Node.js 模块之 morgan中间件记录日志

NodeJs中Express框架使用morgan中间件记录日志

Express中的app.js文件已经默认引入了该中间件var logger = require('morgan');

使用app.use(logger('dev'));可以将请求信息打印在控制台，便于开发调试，但实际生产环境中，需要将日志记录在log文件里，可以使用如下代码

    var express = require('express');  
    var fs = require('fs');  
    var logger = require('morgan');  
      
    var app = express();  
      
    var accessLog = fs.createWriteStream('../access.log', {flags : 'a'});  
    var errorLog = fs.createWriteStream('../error.log', {flags : 'a'});  
      
    app.use(logger('dev'));     //打印到控制台  
    app.use(logger('combined', {stream : accessLog}));      //打印到log日志  

这样便可以将请求信息打印在根目录下的access.log文件中（注意文件路径别填错，并不会自动创建该文件）

示例：

express/connect

Simple app that will log all request in the Apache combined format to STDOUTq

Log出所有Apache请求（结合STTDOUT格式）

var express = require('express')
var morgan = require('morgan')
 
var app = express()
 
app.use(morgan('combined'))
 
app.get('/', function (req, res) {
  res.send('hello, world!')
})

vanilla http server

Simple app that will log all request in the Apache combined format to STDOUT

var finalhandler = require('finalhandler')
var http = require('http')
var morgan = require('morgan')
 
// create "middleware"
var logger = morgan('combined')
 
http.createServer(function (req, res) {
  var done = finalhandler(req, res)
  logger(req, res, function (err) {
    if (err) return done(err)
 
    // respond to request
    res.setHeader('content-type', 'text/plain')
    res.end('hello, world!')
  })
})

write logs to a file

single file

Simple app that will log all requests in the Apache combined format to the file access.log.

Log列出所有Apache请求到access.log中

var express = require('express')
var fs = require('fs')
var morgan = require('morgan')
var path = require('path')
 
var app = express()
 
// create a write stream (in append mode)
var accessLogStream = fs.createWriteStream(path.join(__dirname, 'access.log'), {flags: 'a'})
 
// setup the logger
app.use(morgan('combined', {stream: accessLogStream}))
 
app.get('/', function (req, res) {
  res.send('hello, world!')
})

log file rotation

Simple app that will log all requests in the Apache combined format to one log file per day in the log/ directory using the rotating-file-stream module.

每天将所有Apache请求记录到log中

var express = require('express')
var fs = require('fs')
var morgan = require('morgan')
var path = require('path')
var rfs = require('rotating-file-stream')
 
var app = express()
var logDirectory = path.join(__dirname, 'log')
 
// ensure log directory exists
fs.existsSync(logDirectory) || fs.mkdirSync(logDirectory)
 
// create a rotating write stream
var accessLogStream = rfs('access.log', {
  interval: '1d', // rotate daily
  path: logDirectory
})
 
// setup the logger
app.use(morgan('combined', {stream: accessLogStream}))
 
app.get('/', function (req, res) {
  res.send('hello, world!')
})

split / dual logging

The morgan middleware can be used as many times as needed, enabling combinations like:

• Log entry on request and one on response
• Log all requests to file, but errors to console
• ... and more!

Sample app that will log all requests to a file using Apache format, but error responses are logged to the console:

Log所有Apache请求，错误Log到console中

var express = require('express')
var fs = require('fs')
var morgan = require('morgan')
var path = require('path')
 
var app = express()
 
// log only 4xx and 5xx responses to console
app.use(morgan('dev', {
  skip: function (req, res) { return res.statusCode < 400 }
}))
 
// log all requests to access.log
app.use(morgan('common', {
  stream: fs.createWriteStream(path.join(__dirname, 'access.log'), {flags: 'a'})
}))
 
app.get('/', function (req, res) {
  res.send('hello, world!')
})

use custom token formats

Sample app that will use custom token formats. This adds an ID to all requests and displays it using the :id token.

ID Token格式

var express = require('express')
var morgan = require('morgan')
var uuid = require('node-uuid')
 
morgan.token('id', function getId (req) {
  return req.id
})
 
var app = express()
 
app.use(assignId)
app.use(morgan(':id :method :url :response-time'))
 
app.get('/', function (req, res) {
  res.send('hello, world!')
})
 
function assignId (req, res, next) {
  req.id = uuid.v4()
  next()
}