Add annotation to customize nginx location configuration

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

@@ -331,6 +331,9 @@ http {
             proxy_set_header                        Accept-Encoding     "";
             {{ end }}
 
+            {{/* Add any additional configuration defined */}}
+            {{ $location.ConfigurationSnippet }}
+
             {{ buildProxyPass $backends $location }}
             {{ else }}
             #{{ $location.Denied }}

core/pkg/ingress/annotations/snippet/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 snippet
+
+import (
+	"k8s.io/kubernetes/pkg/apis/extensions"
+
+	"k8s.io/ingress/core/pkg/ingress/annotations/parser"
+)
+
+const (
+	annotation = "ingress.kubernetes.io/configuration-snippet"
+)
+
+type snippet struct {
+}
+
+// NewParser creates a new CORS annotation parser
+func NewParser() parser.IngressAnnotation {
+	return snippet{}
+}
+
+// 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 snippet) Parse(ing *extensions.Ingress) (interface{}, error) {
+	return  parser.GetStringAnnotation(annotation, ing)
+}

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

@@ -0,0 +1,57 @@
+/*
+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 snippet
+
+import (
+	"testing"
+
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/apis/extensions"
+)
+
+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: "more_headers"}, "more_headers"},
+		{map[string]string{annotation: "false"}, "false"},
+		{map[string]string{}, ""},
+		{nil, ""},
+	}
+
+	ing := &extensions.Ingress{
+		ObjectMeta: api.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

@@ -34,6 +34,7 @@ import (
 	"k8s.io/ingress/core/pkg/ingress/annotations/rewrite"
 	"k8s.io/ingress/core/pkg/ingress/annotations/secureupstream"
 	"k8s.io/ingress/core/pkg/ingress/annotations/sessionaffinity"
+	"k8s.io/ingress/core/pkg/ingress/annotations/snippet"
 	"k8s.io/ingress/core/pkg/ingress/annotations/sslpassthrough"
 	"k8s.io/ingress/core/pkg/ingress/errors"
 	"k8s.io/ingress/core/pkg/ingress/resolver"
@@ -65,6 +66,7 @@ func newAnnotationExtractor(cfg extractorConfig) annotationExtractor {
 			"SecureUpstream":       secureupstream.NewParser(),
 			"SessionAffinity":      sessionaffinity.NewParser(),
 			"SSLPassthrough":       sslpassthrough.NewParser(),
+			"ConfigurationSnippet": snippet.NewParser(),
 		},
 	}
 }

core/pkg/ingress/types.go

@@ -277,6 +277,9 @@ type Location struct {
 	// UsePortInRedirects indicates if redirects must specify the port
 	// +optional
 	UsePortInRedirects bool `json:"use-port-in-redirects"`
+	// ConfigurationSnippet contains additional configuration for the backend
+	// to be considered in the configuration of the location
+	ConfigurationSnippet string `json:"configuration-snippet"`
 }
 
 // SSLPassthroughBackend describes a SSL upstream server configured

examples/README.md

@@ -80,3 +80,4 @@ Dummy  | A simple dummy controller that logs updates | * | Advanced
 Name | Description | Platform   | Complexity Level
 -----| ----------- | ---------- | ----------------
 custom-headers  | set custom headers before send traffic to backends  | nginx | Advanced
+configuration-snippets | customize nginx location configuration using annotations | nginx | Advanced

examples/customization/configuration-snippets/nginx/README.md

@@ -0,0 +1,44 @@
+# Deploying the Nginx Ingress controller
+
+This example aims to demonstrate the deployment of an nginx ingress controller and
+with the use of an annotation in the Ingress rule be able to customize the nginx 
+configuration.
+
+## Default Backend
+
+The default backend is a Service capable of handling all url paths and hosts the
+nginx controller doesn't understand. This most basic implementation just returns
+a 404 page:
+
+```console
+$ kubectl apply -f default-backend.yaml
+deployment "default-http-backend" created
+service "default-http-backend" created
+
+$ kubectl -n kube-system get po
+NAME                                    READY     STATUS    RESTARTS   AGE
+default-http-backend-2657704409-qgwdd   1/1       Running   0          28s
+```
+
+```console
+$ kubectl create -f nginx-load-balancer-conf.yaml
+```
+
+## Controller
+
+You can deploy the controller as follows:
+
+```console
+$ kubectl apply -f nginx-ingress-controller.yaml
+deployment "nginx-ingress-controller" created
+
+$ kubectl -n kube-system get po
+NAME                                       READY     STATUS    RESTARTS   AGE
+default-http-backend-2657704409-qgwdd      1/1       Running   0          2m
+nginx-ingress-controller-873061567-4n3k2   1/1       Running   0          42s
+```
+
+## Test
+
+Check the contents of the annotation is present in the nginx.conf file using:
+`kubectl exec nginx-ingress-controller-873061567-4n3k2 -n kube-system cat /etc/nginx/nginx.conf`

