winston 日志模块

在使用 nodejs winston 模块中，加上相关的两个模块，事倍功半。

• express-winston
• winston-daily-rotate-file

express-winston

是 express-winston 的 winston 的增加版， 是作为 express 的中间件来打印日志，不仅有请求头信息，并且有响应时间。
作为中间件， 为什么会有响应时间呢？ 因为 express-winston 改写了 express 的 res.end 办法， 是请求结束后再打的日志。

代码片段

var end = res.end;
res.end = function(chunk, encoding) {
    res.responseTime = (new Date) - req._startTime;
    res.end = end;
    res.end(chunk, encoding);
    ...
    }

express-winston 没有修改或者扩展 winston 的transport， 而 winston-daily-rotate-file 正是增强了 winston 的transport 办法

winston-daily-rotate-file

winston-daily-rotate-file 是 winston 扩展， 增加了 transport 的办法，使 winston 有滚动日志的能力。

结合使用

我们来一个需求： 如何让 express-winston 打印日志的时候，也打印出接口 /api 的请求参数和响应数据？

• 该日志中间件应该在调用链 api 后面， api／* 业务处理之前。 like： app.use('/api', apiRequestLogger, apiHandler)
• 要获取到响应数据， 就要在业务处理完后 send 出来后才能捕获到，express 所有的请求响应最后都是走 res.send 我们可以从这里入手捕获响应数据

代码如下

import winston from 'winston'
import expressWinston from 'express-winston'
import 'winston-daily-rotate-file'
import path from 'path'

export let DailyRotateFileTransport = (fileName) => {
  return new (winston.transports.DailyRotateFile)({
    filename: path.join(process.env.LOGPATH, `${fileName}-%DATE%.log`),
    datePattern: 'YYYY-MM-DD-HH',
    // maxSize: '20m',
    maxFiles: '7d',
    timestamp: () => new Date().format('yyyy-MM-dd hh:mm:ss.S')
  })
}

export let pageRequestLogger = expressWinston.logger({
  transports: [
    DailyRotateFileTransport('page-request')
  ],
  meta: true, // optional: control whether you want to log the meta data about the request (default to true)
  msg: 'HTTP {{req.method}} {{req.url}}', // optional: customize the default logging message. E.g. "{{res.statusCode}} {{req.method}} {{res.responseTime}}ms {{req.url}}"
  expressFormat: true, // Use the default Express/morgan request formatting. Enabling this will override any msg if true. Will only output colors with colorize set to true
  colorize: false, // Color the text and status code, using the Express/morgan color palette (text: gray, status: default green, 3XX cyan, 4XX yellow, 5XX red).
  ignoreRoute: function (req, res) {
    // 只打印页面请求信息
    let notPageRequest = false
    let ignoreArr = ['/api', '.js', '.css', '.png', '.jpg', '.gif']
    ignoreArr.forEach(item => {
      if (req.url.indexOf(item) > -1) notPageRequest = true
    })
    return notPageRequest
  } // optional: allows to skip some log messages based on request and/or response
})

export let apiRequestLogger = (req, res, next) => {
  let send = res.send
  let content = ''
  let query = req.query || {}
  let body = req.body || {}
  res.send = function () {
    content = arguments[0]
    send.apply(res, arguments)
  }
  expressWinston.logger({
    transports: [
      DailyRotateFileTransport('api-request')
    ],
    meta: true, // optional: control whether you want to log the meta data about the request (default to true)
    msg () {
      return `HTTP ${req.method} ${req.url} query ${JSON.stringify(query)} body ${JSON.stringify(body)} resData ${content} `
    },
    colorize: true, // Color the text and status code, using the Express/morgan color palette (text: gray, status: default green, 3XX cyan, 4XX yellow, 5XX red).
    ignoreRoute: function (req, res) {
      if (req.headers.self) return true
      return false
    } // optional: allows to skip some log messages based on request and/or response
  })(req, res, next)
}