victorboissiere/n9-node-log

Logging node module based on Winston.

n9-node-log

Logging node module based on Winston.

Requirements

• NodeJS >= 8.0

Installation

npm install --save @neo9/n9-node-log

Usage

import n9Log from '@neo9/n9-node-log'

const log = n9Log('my-app-name')

// Write on stdout
log.verbose('This is a verbose message')
log.debug('This is a debug message')
log.info('This is an information message')
log.warn('Warning, this feature will be removed soon')
// Write on stderr
log.error('An error appened')

2017-05-12T15:57:14.474Z - info: [my-app-name] This is an information message
2017-05-12T15:57:14.689Z - warn: [my-app-name] Warning, this feature will be removed soon
2017-05-12T15:57:14.974Z - error: [my-app-name] An error appened

Metadata

log.info('Log with metadata', { anything: 'this is metadata' })
log.error('Here an error', new Error('hello'))

2017-05-12T15:57:14.474Z - info: [my-app-name] Log with metadata anything=this is metadata
2017-05-12T15:57:14.785Z - error: [node-ts-skeleton] Here an error Error: hello
    at Object.<anonymous> (/home/schopin/Neo9/node-ts-skeleton/src/index.ts:16:28)
    at Module._compile (module.js:571:32)
    at ...

Prefixing

const logUsers = log.module('users')

logUsers.info('Log specific to users module')

2017-05-12T15:57:14.474Z - info: [my-app-name:users] Log specific to users module

Profiling

log.profile('test')
setTimeout(() => log.profile('test'), 1000)

2017-05-12T15:57:14.474Z - info: [my-app-name] test durationMs=1000

Log level

You can filter the list of logs on startup with the N9LOG environment or with the level option.

Possible values:

• verbose: Display all logs
• debug: Display debug + info + warn + error logs
• info: Display info + warn + error logs
• warn: Display warn + error logs
• error: Display only error logs

Default value: verbose

Example: N9LOG=error node server.js will display only error logs.

Transports

Define the transporter(s) you want to use to store your logs, notice that you can combine them.

console

Will output the logs into process.stdout and process.stderr.

• Type: Boolean
• Default: true

Example:

const log = n9Log('my-app-name', {
  console: false, // Don't output the logs into the console
})

files

Will write the log output into specified file(s).

• Type: Array
• Default: []
• Properties:
  • level: Level of messages to write into the file (default: 'info')
  • filename: Path of the logfile
  • maxsize: Max sizes in bytes of the logfile
  • maxFiles: Limit the number of files created

Example:

const log = n9Log('my-app-name', {
  files: [
    {
      level: 'info',
      filename: '/tmp/info-log.log'
    }
  ]
})

http

• Type: Array
• Default: []
• Properties:
  • host: (Default: 'localhost') Remote host of the HTTP logging endpoint
  • port: (Default: 80 or 443) Remote port of the HTTP logging endpoint
  • path: (Default: '/') Remote URI of the HTTP logging endpoint
  • auth: (Default: None) An object representing the username and password for HTTP Basic Auth
  • ssl: (Default: false) Value indicating if we should us HTTPS

Example:

const log = n9Log('my-app-name', {
  http: [
    {
      host: 'my-logs.io',
      path: '/save',
      ssl: true
    }
  ]
})

transports

Useful for adding custom transports into n9-node-log:

• Type: Array
• Default: []

Example:

import * as WinstonElasticSearch from 'winston-elasticsearch'

const log = n9Log('test', {
  console: false,
  transports: [
    new WinstonElasticSearch({
      index: 'n9-log',
      level: 'info',
      mappingTemplate: require('winston-elasticsearch/index-template-mapping.json'),
      flushInterval: 200
    })
  ]
})