middleware/proxy: fix race; add Go 1.7 backward compatibility (#603)

* Fix race on backend health status update
* Ensure test case is compatible on Go 1.7

middleware/proxy/proxy.go

@@ -3,6 +3,7 @@ package proxy
 
 import (
 	"errors"
+	"sync"
 	"sync/atomic"
 	"time"
 
@@ -59,6 +60,7 @@ type UpstreamHost struct {
 	Unhealthy         bool
 	CheckDown         UpstreamHostDownFunc
 	WithoutPathPrefix string
+	checkMu           sync.Mutex
 }
 
 // Down checks whether the upstream host is down or not.

middleware/proxy/upstream.go

@@ -250,7 +250,9 @@ func (u *staticUpstream) healthCheck() {
 		}
 
 		hostURL := "http://" + net.JoinHostPort(checkHostName, checkPort) + u.HealthCheck.Path
-		host.Unhealthy = false
+
+		host.checkMu.Lock()
+		defer host.checkMu.Unlock()
 
 		if r, err := http.Get(hostURL); err == nil {
 			io.Copy(ioutil.Discard, r.Body)
@@ -259,6 +261,8 @@ func (u *staticUpstream) healthCheck() {
 				log.Printf("[WARNING] Health check URL %s returned HTTP code %d\n",
 					hostURL, r.StatusCode)
 				host.Unhealthy = true
+			} else {
+				host.Unhealthy = false
 			}
 		} else {
 			log.Printf("[WARNING] Health check probe failed: %v\n", err)

test/proxy_http_health_test.go

@@ -4,6 +4,7 @@ import (
 	"io"
 	"io/ioutil"
 	"log"
+	"net"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -29,7 +30,11 @@ func TestProxyWithHTTPCheckOK(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	healthCheckPort := healthCheckURL.Port()
+	// TODO: use URL.Port() (Go 1.8+) once we've deprecated Go 1.7 support
+	var healthCheckPort string
+	if _, healthCheckPort, err = net.SplitHostPort(healthCheckURL.Host); err != nil {
+		healthCheckPort = "80"
+	}
 
 	name, rm, err := test.TempFile(".", exampleOrg)
 	if err != nil {