examples/customization/configuration-snippets/nginx/default-backend.yaml

@@ -0,0 +1,51 @@
+apiVersion: extensions/v1beta1
+kind: Deployment
+metadata:
+  name: default-http-backend
+  labels:
+    k8s-app: default-http-backend
+  namespace: kube-system
+spec:
+  replicas: 1
+  template:
+    metadata:
+      labels:
+        k8s-app: default-http-backend
+    spec:
+      terminationGracePeriodSeconds: 60
+      containers:
+      - name: default-http-backend
+        # Any image is permissable as long as:
+        # 1. It serves a 404 page at /
+        # 2. It serves 200 on a /healthz endpoint
+        image: gcr.io/google_containers/defaultbackend:1.0
+        livenessProbe:
+          httpGet:
+            path: /healthz
+            port: 8080
+            scheme: HTTP
+          initialDelaySeconds: 30
+          timeoutSeconds: 5
+        ports:
+        - containerPort: 8080
+        resources:
+          limits:
+            cpu: 10m
+            memory: 20Mi
+          requests:
+            cpu: 10m
+            memory: 20Mi
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: default-http-backend
+  namespace: kube-system
+  labels:
+    k8s-app: default-http-backend
+spec:
+  ports:
+  - port: 80
+    targetPort: 8080
+  selector:
+    k8s-app: default-http-backend

examples/customization/configuration-snippets/nginx/ingress.yaml

@@ -0,0 +1,18 @@
+apiVersion: extensions/v1beta1
+kind: Ingress
+metadata:
+  name: nginx-configuration-snippet
+  annotations:
+    kubernetes.io/ingress.class: "nginx"
+    ingress.kubernetes.io/configuration-snippet: |
+      more_set_headers "Request-Id: $request_id";
+
+spec:
+  rules:
+  - host: custom.configuration.com
+    http:
+      paths:
+      - backend:
+          serviceName: http-svc
+          servicePort: 80
+        path: /

examples/customization/configuration-snippets/nginx/nginx-ingress-controller.yaml

@@ -0,0 +1,53 @@
+apiVersion: extensions/v1beta1
+kind: Deployment
+metadata:
+  name: nginx-ingress-controller
+  labels:
+    k8s-app: nginx-ingress-controller
+  namespace: kube-system
+spec:
+  replicas: 1
+  template:
+    metadata:
+      labels:
+        k8s-app: nginx-ingress-controller
+    spec:
+      # hostNetwork makes it possible to use ipv6 and to preserve the source IP correctly regardless of docker configuration
+      # however, it is not a hard dependency of the nginx-ingress-controller itself and it may cause issues if port 10254 already is taken on the host
+      # that said, since hostPort is broken on CNI (https://github.com/kubernetes/kubernetes/issues/31307) we have to use hostNetwork where CNI is used
+      # like with kubeadm
+      # hostNetwork: true
+      terminationGracePeriodSeconds: 60
+      containers:
+      - image: gcr.io/google_containers/nginx-ingress-controller:0.9.0-beta.2
+        name: nginx-ingress-controller
+        readinessProbe:
+          httpGet:
+            path: /healthz
+            port: 10254
+            scheme: HTTP
+        livenessProbe:
+          httpGet:
+            path: /healthz
+            port: 10254
+            scheme: HTTP
+          initialDelaySeconds: 10
+          timeoutSeconds: 1
+        ports:
+        - containerPort: 80
+          hostPort: 80
+        - containerPort: 443
+          hostPort: 443
+        env:
+          - name: POD_NAME
+            valueFrom:
+              fieldRef:
+                fieldPath: metadata.name
+          - name: POD_NAMESPACE
+            valueFrom:
+              fieldRef:
+                fieldPath: metadata.namespace
+        args:
+        - /nginx-ingress-controller
+        - --default-backend-service=$(POD_NAMESPACE)/default-http-backend
+        - --configmap=$(POD_NAMESPACE)/nginx-load-balancer-conf

examples/customization/configuration-snippets/nginx/nginx-load-balancer-conf.yaml

@@ -0,0 +1,7 @@
+apiVersion: v1
+data:
+  proxy-set-headers: "kube-system/custom-headers"
+kind: ConfigMap
+metadata:
+  name: nginx-load-balancer-conf
+  namespace: kube-system