Merge pull request #467 from eiszfuchs/feature/proxy-socket

proxy: Support unix sockets

middleware/proxy/proxy.go

@@ -63,7 +63,6 @@ var tryDuration = 60 * time.Second
 
 // ServeHTTP satisfies the middleware.Handler interface.
 func (p Proxy) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
-
 	for _, upstream := range p.Upstreams {
 		if middleware.Path(r.URL.Path).Matches(upstream.From()) && upstream.IsAllowedPath(r.URL.Path) {
 			var replacer middleware.Replacer

middleware/proxy/proxy_test.go

@@ -3,6 +3,7 @@ package proxy
 import (
 	"bufio"
 	"bytes"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"log"
@@ -13,7 +14,9 @@ import (
 	"os"
 	"strings"
 	"testing"
+	"runtime"
 	"time"
+	"path/filepath"
 
 	"golang.org/x/net/websocket"
 )
@@ -160,6 +163,69 @@ func TestWebSocketReverseProxyFromWSClient(t *testing.T) {
 	}
 }
 
+func TestUnixSocketProxy(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		return
+	}
+
+	trialMsg := "Is it working?"
+
+	var proxySuccess bool
+
+	// This is our fake "application" we want to proxy to
+	ts := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Request was proxied when this is called
+		proxySuccess = true
+
+		fmt.Fprint(w, trialMsg)
+	}))
+
+	// Get absolute path for unix: socket
+	socketPath, err := filepath.Abs("./test_socket")
+	if err != nil {
+		t.Fatalf("Unable to get absolute path: %v", err)
+	}
+
+	// Change httptest.Server listener to listen to unix: socket
+	ln, err := net.Listen("unix", socketPath)
+	if err != nil {
+		t.Fatalf("Unable to listen: %v", err)
+	}
+	ts.Listener = ln
+
+	ts.Start()
+	defer ts.Close()
+
+	url := strings.Replace(ts.URL, "http://", "unix:", 1)
+	p := newWebSocketTestProxy(url)
+
+	echoProxy := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		p.ServeHTTP(w, r)
+	}))
+	defer echoProxy.Close()
+
+	res, err := http.Get(echoProxy.URL)
+	if err != nil {
+		t.Fatalf("Unable to GET: %v", err)
+	}
+
+	greeting, err := ioutil.ReadAll(res.Body)
+	res.Body.Close()
+	if err != nil {
+		t.Fatalf("Unable to GET: %v", err)
+	}
+
+	actualMsg := fmt.Sprintf("%s", greeting)
+
+	if !proxySuccess {
+		t.Errorf("Expected request to be proxied, but it wasn't")
+	}
+
+	if actualMsg != trialMsg {
+		t.Errorf("Expected '%s' but got '%s' instead", trialMsg, actualMsg)
+	}
+}
+
 func newFakeUpstream(name string, insecure bool) *fakeUpstream {
 	uri, _ := url.Parse(name)
 	u := &fakeUpstream{

middleware/proxy/reverseproxy.go

@@ -59,6 +59,18 @@ func singleJoiningSlash(a, b string) string {
 	return a + b
 }
 
+// Though the relevant directive prefix is just "unix:", url.Parse
+// will - assuming the regular URL scheme - add additional slashes
+// as if "unix" was a request protocol.
+// What we need is just the path, so if "unix:/var/run/www.socket"
+// was the proxy directive, the parsed hostName would be
+// "unix:///var/run/www.socket", hence the ambiguous trimming.
+func socketDial(hostName string) func(network, addr string) (conn net.Conn, err error) {
+	return func(network, addr string) (conn net.Conn, err error) {
+		return net.Dial("unix", hostName[len("unix://"):])
+	}
+}
+
 // NewSingleHostReverseProxy returns a new ReverseProxy that rewrites
 // URLs to the scheme, host, and base path provided in target. If the
 // target's path is "/base" and the incoming request was for "/dir",
@@ -68,8 +80,15 @@ func singleJoiningSlash(a, b string) string {
 func NewSingleHostReverseProxy(target *url.URL, without string) *ReverseProxy {
 	targetQuery := target.RawQuery
 	director := func(req *http.Request) {
-		req.URL.Scheme = target.Scheme
-		req.URL.Host = target.Host
+		if target.Scheme == "unix" {
+			// to make Dial work with unix URL,
+			// scheme and host have to be faked
+			req.URL.Scheme = "http"
+			req.URL.Host = "socket"
+		} else {
+			req.URL.Scheme = target.Scheme
+			req.URL.Host = target.Host
+		}
 		req.URL.Path = singleJoiningSlash(target.Path, req.URL.Path)
 		if targetQuery == "" || req.URL.RawQuery == "" {
 			req.URL.RawQuery = targetQuery + req.URL.RawQuery
@@ -80,7 +99,13 @@ func NewSingleHostReverseProxy(target *url.URL, without string) *ReverseProxy {
 			req.URL.Path = strings.TrimPrefix(req.URL.Path, without)
 		}
 	}
-	return &ReverseProxy{Director: director}
+	rp := &ReverseProxy{Director: director}
+	if target.Scheme == "unix" {
+		rp.Transport = &http.Transport{
+			Dial: socketDial(target.String()),
+		}
+	}
+	return rp
 }
 
 func copyHeader(dst, src http.Header) {

middleware/proxy/upstream.go

@@ -65,7 +65,8 @@ func NewStaticUpstreams(c parse.Dispenser) ([]Upstream, error) {
 
 		upstream.Hosts = make([]*UpstreamHost, len(to))
 		for i, host := range to {
-			if !strings.HasPrefix(host, "http") {
+			if !strings.HasPrefix(host, "http") &&
+				!strings.HasPrefix(host, "unix:") {
 				host = "http://" + host
 			}
 			uh := &UpstreamHost{