koa-datadog-middleware/example.js

A koa middleware for reporting metrics to datadog

var ddog = require('./')
var koa = require('koa')
var app = koa()

app.use(ddog())

// 204

app.use(function *(next){
  if ('/204' == this.path) this.status = 204
  else yield next
})

// 404

app.use(function *(next){
  if ('/404/:bla' == this.path) return
  yield next
})

// destroy

app.use(function *(next){
  if ('/close' == this.path) return this.req.destroy()
  yield next
})

// compress the response 1/2 the time to calculate the stream length

app.use(function *(next){
  if (Math.random() > 0.5) {
    yield next
  } else {
    yield compress.call(this, next)
  }
})

// response middleware

app.use(function *(next){
  // yield control downstream
  yield next

  // sleep for 0-2s
  yield sleep(Math.random() * 2000 | 0)

  // error
  if (Math.random() > .75) {
    var err = new Error('boom')
    err.status = 500
    throw err
  }

  // random body
  var body = Array(Math.random() * 5 * 1024 | 9).join('a')
  this.status = 200
  this.body = body
});

var port = process.env.PORT || 3000
app.listen(port)
console.log('listening on port ' + port)

// sleep helper
function sleep(ms) {
  return function(done){
    setTimeout(done, ms)
  }
}