koa日志中间件

// 安装log4js
npm install log4js --save-dev

// log.ts
import Koa from ‘koa‘
import log4js from ‘log4js‘

const env = process.env.NODE_ENV

log4js.configure({
  appenders: {
    everything: {
      type: ‘dateFile‘,
      filename: ‘./logs/day‘,
      pattern: ‘yyyy-MM-dd.log‘,
      alwaysIncludePattern: true,
      keepFileExt: true,
      daysToKeep: 7
    },
    dev: {
      type: ‘console‘
    }
  },
  categories: {
    default: {
      appenders: [‘everything‘],
      level: ‘info‘
    },
    dev: {
      appenders: [‘dev‘, ‘everything‘],
      level: ‘debug‘
    }
  }
})

let logger = env !== ‘production‘
  ? log4js.getLogger(‘dev‘)
  : log4js.getLogger()

export default async function (ctx: Koa.Context, next: Koa.Next) {
  ctx.logger = logger

  try {
    // 放行请求，以捕捉请求内异常
    await next()

    if (ctx.status === 404) {
      ctx.throw(404);
    }

    // 记录大于200的错误
    const ctxBody = ctx.body as IResult
    if (ctxBody.code > 200) {
      logger.info(JSON.stringify({
        url: ctx.url,
        message: ctxBody.message
      }))
    }
  } catch (error: any) {
    // 记录异常日志
    logger.error(JSON.stringify({
      url: ctx.url,
      error: error.message
    }))
  }
}