Add custom backend annotation

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

@@ -0,0 +1,57 @@
+/*
+Copyright 2015 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 defaultbackend
+
+import (
+	"fmt"
+
+	"github.com/pkg/errors"
+	extensions "k8s.io/api/extensions/v1beta1"
+
+	"k8s.io/ingress/core/pkg/ingress/annotations/parser"
+	"k8s.io/ingress/core/pkg/ingress/resolver"
+)
+
+const (
+	defaultBackend = "ingress.kubernetes.io/default-backend"
+)
+
+type backend struct {
+	serviceResolver resolver.Service
+}
+
+// NewParser creates a new default backend annotation parser
+func NewParser(sr resolver.Service) parser.IngressAnnotation {
+	return backend{sr}
+}
+
+// Parse parses the annotations contained in the ingress to use
+// a custom default backend
+func (db backend) Parse(ing *extensions.Ingress) (interface{}, error) {
+	s, err := parser.GetStringAnnotation(defaultBackend, ing)
+	if err != nil {
+		return nil, err
+	}
+
+	name := fmt.Sprintf("%v/%v", ing.Namespace, s)
+	svc, err := db.serviceResolver.GetService(s)
+	if err != nil {
+		return nil, errors.Wrapf(err, "unexpected error reading service %v", name)
+	}
+
+	return svc, nil
+}