@iin-mdc/koa-utils/middleware/ctx-logger.js

"use strict"
const { v4: makeUuid } = require("uuid")
const reqIdHeader              = "X-Request-Id"

module.exports = function createCtxLogger(logger) {
  const errorHandler         = initErrorHandler()
  const logMiddleware        = initLogMiddleware(logger, errorHandler)

  return logMiddleware
}

function initLogMiddleware(logger, errorHandler) {
  return async (ctx, next) => {
    const reqId       = ctx.reqId = ctx.request.get(reqIdHeader) || makeUuid()
    const log          = logger.child(reqId)
    const requestTimer = log.timer()

    ctx.log            = log
    ctx.requestTimer   = requestTimer
    
    try {
      await next()
    } catch (e) {
      await errorHandler(ctx, e)
    } finally {
      ctx.response.set("X-Server-Request-Id", ctx.reqId)
      ctx.requestTimer.end("%s %s > %d", ctx.request.method, ctx.request.url, ctx.response.status)
    }
  }
}

function initErrorHandler() {
  const handler = async (ctx, e) => {
    if (e instanceof Error === false) {
      e = new Error(e)
    }

    if (!e.status)   e.status   = 500
    if (!e.jsonBody) e.jsonBody = {}

    ctx.type   = "json"
    ctx.status = e.status

    ctx.log.error("%s %s < params: %O, body: %O", ctx.request.method, ctx.request.url, ctx.params, ctx.request.body)

    if (!e.expose) {
      const requestInformation = {
        method:        ctx.method,
        url:           ctx.url,
        userAgent:     ctx.request.get("user-agent"),
        referrer:      ctx.request.get("referrer"),
        statusCode:    ctx.status,
        remoteAddress: ctx.ip,
        requestId:     ctx.request.get("x-request-id") }
      ctx.log.error(e, requestInformation)
    }

    e.jsonBody.status  = e.status
    e.jsonBody.message = e.expose ? e.message : "Error"

    ctx.body = {
      error: e.jsonBody,
      reqId: ctx.reqId
    }
  } 
  return handler
}