x.go

package main

import (
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"os"
	"strconv"
	"strings"
)

var (
	respReader infiniteReader
)

type infiniteReader []byte

func (r infiniteReader) Read(p []byte) (int, error) {
	return copy(p, r), nil
}

func dynamicHandler(w http.ResponseWriter, r *http.Request) {
	io.Copy(ioutil.Discard, r.Body)

	q := r.URL.Query()

	var bodySize int64

	if v := q.Get("bodySize"); v != "" {
		if i, err := strconv.ParseInt(v, 0, 64); err == nil {
			bodySize = i
		}
	}

	io.CopyN(w, respReader, bodySize)
}

func staticHandler(w http.ResponseWriter, r *http.Request) {
	io.Copy(ioutil.Discard, r.Body)
	fmt.Fprintf(w, "HI")
}

func main() {
	respReader = infiniteReader(strings.Repeat("a", 1024))

	port := os.Getenv("PORT")
	if port == "" {
		port = "12345"
	}

	http.HandleFunc("/dynamic", dynamicHandler)
	http.HandleFunc("/", staticHandler)
	http.ListenAndServe(":"+port, nil)
}