

Information / Contact

-- telegram @crypolt

MIT License