Add support for Server Alias in Nginx

Adds support for server alias in nginx. Adds a new annotation
which allows us to specify a server alias that will be appended
to the server name.

core/pkg/ingress/annotations/alias/main.go

@@ -0,0 +1,42 @@
+/*
+Copyright 2016 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 alias
+
+import (
+	extensions "k8s.io/api/extensions/v1beta1"
+
+	"k8s.io/ingress/core/pkg/ingress/annotations/parser"
+)
+
+const (
+	annotation = "ingress.kubernetes.io/server-alias"
+)
+
+type alias struct {
+}
+
+// NewParser creates a new CORS annotation parser
+func NewParser() parser.IngressAnnotation {
+	return alias{}
+}
+
+// Parse parses the annotations contained in the ingress rule
+// used to indicate if the location/s contains a fragment of
+// configuration to be included inside the paths of the rules
+func (a alias) Parse(ing *extensions.Ingress) (interface{}, error) {
+	return parser.GetStringAnnotation(annotation, ing)
+}

core/pkg/ingress/annotations/alias/main_test.go

@@ -0,0 +1,60 @@
+/*
+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 alias
+
+import (
+	"testing"
+
+	api "k8s.io/api/core/v1"
+	extensions "k8s.io/api/extensions/v1beta1"
+	meta_v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+func TestParse(t *testing.T) {
+	ap := NewParser()
+	if ap == nil {
+		t.Fatalf("expected a parser.IngressAnnotation but returned nil")
+	}
+
+	testCases := []struct {
+		annotations map[string]string
+		expected    string
+	}{
+		{map[string]string{annotation: "www.example.com"}, "www.example.com"},
+		{map[string]string{annotation: "*.example.com www.example.*"}, "*.example.com www.example.*"},
+		{map[string]string{annotation: `~^www\d+\.example\.com$`}, `~^www\d+\.example\.com$`},
+		{map[string]string{annotation: ""}, ""},
+		{map[string]string{}, ""},
+		{nil, ""},
+	}
+
+	ing := &extensions.Ingress{
+		ObjectMeta: meta_v1.ObjectMeta{
+			Name:      "foo",
+			Namespace: api.NamespaceDefault,
+		},
+		Spec: extensions.IngressSpec{},
+	}
+
+	for _, testCase := range testCases {
+		ing.SetAnnotations(testCase.annotations)
+		result, _ := ap.Parse(ing)
+		if result != testCase.expected {
+			t.Errorf("expected %v but returned %v, annotations: %s", testCase.expected, result, testCase.annotations)
+		}
+	}
+}