Setting Hostname from Pods on EndpointSlice to match Endpoints behavior.

This was an oversight in the initial EndpointSlice release. This update
will ensure that Endpoints and EndpointSlices use the same logic to set
the Hostname attribute.

pkg/controller/util/endpoint/controller_utils.go

@@ -143,6 +143,12 @@ func ShouldPodBeInEndpoints(pod *v1.Pod) bool {
 	return true
 }
 
+// ShouldSetHostname returns true if the Hostname attribute should be set on an
+// Endpoints Address or EndpointSlice Endpoint.
+func ShouldSetHostname(pod *v1.Pod, svc *v1.Service) bool {
+	return len(pod.Spec.Hostname) > 0 && pod.Spec.Subdomain == svc.Name && svc.Namespace == pod.Namespace
+}
+
 // PodChanged returns two boolean values, the first returns true if the pod.
 // has changed, the second value returns true if the pod labels have changed.
 func PodChanged(oldPod, newPod *v1.Pod, endpointChanged EndpointsMatch) (bool, bool) {

pkg/controller/util/endpoint/controller_utils_test.go

@@ -81,16 +81,19 @@ func TestDetermineNeededServiceUpdates(t *testing.T) {
 			union: sets.NewString(),
 		},
 	}
-	for _, testCase := range testCases {
-		retval := determineNeededServiceUpdates(testCase.a, testCase.b, false)
-		if !retval.Equal(testCase.xor) {
-			t.Errorf("%s (with podChanged=false): expected: %v  got: %v", testCase.name, testCase.xor.List(), retval.List())
-		}
 
-		retval = determineNeededServiceUpdates(testCase.a, testCase.b, true)
-		if !retval.Equal(testCase.union) {
-			t.Errorf("%s (with podChanged=true): expected: %v  got: %v", testCase.name, testCase.union.List(), retval.List())
-		}
+	for _, testCase := range testCases {
+		t.Run(testCase.name, func(t *testing.T) {
+			retval := determineNeededServiceUpdates(testCase.a, testCase.b, false)
+			if !retval.Equal(testCase.xor) {
+				t.Errorf("%s (with podChanged=false): expected: %v  got: %v", testCase.name, testCase.xor.List(), retval.List())
+			}
+
+			retval = determineNeededServiceUpdates(testCase.a, testCase.b, true)
+			if !retval.Equal(testCase.union) {
+				t.Errorf("%s (with podChanged=true): expected: %v  got: %v", testCase.name, testCase.union.List(), retval.List())
+			}
+		})
 	}
 }
 
@@ -224,11 +227,73 @@ func TestShouldPodBeInEndpoints(t *testing.T) {
 			expected: true,
 		},
 	}
+
 	for _, test := range testCases {
-		result := ShouldPodBeInEndpoints(test.pod)
-		if result != test.expected {
-			t.Errorf("%s: expected : %t, got: %t", test.name, test.expected, result)
-		}
+		t.Run(test.name, func(t *testing.T) {
+			result := ShouldPodBeInEndpoints(test.pod)
+			if result != test.expected {
+				t.Errorf("expected: %t, got: %t", test.expected, result)
+			}
+		})
+	}
+}
+
+func TestShouldSetHostname(t *testing.T) {
+	testCases := map[string]struct {
+		pod      *v1.Pod
+		service  *v1.Service
+		expected bool
+	}{
+		"all matching": {
+			pod:      genSimplePod("ns", "foo", "svc-name"),
+			service:  genSimpleSvc("ns", "svc-name"),
+			expected: true,
+		},
+		"all matching, hostname not set": {
+			pod:      genSimplePod("ns", "", "svc-name"),
+			service:  genSimpleSvc("ns", "svc-name"),
+			expected: false,
+		},
+		"all set, different name/subdomain": {
+			pod:      genSimplePod("ns", "hostname", "subdomain"),
+			service:  genSimpleSvc("ns", "name"),
+			expected: false,
+		},
+		"all set, different namespace": {
+			pod:      genSimplePod("ns1", "hostname", "svc-name"),
+			service:  genSimpleSvc("ns2", "svc-name"),
+			expected: false,
+		},
+	}
+
+	for name, testCase := range testCases {
+		t.Run(name, func(t *testing.T) {
+			result := ShouldSetHostname(testCase.pod, testCase.service)
+			if result != testCase.expected {
+				t.Errorf("expected: %t, got: %t", testCase.expected, result)
+			}
+		})
+	}
+}
+
+func genSimplePod(namespace, hostname, subdomain string) *v1.Pod {
+	return &v1.Pod{
+		ObjectMeta: metav1.ObjectMeta{
+			Namespace: namespace,
+		},
+		Spec: v1.PodSpec{
+			Hostname:  hostname,
+			Subdomain: subdomain,
+		},
+	}
+}
+
+func genSimpleSvc(namespace, name string) *v1.Service {
+	return &v1.Service{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      name,
+			Namespace: namespace,
+		},
 	}
 }