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) }