Allow overriding port for backend healthchecks

healthcheck/healthcheck.go

@@ -3,8 +3,10 @@ package healthcheck
 import (
 	"context"
 	"fmt"
+	"net"
 	"net/http"
 	"net/url"
+	"strconv"
 	"sync"
 	"time"
 
@@ -27,6 +29,7 @@ func GetHealthCheck() *HealthCheck {
 // Options are the public health check options.
 type Options struct {
 	Path     string
+	Port     int
 	Interval time.Duration
 	LB       LoadBalancer
 }
@@ -127,11 +130,32 @@ func checkBackend(currentBackend *BackendHealthCheck) {
 	}
 }
 
+func (backend *BackendHealthCheck) newRequest(serverURL *url.URL) (*http.Request, error) {
+	if backend.Options.Port == 0 {
+		return http.NewRequest("GET", serverURL.String()+backend.Path, nil)
+	}
+
+	// copy the url and add the port to the host
+	u := &url.URL{}
+	*u = *serverURL
+	u.Host = net.JoinHostPort(u.Hostname(), strconv.Itoa(backend.Options.Port))
+	u.Path = u.Path + backend.Path
+
+	return http.NewRequest("GET", u.String(), nil)
+}
+
 func checkHealth(serverURL *url.URL, backend *BackendHealthCheck) bool {
 	client := http.Client{
 		Timeout: backend.requestTimeout,
 	}
-	resp, err := client.Get(serverURL.String() + backend.Path)
+	req, err := backend.newRequest(serverURL)
+	if err != nil {
+		log.Errorf("Failed to create HTTP request [%s] for healthcheck: %s", serverURL, err)
+		return false
+	}
+
+	resp, err := client.Do(req)
+
 	if err == nil {
 		defer resp.Body.Close()
 	}

healthcheck/healthcheck_test.go

@@ -193,6 +193,73 @@ func TestSetBackendsConfiguration(t *testing.T) {
 	}
 }
 
+func TestNewRequest(t *testing.T) {
+	tests := []struct {
+		desc     string
+		host     string
+		port     int
+		path     string
+		expected string
+	}{
+		{
+			desc:     "no port override",
+			host:     "backend1:80",
+			port:     0,
+			path:     "/test",
+			expected: "http://backend1:80/test",
+		},
+		{
+			desc:     "port override",
+			host:     "backend2:80",
+			port:     8080,
+			path:     "/test",
+			expected: "http://backend2:8080/test",
+		},
+		{
+			desc:     "no port override with no port in host",
+			host:     "backend1",
+			port:     0,
+			path:     "/health",
+			expected: "http://backend1/health",
+		},
+		{
+			desc:     "port override with no port in host",
+			host:     "backend2",
+			port:     8080,
+			path:     "/health",
+			expected: "http://backend2:8080/health",
+		},
+	}
+
+	for _, test := range tests {
+		test := test
+		t.Run(test.desc, func(t *testing.T) {
+			t.Parallel()
+			backend := NewBackendHealthCheck(
+				Options{
+					Path: test.path,
+					Port: test.port,
+				})
+
+			u := &url.URL{
+				Scheme: "http",
+				Host:   test.host,
+			}
+
+			req, err := backend.newRequest(u)
+			if err != nil {
+				t.Fatalf("failed to create new backend request: %s", err)
+			}
+
+			actual := req.URL.String()
+			if actual != test.expected {
+				t.Fatalf("got %s for healthcheck URL, wanted %s", actual, test.expected)
+			}
+		})
+	}
+
+}
+
 func MustParseURL(rawurl string) *url.URL {
 	u, err := url.Parse(rawurl)
 	if err != nil {