@kasifraza/nestjs-logger

Structured JSON logger for NestJS with request tracing, correlation IDs, and per-module log levels. Zero dependencies beyond NestJS.

Install

npm install @kasifraza/nestjs-logger

Setup

// main.ts
import { StructuredLogger, LoggingInterceptor } from '@kasifraza/nestjs-logger';

const app = await NestFactory.create(AppModule, { logger: new StructuredLogger() });
app.useGlobalInterceptors(new LoggingInterceptor());

// app.module.ts
import { MiddlewareConsumer, Module } from '@nestjs/common';
import { CorrelationIdMiddleware } from '@kasifraza/nestjs-logger';

@Module({})
export class AppModule {
  configure(consumer: MiddlewareConsumer) {
    consumer.apply(CorrelationIdMiddleware).forRoutes('*');
  }
}

Features

• Structured JSON output — machine-parseable logs for CloudWatch/ELK/Datadog
• Correlation IDs — auto-generated or passed via x-correlation-id header
• Request tracing — method, path, status code, duration auto-logged
• Log levels — debug, info, warn, error with filtering
• AsyncLocalStorage — correlation ID available anywhere without passing through params
• Zero config — works out of the box, configurable when needed

Log Output

{
  "timestamp": "2024-01-01T00:00:00.000Z",
  "level": "info",
  "message": "← GET /users 200 12ms",
  "context": "HTTP",
  "correlationId": "550e8400-e29b-41d4-a716-446655440000",
  "requestId": "7c9e6679-7425-40de-944b-e07fc1f90ae7"
}

API

StructuredLogger

const logger = new StructuredLogger({
  level: 'info',      // 'debug' | 'info' | 'warn' | 'error'
  pretty: false,      // pretty-print JSON (auto: true in dev)
  context: 'MyService'
});

logger.log('message');
logger.warn('message');
logger.error('message', 'stack trace');
logger.debug('message');

CorrelationIdMiddleware

Attaches correlation ID to every request via AsyncLocalStorage. Reads from x-correlation-id header or generates a new UUID.

LoggingInterceptor

Auto-logs incoming requests and outgoing responses with duration.

getCorrelationId()

Get the current correlation ID from anywhere:

import { getCorrelationId } from '@kasifraza/nestjs-logger';

const id = getCorrelationId(); // works in services, repositories, etc.

getRequestContext()

Get full request context:

import { getRequestContext } from '@kasifraza/nestjs-logger';

const ctx = getRequestContext();
// { correlationId, requestId, method, path, startTime, userId }

Environment Variables

| Variable | Default | Description | |----------|---------|-------------| | LOG_LEVEL | info | Minimum log level | | NODE_ENV | — | When production, disables pretty-print |

License

MIT