Add Custom Response Header Logic and the Unit Tests for it

pkg/backends/features/customresponseheaders.go

@@ -0,0 +1,47 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+package features
+
+import (
+	"reflect"
+
+	"k8s.io/ingress-gce/pkg/composite"
+	"k8s.io/ingress-gce/pkg/utils"
+	"k8s.io/klog/v2"
+)
+
+// EnsureCustomResponseHeaders reads the CustomResponseHeaders configuration specified in the ServicePort.BackendConfig
+// and applies it to the BackendService. It returns true if there was a difference between
+// current settings on the BackendService and ServicePort.BackendConfig.
+
+func EnsureCustomResponseHeaders(sp utils.ServicePort, be *composite.BackendService) bool {
+	desiredHeaders := []string{}
+	if sp.BackendConfig.Spec.CustomResponseHeaders != nil {
+		desiredHeaders = sp.BackendConfig.Spec.CustomResponseHeaders.Headers
+	}
+	currentHeaders := []string{}
+	if be.CustomResponseHeaders != nil {
+		currentHeaders = be.CustomResponseHeaders
+	}
+
+	if !reflect.DeepEqual(desiredHeaders, currentHeaders) {
+		be.CustomResponseHeaders = desiredHeaders
+		klog.V(2).Infof("Updated Custom Response Headers for service %v/%v.", sp.ID.Service.Namespace, sp.ID.Service.Name)
+		return true
+	}
+
+	return false
+}

pkg/backends/features/customresponseheaders_test.go

@@ -0,0 +1,99 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package features
+
+import (
+	"testing"
+
+	backendconfigv1 "k8s.io/ingress-gce/pkg/apis/backendconfig/v1"
+	"k8s.io/ingress-gce/pkg/composite"
+	"k8s.io/ingress-gce/pkg/utils"
+)
+
+var testCustomResponseHeader = []string{"X-TEST-HEADER:{test-value}"}
+
+func TestEnsureCustomResponseHeaders(t *testing.T) {
+	testCases := []struct {
+		desc           string
+		sp             utils.ServicePort
+		be             *composite.BackendService
+		updateExpected bool
+	}{
+		{
+			desc:           "Custom Response Headers missing from both ends, no update needed",
+			sp:             utils.ServicePort{BackendConfig: &backendconfigv1.BackendConfig{}},
+			be:             &composite.BackendService{},
+			updateExpected: false,
+		},
+		{
+			desc: "No header in current setting, new headers in backendConfig, update needed",
+			sp: utils.ServicePort{BackendConfig: &backendconfigv1.BackendConfig{
+				Spec: backendconfigv1.BackendConfigSpec{
+					CustomResponseHeaders: &backendconfigv1.CustomResponseHeadersConfig{
+						Headers: testCustomResponseHeader,
+					},
+				},
+			}},
+			be:             &composite.BackendService{},
+			updateExpected: true,
+		},
+		{
+			desc: "Having headers in current setting, no header in backendConfig, update needed",
+			sp:   utils.ServicePort{BackendConfig: &backendconfigv1.BackendConfig{}},
+			be: &composite.BackendService{
+				CustomResponseHeaders: testCustomResponseHeader,
+			},
+			updateExpected: true,
+		},
+		{
+			desc: "Having headers in current setting, new headers in backendConfig, update needed",
+			sp: utils.ServicePort{BackendConfig: &backendconfigv1.BackendConfig{
+				Spec: backendconfigv1.BackendConfigSpec{
+					CustomResponseHeaders: &backendconfigv1.CustomResponseHeadersConfig{
+						Headers: append(testCustomResponseHeader, "X-TEST-HEADER2:{test-value2}"),
+					},
+				},
+			}},
+			be: &composite.BackendService{
+				CustomResponseHeaders: testCustomResponseHeader,
+			},
+			updateExpected: true,
+		},
+		{
+			desc: "Identical headers, no update",
+			sp: utils.ServicePort{BackendConfig: &backendconfigv1.BackendConfig{
+				Spec: backendconfigv1.BackendConfigSpec{
+					CustomResponseHeaders: &backendconfigv1.CustomResponseHeadersConfig{
+						Headers: testCustomResponseHeader,
+					},
+				},
+			}},
+			be: &composite.BackendService{
+				CustomResponseHeaders: testCustomResponseHeader,
+			},
+			updateExpected: false,
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			result := EnsureCustomResponseHeaders(tc.sp, tc.be)
+			if result != tc.updateExpected {
+				t.Errorf("Expected %v but got %v", tc.updateExpected, result)
+			}
+		})
+	}
+}

pkg/backends/syncer.go

@@ -108,6 +108,7 @@ func (s *backendSyncer) ensureBackendService(sp utils.ServicePort) error {
 		needUpdate = features.EnsureDraining(sp, be) || needUpdate
 		needUpdate = features.EnsureAffinity(sp, be) || needUpdate
 		needUpdate = features.EnsureCustomRequestHeaders(sp, be) || needUpdate
+		needUpdate = features.EnsureCustomResponseHeaders(sp, be) || needUpdate
 		needUpdate = features.EnsureLogging(sp, be) || needUpdate
 	}