hydrapost.go

package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"sync"
)

var (
	upstreamURLs = []string{
		"https://ya.ru",
		"https://google.com",
		"https://bing.com",
	}
)

func main() {
	http.HandleFunc("/", forwardHandler)
	log.Println("Server started on port 8080")
	log.Fatal(http.ListenAndServe(":8080", nil))
}

func forwardHandler(w http.ResponseWriter, req *http.Request) {
	// Create a WaitGroup to wait for all goroutines to finish
	var wg sync.WaitGroup

	responses := make(chan string, len(upstreamURLs))

	for _, upstream := range upstreamURLs {
		wg.Add(1)
		go func(upstream string) {
			defer wg.Done()
			forwardRequest(upstream, req, responses)
		}(upstream)
	}

	go func() {
		wg.Wait()
		close(responses)
	}()

	for response := range responses {
		fmt.Fprintln(w, response)
	}
}

func forwardRequest(upstream string, req *http.Request, responses chan<- string) {
	request, err := http.NewRequest(req.Method, upstream, req.Body)
	if err != nil {
		log.Printf("Error creating request for upstream %s: %v", upstream, err)
		responses <- fmt.Sprintf("Error contacting upstream %s", upstream)
		return
	}
	request.Header = req.Header

	client := &http.Client{}
	resp, err := client.Do(request)
	if err != nil {
		log.Printf("Error forwarding request to upstream %s: %v", upstream, err)
		responses <- fmt.Sprintf("Error contacting upstream %s", upstream)
		return
	}
	defer resp.Body.Close()

	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		log.Printf("Error reading response from upstream %s: %v", upstream, err)
		responses <- fmt.Sprintf("Error reading response from upstream %s", upstream)
		return
	}

	responses <- string(body)
}