nestx-log4js

Provide log4js module as NestJS module

This is root of @nestx-log4js monorepo.

To Get Started, please read @nestx-log4js/core Documentation

Core Module Documentation

log4js as NestJS Module.

Features

• Provide log4js wrapper as NestJS Global Module
• Provide Log4jsLogger instance for replacement logger usage

Installation

yarn add @nestx-log4js/core

Usage

Just want to use log4js?

Since logger is a special service in NestJS, we suppose import Log4jsModule and manual call app.useLogger(app.get(Log4jsLogger))

app.module.ts

import { Module } from '@nestjs/common';
import { Log4jsModule } from '@nestx-log4js/core';


@Module({
  imports: [
    Log4jsModule.forRoot()
  ]
})
export class AppModule {}

bootstrap.ts

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module'; 
import { Log4jsLogger } from '@nestx-log4js/core';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  
  app.useLogger(app.get(Log4jsLogger));
  await app.listen(3000);
}
bootstrap();

For more details, you can refer unit tests in source code

Initial Log4jsModule with AsyncOptions (Production Usage)

You might want to use different appender (e.g. file/dateFile appender) in real production usage and initial in your ConfigService/LoggerOnlyConfigService

app.module.ts

import { Module } from '@nestjs/common';
import { Log4jsModule } from '@nestx-log4js/core';

// import your ConfigService/LoggerConfigService

@Module({
  imports: [
    Log4js.forRootAsync({
      inject: [ConfigService],
      useFactory: (config: ConfigService) => config.getLog4jsOptions() // config.getLog4jsOptions should return valid Log4jsOptions
    })
  ]
})
export class AppModule {}

Bundled Layout & Appenders

When using Log4jsModule.forRoot() and no spec any appenders and layouts,

It will use default below layouts:

export const LOG4JS_DEFAULT_LAYOUT = {
  type: 'pattern',
  // log4js default pattern %d{yyyy-MM-dd HH:mm:ss:SSS} [%thread] %-5level %logger{36} - %msg%n
  // we use process id instead thread id
  pattern: '%[%d{yyyy-MM-dd hh:mm:ss:SSS} %p --- [%15.15x{name}]%] %40.40f{3}  : %m',
  tokens: {
    name: (logEvent) => {
      return (logEvent.context && logEvent.context['name']) || '-';
    }
  }
};

export const LOG4JS_NO_COLOUR_DEFAULT_LAYOUT = {
  type: 'pattern',
  // log4js default pattern %d{yyyy-MM-dd HH:mm:ss:SSS} [%thread] %-5level %logger{36} - %msg%n
  // we use process id instead thread id
  pattern: '%d{yyyy-MM-dd hh:mm:ss:SSS} %p --- [%15.15x{name}] %40.40f{3}  : %m',
  tokens: {
    name: (logEvent) => {
      return (logEvent.context && logEvent.context['name']) || '-';
    }
  }
};



export const LOG4JS_DEFAULT_CONFIG: Configuration = {
  appenders: {
    stdout: {
      type: 'stdout',
      layout: LOG4JS_DEFAULT_LAYOUT
    },
    file: {
      type: 'file',
      filename: './logs/application.log',
      maxLogSize: 20 * 1024 * 1024, // maxLogSize use bytes ad unit
      backups: 10,     // default use 5 so 1KB file size total rotating
      layout: LOG4JS_NO_COLOUR_DEFAULT_LAYOUT
    }
  },
  categories: {
    default: {
      enableCallStack: true,
      appenders: ['stdout', 'file'],
      level: 'debug'
    }
  }
};

It will use default below layouts (from spring boot default log pattern without process id)

You can refer to SpringBoot logging features

2020-11-14 15:47:24:486 INFO --- [         NestJS]               core/src/log4js.classes.ts  : log using nestjs as category
2020-11-14 15:47:24:486 INFO --- [              -]               core/src/log4js.classes.ts  : log using none as category
2020-11-14 15:47:24:490 INFO --- [         NestJS]               core/src/log4js.classes.ts  : log using nestjs as category
2020-11-14 15:47:24:490 WARN --- [              -]      src/__tests__/log4js.module.test.ts  : log using none as category

Tips: You are using grok pattern via filebeat/other sidecar log agent? You can use below grok pattern: %{TIMESTAMP_ISO8601:server_time}\s*%{LOGLEVEL:level}\s*---\s*[\s*%{NOTSPACE:context}]\s*%{NOTSPACE:file_path}\s*:\s*%{GREEDYDATA:content}

It will split to friendly format (you can update alias yourself via grok document)

• server_time
• level
• context
• file_path
• content