Added handling of ingress.class annotation for NGINX

Author: pleshakov

README.md

@@ -44,6 +44,10 @@ Every time the number of pods of services you expose via Ingress changes, the In
 NGINX Plus provides you with [advanced statistics](https://www.nginx.com/products/live-activity-monitoring/), which you can access either through the API or via the built-in dashboard. This can give you insights into how NGINX Plus and your applications are performing.
 * **Session Persistence** When enabled, NGINX Plus makes sure that all the requests from the same client are always passed to the same backend container using the *sticky cookie* method. Refer to the [session persistence examples](examples/session-persistence) to find out how to configure it.
 
+## Using Multiple Ingress Controllers
+
+You can run multiple Ingress controllers at the same time. For example, if your Kubernetes cluster is deployed in cloud, you can run the NGINX controller and the corresponding cloud HTTP load balancing controller. Refer to the [example](examples/multiple-ingress-controllers) to learn more.
+
 ## Advanced load balancing (beyond Ingress)
 
 When your requirements go beyond what Ingress offers, you can use NGINX and

examples/multiple-ingress-controllers/README.md

@@ -0,0 +1,45 @@
+# Using Multiple Ingress Controllers
+
+With the *kubernetes.io/ingress.class* annotation it is possible to smoothly run multiple Ingress controllers at the same time. This could be the case when you deploy your Kubernetes cluster in a cloud provider, for example, Google Compute Engine (GCE). A cloud provider can provide its own Ingress controller enabled by default.
+
+If the annotation is not present in an Ingress resource, which is the usual case, each Ingress controller deployed in the cluster will handle that Ingress. Using the annotation you can specify which Ingress controller must handle which Ingress resource.
+
+To designate that a particular Ingress resource must be handled *only* by the NGINX or NGINX Plus controller add the following annotation along with the value to the Ingress resource:
+```
+kubernetes.io/ingress.class: "nginx"
+```
+
+In this case other Ingress controllers will ignore that Ingress.
+
+To summarize, the NGINX or NGINX Plus controller *will* handle an Ingress resource, if one of the following is true:
+* The annotation is not present in the resource
+* The annotation is present and its value is either the `nginx` or the empty string
+
+Any other value of the annotation, for example, `gce`, makes the NGINX or NGINX Plus controller ignore the Ingress resource.
+
+Here is an example of an Ingress resource that will be handled *only* by the NGINX or NGINX Plus controller:
+```yaml
+apiVersion: extensions/v1beta1
+kind: Ingress
+metadata:
+  name: cafe-ingress-nginx
+  annotations:
+    kubernetes.io/ingress.class: "nginx"
+spec:
+  tls:
+  - hosts:
+    - cafe.example.com
+    secretName: cafe-secret
+  rules:
+  - host: cafe.example.com
+    http:
+      paths:
+      - path: /tea
+        backend:
+          serviceName: tea-svc
+          servicePort: 80
+      - path: /coffee
+        backend:
+          serviceName: coffee-svc
+          servicePort: 80
+```

nginx-controller/controller/controller.go

@@ -34,6 +34,11 @@ import (
 	"k8s.io/kubernetes/pkg/watch"
 )
 
+const (
+	ingressClassKey   = "kubernetes.io/ingress.class"
+	nginxIngressClass = "nginx"
+)
+
 // LoadBalancerController watches Kubernetes API and
 // reconfigures NGINX via NginxController when needed
 type LoadBalancerController struct {
@@ -70,18 +75,28 @@ func NewLoadBalancerController(kubeClient *client.Client, resyncPeriod time.Dura
 	ingHandlers := framework.ResourceEventHandlerFuncs{
 		AddFunc: func(obj interface{}) {
 			addIng := obj.(*extensions.Ingress)
+			if !isNginxIngress(addIng) {
+				glog.Infof("Ignoring Ingress %v based on Annotation %v", addIng.Name, ingressClassKey)
+				return
+			}
 			glog.V(3).Infof("Adding Ingress: %v", addIng.Name)
 			lbc.ingQueue.enqueue(obj)
 		},
 		DeleteFunc: func(obj interface{}) {
 			remIng := obj.(*extensions.Ingress)
+			if !isNginxIngress(remIng) {
+				return
+			}
 			glog.V(3).Infof("Removing Ingress: %v", remIng.Name)
 			lbc.ingQueue.enqueue(obj)
 		},
 		UpdateFunc: func(old, cur interface{}) {
+			curIng := cur.(*extensions.Ingress)
+			if !isNginxIngress(curIng) {
+				return
+			}
 			if !reflect.DeepEqual(old, cur) {
-				glog.V(3).Infof("Ingress %v changed, syncing",
-					cur.(*extensions.Ingress).Name)
+				glog.V(3).Infof("Ingress %v changed, syncing", curIng.Name)
 				lbc.ingQueue.enqueue(cur)
 			}
 		},
@@ -440,3 +455,11 @@ func parseNginxConfigMaps(nginxConfigMaps string) (string, string, error) {
 	}
 	return res[0], res[1], nil
 }
+
+func isNginxIngress(ing *extensions.Ingress) bool {
+	if class, exists := ing.Annotations[ingressClassKey]; exists {
+		return class == nginxIngressClass || class == ""
+	}
+
+	return true
+}

nginx-plus-controller/controller/controller.go

@@ -34,6 +34,11 @@ import (
 	"k8s.io/kubernetes/pkg/watch"
 )
 
+const (
+	ingressClassKey   = "kubernetes.io/ingress.class"
+	nginxIngressClass = "nginx"
+)
+
 // LoadBalancerController watches Kubernetes API and
 // reconfigures NGINX via NginxController when needed
 type LoadBalancerController struct {
@@ -70,18 +75,28 @@ func NewLoadBalancerController(kubeClient *client.Client, resyncPeriod time.Dura
 	ingHandlers := framework.ResourceEventHandlerFuncs{
 		AddFunc: func(obj interface{}) {
 			addIng := obj.(*extensions.Ingress)
+			if !isNginxIngress(addIng) {
+				glog.Infof("Ignoring Ingress %v based on Annotation %v", addIng.Name, ingressClassKey)
+				return
+			}
 			glog.V(3).Infof("Adding Ingress: %v", addIng.Name)
 			lbc.ingQueue.enqueue(obj)
 		},
 		DeleteFunc: func(obj interface{}) {
 			remIng := obj.(*extensions.Ingress)
+			if !isNginxIngress(remIng) {
+				return
+			}
 			glog.V(3).Infof("Removing Ingress: %v", remIng.Name)
 			lbc.ingQueue.enqueue(obj)
 		},
 		UpdateFunc: func(old, cur interface{}) {
+			curIng := cur.(*extensions.Ingress)
+			if !isNginxIngress(curIng) {
+				return
+			}
 			if !reflect.DeepEqual(old, cur) {
-				glog.V(3).Infof("Ingress %v changed, syncing",
-					cur.(*extensions.Ingress).Name)
+				glog.V(3).Infof("Ingress %v changed, syncing", curIng.Name)
 				lbc.ingQueue.enqueue(cur)
 			}
 		},
@@ -440,3 +455,11 @@ func parseNginxConfigMaps(nginxConfigMaps string) (string, string, error) {
 	}
 	return res[0], res[1], nil
 }
+
+func isNginxIngress(ing *extensions.Ingress) bool {
+	if class, exists := ing.Annotations[ingressClassKey]; exists {
+		return class == nginxIngressClass || class == ""
+	}
+
+	return true
+}