Add util functions for backendConfig annotation

pkg/annotations/service.go

@@ -40,6 +40,15 @@ const (
 	// 3. Adding this annotation on ingress.
 	NetworkEndpointGroupAlphaAnnotation = "alpha.cloud.google.com/load-balancer-neg"
 
+	// BackendConfigKey is a stringified JSON with two fields:
+	// - "ports": a map of port names or port numbers to backendConfig names
+	// - "default": denotes the default backendConfig name for all ports except
+	// those are explicitly referenced.
+	// Examples:
+	// - '{"ports":{"my-https-port":"config-https","my-http-port":"config-http"}}'
+	// - '{"default":"config-default","ports":{"my-https-port":"config-https"}}'
+	BackendConfigKey = "alpha.cloud.google.com/backend-config"
+
 	// ProtocolHTTP protocol for a service
 	ProtocolHTTP AppProtocol = "HTTP"
 	// ProtocolHTTPS protocol for a service
@@ -93,3 +102,25 @@ func (svc Service) NEGEnabled() bool {
 	v, ok := svc.v[NetworkEndpointGroupAlphaAnnotation]
 	return ok && v == "true"
 }
+
+type BackendConfigs struct {
+	Default string            `json:"default,omitempty"`
+	Ports   map[string]string `json:"ports,omitempty"`
+}
+
+// GetBackendConfigs returns BackendConfigs for the service.
+func (svc Service) GetBackendConfigs() (*BackendConfigs, error) {
+	val, ok := svc.v[BackendConfigKey]
+	if !ok {
+		return nil, nil
+	}
+
+	configs := BackendConfigs{}
+	if err := json.Unmarshal([]byte(val), &configs); err != nil {
+		return nil, err
+	}
+	if configs.Default == "" && len(configs.Ports) == 0 {
+		return nil, fmt.Errorf("no backendConfigs found in annotation: %v", val)
+	}
+	return &configs, nil
+}

pkg/annotations/service_test.go

@@ -118,3 +118,100 @@ func TestService(t *testing.T) {
 		}
 	}
 }
+
+func TestBackendConfigs(t *testing.T) {
+	testcases := []struct {
+		desc            string
+		svc             *v1.Service
+		expectedConfigs *BackendConfigs
+		expectErr       bool
+	}{
+		{
+			desc: "no backendConfig annotation",
+			svc:  &v1.Service{},
+		},
+		{
+			desc: "single backendConfig",
+			svc: &v1.Service{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{
+						BackendConfigKey: `{"ports":{"http": "config-http"}}`,
+					},
+				},
+			},
+			expectedConfigs: &BackendConfigs{
+				Ports: map[string]string{
+					"http": "config-http",
+				},
+			},
+		},
+		{
+			desc: "multiple backendConfigs",
+			svc: &v1.Service{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{
+						BackendConfigKey: `{"ports":{"http": "config-http", "https": "config-https"}}`,
+					},
+				},
+			},
+			expectedConfigs: &BackendConfigs{
+				Ports: map[string]string{
+					"http":  "config-http",
+					"https": "config-https",
+				},
+			},
+		}, {
+			desc: "multiple backendConfigs with default",
+			svc: &v1.Service{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{
+						BackendConfigKey: `{"default": "config-default", "ports":{"http": "config-http", "https": "config-https"}}`,
+					},
+				},
+			},
+			expectedConfigs: &BackendConfigs{
+				Default: "config-default",
+				Ports: map[string]string{
+					"http":  "config-http",
+					"https": "config-https",
+				},
+			},
+		},
+		{
+			desc: "invalid backendConfig annotation",
+			svc: &v1.Service{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{
+						BackendConfigKey: `invalid`,
+					},
+				},
+			},
+			expectErr: true,
+		},
+		{
+			desc: "wrong field name in backendConfig annotation",
+			svc: &v1.Service{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{
+						BackendConfigKey: `{"portstypo":{"https": "config-https"}}`,
+					},
+				},
+			},
+			expectErr: true,
+		},
+	}
+
+	for _, tc := range testcases {
+		svc := FromService(tc.svc)
+		configs, err := svc.GetBackendConfigs()
+		if tc.expectErr {
+			if err == nil {
+				t.Errorf("%s: for annotions %+v; svc.GetBackendConfigs() = %v, _; want _, error", tc.desc, svc.v, configs)
+			}
+			continue
+		}
+		if err != nil || !reflect.DeepEqual(configs, tc.expectedConfigs) {
+			t.Errorf("%s: for annotions %+v; svc.GetBackendConfigs() = %v, %v; want %v, nil", tc.desc, svc.v, configs, err, tc.expectedConfigs)
+		}
+	}
+}