@infra-node-kit/logger provides common abilities for all Node.js application to log with some pre-defined rules (format, properties .etc).

Install

yarn add @infra-node-kit/logger

Get Start

import { logger, createLogger, LOG_LEVEL, createLoggerService } from '@infra-node-kit/logger'

// use predefined logger
logger.debug('my debug message')

// create logger with options
const myLogger = createLogger({
  level: LOG_LEVEL.WARN,
})

try {
  // throw error
} catch (e) {
  // log error stack
  myLogger.stack(e)
}

// log normal message with stack
myLogger.stack('normal message')

const newLogger = myLogger.extends({
  host: 'localhost:3000'
})
// { message: 'extended', host: 'localhost:3000' }
newLogger.info('extended')

const loggerSerivce = createLoggerService({
  // ...
})
app.useLogger(loggerService)

User Stories

Story 1: print messages both in console and files under ./logs, with default format

import { logger } from '@infra-node-kit/logger'

logger.info('messsage')
logger.info({
  message: 'message',
  customField: 'this is a custom field in log'
})
logger.error('critical error', { customField: 'this is a custom field in log' })

Story 2: print errors or messages with call stack

import { logger } from '@infra-node-kit/logger'

try {
  doSomeDangerousOperations()
} catch (e) {
  logger.stack(e)
}

function foo() {
  // ...

  // want to print call stack here
  logger.stack('I\'m in foo function')

  // ...
}

Story 3: replace logger in nestjs

import { NestFactory } from '@nestjs/core'
import { createLoggerService } from '@infra-node-kit/logger'
import MainModule from './main.module'

const app = await NestFactory.create(MainModule)

const loggerService = createLoggerService()
app.useLogger(loggerService)

Story 4: print messages with custom format

import { createLogger, LOG_FORMAT } from '@infra-node-kit/logger'

const logger = createLogger({
  format: LOG_FORMAT.CUSTOM,
  renderLog: (params: IGeneralLogParams) => {
    return Object.entries(params).map(([key, value]) => `${key}=${value}`).join(' ')
  },
})

logger.info('my message') // level=info message=my message

Story 5: use nestjs logger

import { NestFactory } from '@nestjs/core'
import { Injectable } from '@nestjs/common'
import { createLoggerService, LoggerService } from '@infra-node-kit/logger'
import { MainModule } from './main.module'

const app = await NestFactory.create(MainModule);
app.useLogger(createLoggerService())

@Injectable()
export class FooService {
  constructor(private logger: LoggerService) {}

  bar() {
    this.logger.info('log with x-request-id')
  }
}

Story 6: use decorator

The parameter of @Logger() can be a string as service or an object as extends fields.

Notice: DO NOT use @Logger() in constructor, it's not a nestjs injection.

import { Logger } from '@infra-node-kit/logger'

@Injectable()
export class FooService {
  @Logger('biz') private logger: LoggerService

  bar() {
    this.logger.info('log with x-request-id')
  }
}

API References

API References

• createLogger
• ICreateLoggerOptions
• ILogger

type ILogger = {
  error(message: string | IGeneralLogParams, fields?: IGeneralLogParams): ILogger;
  warn(message: string | IGeneralLogParams, fields?: IGeneralLogParams): ILogger;
  info(message: string | IGeneralLogParams, fields?: IGeneralLogParams): ILogger;
  debug(message: string | IGeneralLogParams, fields?: IGeneralLogParams): ILogger;
  trace(message: string | IGeneralLogParams, fields?: IGeneralLogParams): ILogger;

  stack(error?: Error | any): ILogger;
  extends(fields: IGeneralLogParams): ILogger;
}

function createLogger(options?: ICreateLoggerOptions): ILogger;

interface ICreateLoggerOptions {
  /** Print log above this level only */
  level?: LogLevel
  /** Select format of log */
  format?:
    | LOG_FORMAT
    | {
        console?: LOG_FORMAT
        file?: LOG_FORMAT
      }
  /** Render custom format log */
  renderLog?: (params: IGeneralLogParams) => string
  /** Fields appended to every log */
  extends?: IGeneralLogParams
  /** Don't print warning messages of this package */
  silent?: boolean
  /** Disable printing log to console */
  disableConsole?: boolean
  /** Disable printing log to file */
  disableFile?: boolean
  /**
   * Options in `winston-daily-rotate-file`
   * `dirname` is default to './logs'
   */
  rotateFileOptions?: GeneralDailyRotateFileTransportOptions
}

extends action field

declare module '@infra-node-kit/logger' {
  interface ILogActions {
    'fetch': 'for fetch'
    'access': 'access log'
  }
}

fetch and access will be valid values in field action