Light wrapper for the Go http client adding (essential) timeouts for both connect and readwrite.

httpclient.go

package httpclient

import (
    "net"
    "net/http"
    "time"
)

type Config struct {
    ConnectTimeout   time.Duration
    ReadWriteTimeout time.Duration
}

func TimeoutDialer(config *Config) func(net, addr string) (c net.Conn, err error) {
    return func(netw, addr string) (net.Conn, error) {
        conn, err := net.DialTimeout(netw, addr, config.ConnectTimeout)
        if err != nil {
            return nil, err
	    }
        conn.SetDeadline(time.Now().Add(config.ReadWriteTimeout))
        return conn, nil
    }
}

func NewTimeoutClient(args ...interface{}) *http.Client {
    // Default configuration
    config := &Config{
        ConnectTimeout:   1 * time.Second,
        ReadWriteTimeout: 1 * time.Second,
    }

    // merge the default with user input if there is one
    if len(args) == 1 {
        timeout := args[0].(time.Duration)
        config.ConnectTimeout = timeout
        config.ReadWriteTimeout = timeout
    }

    if len(args) == 2 {
        config.ConnectTimeout = args[0].(time.Duration)
        config.ReadWriteTimeout = args[1].(time.Duration)
    }

    return &http.Client{
        Transport: &http.Transport{
            Dial: TimeoutDialer(config),
        },
    }
}

httpclient_test.go

package httpclient

import (
	"io"
	"net"
	"net/http"
	"sync"
	"testing"
	"time"
)

var starter sync.Once
var addr net.Addr

func testHandler(w http.ResponseWriter, req *http.Request) {
	time.Sleep(500 * time.Millisecond)
	io.WriteString(w, "hello, world!\n")
}

func testDelayedHandler(w http.ResponseWriter, req *http.Request) {
	time.Sleep(2100 * time.Millisecond)
	io.WriteString(w, "hello, world ... in a bit\n")
}

func setupMockServer(t *testing.T) {
	http.HandleFunc("/test", testHandler)
	http.HandleFunc("/test-delayed", testDelayedHandler)
	ln, err := net.Listen("tcp", ":0")
	if err != nil {
		t.Fatalf("failed to listen - %s", err.Error())
	}
	go func() {
		err = http.Serve(ln, nil)
		if err != nil {
			t.Fatalf("failed to start HTTP server - %s", err.Error())
		}
	}()
	addr = ln.Addr()
}

func TestDefaultConfig(t *testing.T) {
	starter.Do(func() { setupMockServer(t) })

	httpClient := NewTimeoutClient()
	req, _ := http.NewRequest("GET", "http://"+addr.String()+"/test-delayed", nil)

	httpClient = NewTimeoutClient()

	_, err := httpClient.Do(req)
	if err == nil {
		t.Fatalf("request should have timed out")
	}

}

func TestHttpClient(t *testing.T) {
	starter.Do(func() { setupMockServer(t) })

	httpClient := NewTimeoutClient()

	req, _ := http.NewRequest("GET", "http://"+addr.String()+"/test", nil)

	resp, err := httpClient.Do(req)
	if err != nil {
		t.Fatalf("1st request failed - %s", err.Error())
	}
	defer resp.Body.Close()

	connectTimeout := (250 * time.Millisecond)
	readWriteTimeout := (50 * time.Millisecond)

	httpClient = NewTimeoutClient(connectTimeout, readWriteTimeout)

	resp, err = httpClient.Do(req)
	if err == nil {
		t.Fatalf("2nd request should have timed out")
	}

	resp, err = httpClient.Do(req)
	if resp != nil {
		t.Fatalf("3nd request should not have timed out")
	}

}

httpclient_usage.go

/*
    This wrapper takes care of both the connection timeout and the readwrite timeout.
    WARNING: You must instantiate this every time you want to use it, otherwise it is 
    likely that the timeout is reached before you actually make the call.

    One argument sets the connect timeout and the readwrite timeout to the same value.
    Other wise, 2 arguments are 1) connect and 2) readwrite

    It returns an *http.Client
*/

package main

import(
    "httpclient"
    "time"
)

func main() {
    httpClient := httpclient.NewWithTimeout(500*time.Millisecond, 1*time.Second)
    resp, err := httpClient.Get("http://google.com")
    if err != nil {
        fmt.Println("Rats! Google is down.")
    }
}

Hi, thank you for you code.

But I found a little problem when use this set timeout logic with keep-alive connection.

Because the http package reuse the backend TCP/IP connection, when the http connection is keep-alive.

So, when a connection reused after a few seconds. http.Get() will returns a timeout error.

This is my solution: a TimeoutConn from Dial callback.

https://gist.github.com/idada/9144886

http://golang.org/pkg/net/http/httptest/ is dope y'all

Hey, check out my fork: http://gist.github.com/seantalts/11266762

The method here doesn't work with keepalive (you get random timeouts during regular, working requests) and @idada 's method has nondeterministic timeouts and lets idle connections timeout, but mine addresses both of those issues in kind of a basic way I think. Updated tests to use httptest and test that keepalive connections are kept alive as well as that timeouts are working properly.

Thanks guys for the comments and the extensions. @seantalts thanks for the reference to httptest (duh). I'm back in Go-land and will give your client a try for a project I am working on.

Wow! httptest IS dope. Good find thanks for pointing it out and thanks for all your Gists guys!

TimeoutDialer have problem in go.1.16 ;
it will cause i/o timeout , in a short duration , like 50 ms , but we set it more than 1 second.

because the code not using keepAlive and golang will using conn cache pool for sites.

so we should use http.Client{ Timeout: XXX , ... } to set one request timeout .
not this!!!!!!!!