set host header if provided

pkg/clients/http/http.go

@@ -68,6 +68,11 @@ func (h *HTTPImpl) HealthCheckHTTP(address, method string, headers map[string][]
 
 		rq.Header = headers
 
+		hosts, ok := headers["Host"]
+		if ok && len(hosts) > 0 {
+			rq.Host = hosts[0]
+		}
+
 		if len(codes) == 0 {
 			codes = []int{200}
 		}

pkg/clients/http/http_test.go

@@ -3,6 +3,7 @@ package http
 import (
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"testing"
 	"time"
 
@@ -66,3 +67,41 @@ func TestHTTPHealthErrorsOnClientError(t *testing.T) {
 	assert.Error(t, err)
 	assert.Len(t, *reqs, 0)
 }
+
+func TestHTTPHealthSetsHostOnHostHeader(t *testing.T) {
+	url, reqs, cleanup := testSetupHTTPBasicServer(http.StatusOK, "")
+	defer cleanup()
+
+	c := NewHTTP(1*time.Millisecond, logger.NewTestLogger(t))
+
+	err := c.HealthCheckHTTP(url, "", map[string][]string{"Host": {"example.com"}}, "", []int{200}, 10*time.Millisecond)
+	assert.NoError(t, err)
+	assert.Len(t, *reqs, 1)
+	assert.Equal(t, "example.com", (*reqs)[0].Host)
+}
+
+func TestHTTPHealthSetsHostOnHostHeaderWithMultipleValues(t *testing.T) {
+	url, reqs, cleanup := testSetupHTTPBasicServer(http.StatusOK, "")
+	defer cleanup()
+
+	c := NewHTTP(1*time.Millisecond, logger.NewTestLogger(t))
+
+	err := c.HealthCheckHTTP(url, "", map[string][]string{"Host": {"example.com", "example.org"}}, "", []int{200}, 10*time.Millisecond)
+	assert.NoError(t, err)
+	assert.Len(t, *reqs, 1)
+	assert.Equal(t, "example.com", (*reqs)[0].Host)
+}
+
+func TestHTTPHealthSetsHostOnHostHeaderWithNoValues(t *testing.T) {
+	url, reqs, cleanup := testSetupHTTPBasicServer(http.StatusOK, "")
+	defer cleanup()
+
+	host := strings.TrimPrefix(url, "http://")
+
+	c := NewHTTP(1*time.Millisecond, logger.NewTestLogger(t))
+
+	err := c.HealthCheckHTTP(url, "", map[string][]string{}, "", []int{200}, 10*time.Millisecond)
+	assert.NoError(t, err)
+	assert.Len(t, *reqs, 1)
+	assert.Equal(t, host, (*reqs)[0].Host)
+}