GCE: Add annotations and helper functions for network tiers

These functions will be consumed in the follow-up changes.

pkg/cloudprovider/providers/gce/gce_annotations.go

@@ -17,11 +17,16 @@ limitations under the License.
 package gce
 
 import (
+	"fmt"
+	"strings"
+
 	"github.com/golang/glog"
+
 	"k8s.io/api/core/v1"
 )
 
 type LoadBalancerType string
+type NetworkTier string
 
 const (
 	// ServiceAnnotationLoadBalancerType is annotated on a service with type LoadBalancer
@@ -39,6 +44,17 @@ const (
 	ServiceAnnotationILBBackendShare = "alpha.cloud.google.com/load-balancer-backend-share"
 	// This annotation did not correctly specify "alpha", so both annotations will be checked.
 	deprecatedServiceAnnotationILBBackendShare = "cloud.google.com/load-balancer-backend-share"
+
+	// NetworkTierAnnotationKey is annotated on a Service object to indicate which
+	// network tier a GCP LB should use. The valid values are "Standard" and
+	// "Premium" (default).
+	NetworkTierAnnotationKey      = "cloud.google.com/network-tier"
+	NetworkTierAnnotationStandard = "Standard"
+	NetworkTierAnnotationPremium  = "Premium"
+
+	NetworkTierStandard NetworkTier = NetworkTierAnnotationStandard
+	NetworkTierPremium  NetworkTier = NetworkTierAnnotationPremium
+	NetworkTierDefault  NetworkTier = NetworkTierPremium
 )
 
 // GetLoadBalancerAnnotationType returns the type of GCP load balancer which should be assembled.
@@ -77,3 +93,42 @@ func GetLoadBalancerAnnotationBackendShare(service *v1.Service) bool {
 
 	return false
 }
+
+// GetServiceNetworkTier returns the network tier of GCP load balancer
+// which should be assembled, and an error if the specified tier is not
+// supported.
+func GetServiceNetworkTier(service *v1.Service) (NetworkTier, error) {
+	l, ok := service.Annotations[NetworkTierAnnotationKey]
+	if !ok {
+		return NetworkTierDefault, nil
+	}
+
+	v := NetworkTier(l)
+	switch v {
+	case NetworkTierStandard:
+		fallthrough
+	case NetworkTierPremium:
+		return v, nil
+	default:
+		return NetworkTierDefault, fmt.Errorf("unsupported network tier: %q", v)
+	}
+}
+
+// ToGCEValue converts NetworkTier to a string that we can populate the
+// NetworkTier field of GCE objects.
+func (n NetworkTier) ToGCEValue() string {
+	return strings.ToUpper(string(n))
+}
+
+// NetworkTierGCEValueToType converts the value of the NetworkTier field of a
+// GCE object to the NetworkTier type.
+func NetworkTierGCEValueToType(s string) NetworkTier {
+	switch s {
+	case "STANDARD":
+		return NetworkTierStandard
+	case "PREMIUM":
+		return NetworkTierPremium
+	default:
+		return NetworkTier(s)
+	}
+}

pkg/cloudprovider/providers/gce/gce_annotations_test.go

@@ -0,0 +1,70 @@
+/*
+Copyright 2017 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 gce
+
+import (
+	"testing"
+
+	"k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestServiceNetworkTierAnnotationKey(t *testing.T) {
+	createTestService := func() *v1.Service {
+		return &v1.Service{
+			ObjectMeta: metav1.ObjectMeta{
+				UID:       "randome-uid",
+				Name:      "test-svc",
+				Namespace: "test-ns",
+			},
+		}
+	}
+
+	for testName, testCase := range map[string]struct {
+		annotations  map[string]string
+		expectedTier NetworkTier
+		expectErr    bool
+	}{
+		"Use the default when the annotation does not exist": {
+			annotations:  nil,
+			expectedTier: NetworkTierDefault,
+		},
+		"Standard tier": {
+			annotations:  map[string]string{NetworkTierAnnotationKey: "Standard"},
+			expectedTier: NetworkTierStandard,
+		},
+		"Premium tier": {
+			annotations:  map[string]string{NetworkTierAnnotationKey: "Premium"},
+			expectedTier: NetworkTierPremium,
+		},
+		"Report an error on invalid network tier value": {
+			annotations:  map[string]string{NetworkTierAnnotationKey: "Unknown-tier"},
+			expectedTier: NetworkTierPremium,
+			expectErr:    true,
+		},
+	} {
+		t.Run(testName, func(t *testing.T) {
+			svc := createTestService()
+			svc.Annotations = testCase.annotations
+			actualTier, err := GetServiceNetworkTier(svc)
+			assert.Equal(t, testCase.expectedTier, actualTier)
+			assert.Equal(t, testCase.expectErr, err != nil)
+		})
+	}
+}