urlfetch context.WithTimeout

main.go

package main

import (
	"context"
	"fmt"
	"net/http"
	"time"

	"google.golang.org/appengine"
	"google.golang.org/appengine/urlfetch"
)

func init() {
	http.HandleFunc("/hello", handler)
}

func handler(w http.ResponseWriter, r *http.Request) {
	ctx := appengine.NewContext(r)

	status, err := getHoge(ctx)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	fmt.Fprintf(w, "%s", status)
}

func getHoge(ctx context.Context) (string, error) {
	cctx, cancel := context.WithTimeout(ctx, 30*time.Second)
	defer cancel()

	uf := urlfetch.Client(cctx)
	req, err := http.NewRequest(http.MethodGet, "https://google.com", nil)
	if err != nil {
		return "", err
	}
	res, err := uf.Do(req)
	if err != nil {
		return "", err
	}
	return res.Status, nil
}