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.

controllers/nginx/configuration.md

@@ -64,7 +64,7 @@ The following annotations are supported:
 |[ingress.kubernetes.io/upstream-max-fails](#custom-nginx-upstream-checks)|number|
 |[ingress.kubernetes.io/upstream-fail-timeout](#custom-nginx-upstream-checks)|number|
 |[ingress.kubernetes.io/whitelist-source-range](#whitelist-source-range)|CIDR|
-
+|[ingress.kubernetes.io/server-alias](#server-alias)|string|
 
 
 #### Custom NGINX template
@@ -155,7 +155,7 @@ Please check the [tls-auth](/examples/auth/client-certs/nginx/README.md) example
 
 ### Configuration snippet
 
-Using this annotion you can add additional configuration to the NGINX location. For example:
+Using this annotation you can add additional configuration to the NGINX location. For example:
 
 ```
 ingress.kubernetes.io/configuration-snippet: |
@@ -167,6 +167,17 @@ ingress.kubernetes.io/configuration-snippet: |
 To enable Cross-Origin Resource Sharing (CORS) in an Ingress rule add the annotation `ingress.kubernetes.io/enable-cors: "true"`. This will add a section in the server location enabling this functionality.
 For more information please check https://enable-cors.org/server_nginx.html
 
+### Server Alias
+
+To add Server Aliases to an Ingress rule add the annotation `ingress.kubernetes.io/server-alias: "<server-name_0>:<server-alias_0>;...;<server-name_n>:<server-alias_n>"`.
+This will append a server-alias to the end of the server_name in the NGINX server. A server-alias can accept wildcards, but
+it cannot accept port numbers.
+
+The server-name must match a valid server within the ingress resource for it to append the server-alias. Multiple server-aliases
+can be added for multiple server-names using `;` as a delimiter.
+
+For more information please see http://nginx.org/en/docs/http/ngx_http_core_module.html#server_name
+
 ### External Authentication
 
 To use an existing service that provides authentication the Ingress rule can be annotated with `ingress.kubernetes.io/auth-url` to indicate the URL where the HTTP request should be sent.

controllers/nginx/pkg/cmd/controller/nginx.go

@@ -452,6 +452,7 @@ func (n *NGINXController) OnUpdate(ingressCfg ingress.Configuration) error {
 			IP:            svc.Spec.ClusterIP,
 			Port:          port,
 			ProxyProtocol: false,
+
 		})
 	}
 

controllers/nginx/rootfs/etc/nginx/template/nginx.tmpl

@@ -295,7 +295,7 @@ http {
     {{ $backlogSize := .BacklogSize }}
     {{ range $index, $server := .Servers }}
     server {
-        server_name {{ $server.Hostname }};
+        server_name {{ $server.Hostname }} {{ $server.Alias }};
         listen 80{{ if $cfg.UseProxyProtocol }} proxy_protocol{{ end }}{{ if eq $server.Hostname "_"}} default_server reuseport backlog={{ $backlogSize }}{{end}};
         {{ if $IsIPV6Enabled }}listen [::]:80{{ if $cfg.UseProxyProtocol }} proxy_protocol{{ end }}{{ if eq $server.Hostname "_"}} default_server reuseport backlog={{ $backlogSize }}{{ end }};{{ end }}
         set $proxy_upstream_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)
+		}
+	}
+}

core/pkg/ingress/controller/annotations.go

@@ -37,6 +37,7 @@ import (
 	"k8s.io/ingress/core/pkg/ingress/annotations/sslpassthrough"
 	"k8s.io/ingress/core/pkg/ingress/errors"
 	"k8s.io/ingress/core/pkg/ingress/resolver"
+	"k8s.io/ingress/core/pkg/ingress/annotations/alias"
 )
 
 type extractorConfig interface {
@@ -69,6 +70,7 @@ func newAnnotationExtractor(cfg extractorConfig) annotationExtractor {
 			"SessionAffinity":      sessionaffinity.NewParser(),
 			"SSLPassthrough":       sslpassthrough.NewParser(),
 			"ConfigurationSnippet": snippet.NewParser(),
+			"Alias":                alias.NewParser(),
 		},
 	}
 }
@@ -107,6 +109,7 @@ const (
 	sslPassthrough  = "SSLPassthrough"
 	sessionAffinity = "SessionAffinity"
 	serviceUpstream = "ServiceUpstream"
+	serverAlias     = "Alias"
 )
 
 func (e *annotationExtractor) ServiceUpstream(ing *extensions.Ingress) bool {
@@ -133,6 +136,11 @@ func (e *annotationExtractor) SSLPassthrough(ing *extensions.Ingress) bool {
 	return val.(bool)
 }
 
+func (e *annotationExtractor) Alias(ing *extensions.Ingress) string {
+	val, _ := e.annotations[serverAlias].Parse(ing)
+	return val.(string)
+}
+
 func (e *annotationExtractor) SessionAffinity(ing *extensions.Ingress) *sessionaffinity.AffinityConfig {
 	val, _ := e.annotations[sessionAffinity].Parse(ing)
 	return val.(*sessionaffinity.AffinityConfig)

core/pkg/ingress/controller/controller.go

@@ -1055,19 +1055,37 @@ func (ic *GenericController) createServers(data []interface{},
 		}
 	}
 
-	// configure default location and SSL
+	// configure default location, alias, and SSL
 	for _, ingIf := range data {
 		ing := ingIf.(*extensions.Ingress)
 		if !class.IsValid(ing, ic.cfg.IngressClass, ic.cfg.DefaultIngressClass) {
 			continue
 		}
 
+		// setup server-aliases based on annotations
+		aliasMap := map[string]string{}
+		aliasAnnotation := ic.annotations.Alias(ing)
+
+		// Here we parse the annotation string in the following format:
+		// ingress.kubernetes.io/server-alias: "host_0:alias_0;...;host_n:alias_n"
+		aliases := strings.Split(aliasAnnotation, ";")
+		for _, alias := range aliases {
+			aliasParts := strings.Split(alias, ":")
+			if len(aliasParts) == 2 {
+				// aliasMap[host] = alias
+				aliasMap[aliasParts[0]] = aliasParts[1]
+			}
+		}
+
 		for _, rule := range ing.Spec.Rules {
 			host := rule.Host
 			if host == "" {
 				host = defServerName
 			}
 
+			// setup server aliases
+			servers[host].Alias = aliasMap[host]
+
 			// only add a certificate if the server does not have one previously configured
 			if len(ing.Spec.TLS) == 0 || servers[host].SSLCertificate != "" {
 				continue

core/pkg/ingress/types.go

@@ -220,6 +220,8 @@ type Server struct {
 	SSLPemChecksum string `json:"sslPemChecksum"`
 	// Locations list of URIs configured in the server.
 	Locations []*Location `json:"locations,omitempty"`
+	// return the alias of the server name
+	Alias string `json:"alias,omitempty"`
 }
 
 // Location describes an URI inside a server.