main.go

package main

import (
  "bootic_pageviews/request"
  "bootic_pageviews/udp"
  "flag"
  "github.com/gorilla/mux"
  "io/ioutil"
  "log"
  "net/http"
  "net/url"
  "strconv"
)

func PageviewsHandler(gif_path string, publisher *udp.Publisher) (handle func(http.ResponseWriter, *http.Request)) {

  // cache the file once
  gif, _ := ioutil.ReadFile(gif_path)

  // return closure with access to gif image
  return func(res http.ResponseWriter, req *http.Request) {
    res.Header().Add("Content-Type", "image/gif")
    res.Header().Add("Cache-Control", "no-store, no-cache, must-revalidate, private, proxy-revalidate")
    res.Header().Add("Pragma", "no-cache")
    res.Header().Add("Expires", "Fri, 24 Nov 2000 01:00:00 GMT")

    // Content-Length. This is not a streaming connection.
    res.Header().Add("Content-Length", strconv.Itoa(len(gif)))
    res.Write(gif)

    // Get request data for async processing
    params := mux.Vars(req)
    userAgent := req.UserAgent()
    params["ua"] = userAgent
    query, _ := url.ParseQuery(req.URL.RawQuery)
    // async send data to events collector
    go request.ProcessAndSend(params, query, publisher)
  }

}

func main() {

  var (
    udp_host  string
    http_host string
    gif_path  string
  )

  flag.StringVar(&udp_host, "udphost", "localhost:5555", "UDP host:port to send packets to")
  flag.StringVar(&http_host, "httphost", "localhost:8080", "HTTP host:port to serve tracking gif")
  flag.StringVar(&gif_path, "gifpath", "", "Absolute path to 1x1px tracking gif")

  flag.Parse()

  // UDP client publishes events over UDP
  pub := udp.NewPublisher(udp_host)

  // HTTP router
  router := mux.NewRouter()

  // Bind an HTTP request handler that publishes parsed GET requests to UDP publishers
  router.HandleFunc("/r/{app_name}/{account_name}/{type}", PageviewsHandler(gif_path, pub)).Methods("GET")

  http.Handle("/", router)
  log.Println("Starting HTTP endpoint at", http_host)
  log.Fatal(http.ListenAndServe(http_host, nil))
}