added rbac example discussed in kubernetes/ingress issue kubernetes#266

examples/rbac/nginx/README.md

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+# Role Based Access Control
+
+This example demontrates how to apply role based access control
+
+## Overview
+
+This example applies to nginx-ingress-controllers being deployed in an
+environment with RBAC enabled.
+
+Role Based Access Control is comprised of four layers:
+
+1.  `ClusterRole` - permissions assigned to a role that apply to an entire cluster
+2.  `ClusterRoleBinding` - binding a ClusterRole to a specific account
+3.  `Role` - permissions assigned to a role that apply to a specific namespace
+4.  `RoleBinding` - binding a Role to a specific account
+
+In order for RBAC to be applied to an nginx-ingress-controller, that controller
+should be assigned to a `ServiceAccount`.  That `ServiceAccount` should be
+bound to the `Role`s and `ClusterRole`s defined for the
+nginx-ingress-controller.
+
+## Service Accounts created in this example
+
+One ServiceAccount is created in this example, `nginx-ingress-serviceaccount`.
+
+## Permissions Granted in this example
+
+There are two sets of permissions defined in this example.  Cluster-wide
+permissions defined by the `ClusterRole` named `nginx-ingress-clusterrole`, and
+namespace specific permissions defined by the `Role` named
+`nginx-ingress-role`.
+
+### Cluster Permissions
+
+These permissions are granted in order for the nginx-ingress-controller to be
+able to function as an ingress across the cluster.  These permissions are
+granted to the ClusterRole named `nginx-ingress-clusterrole`
+
+* `configmaps`, `endpoints`, `nodes`, `pods`, `secrets`: list, watch
+* `services`: get, list, watch, update
+* `ingresses`: get, list, watch
+* `events`: create
+* `ingresses/status`: update
+
+### Namespace Permissions
+
+These permissions are granted specific to the nginx-ingress namespace.  These
+permissions are granted to the Role named `nginx-ingress-role`
+
+* `configmaps`,`secrets`,`pods`: get
+* `endpoints`: get, create, update
+
+### Bindings
+
+The ServiceAccount `nginx-ingress-serviceaccount` is bound to the Role
+`nginx-ingress-role` and the ClusterRole `nginx-ingress-clusterrole`.
+
+## Namespace created in this example
+
+The `Namespace` named `nginx-ingress` is defined in this example.  The
+namespace name can be changed arbitrarily as long as all of the references
+change as well.  
+
+
+## Usage
+
+1.  Create the `Namespace`, `Service Account`, `ClusterRole`, `Role`,
+`ClusterRoleBinding`, and `RoleBinding`.
+
+```sh
+kubectl create -f ./nginx-ingress-controller-rbac.yml
+```
+
+2.  Create the nginx-ingress-controller
+
+For this example to work, the Service must be in the nginx-ingress namespace:
+
+```yaml
+apiVersion: v1
+kind: Service
+metadata:
+  name: nginx-ingress
+  namespace: nginx-ingress #match namespace of service account and role
+spec:
+  type: LoadBalancer
+  ports:
+    - port: 80
+      name: http
+    - port: 443
+      name: https
+  selector:
+    k8s-app: nginx-ingress-lb
+```
+
+The serviceAccountName associated with the containers in the deployment must
+match the serviceAccount from nginx-ingress-controller-rbac.yml  The namespace
+references in the Deployment metadata, container arguments, and POD_NAMESPACE
+should be in the nginx-ingress namespace.
+
+```yaml
+apiVersion: extensions/v1beta1
+kind: Deployment
+metadata:
+  name: nginx-ingress-controller
+  #match namespace of service account and role
+  namespace: nginx-ingress 
+spec:
+  replicas: 2
+  template:
+    metadata:
+      labels:
+        k8s-app: nginx-ingress-lb
+    spec:
+      #match name of service account
+      serviceAccountName: nginx-ingress-serviceaccount
+      containers:
+        - name: nginx-ingress-controller
+          image: gcr.io/google_containers/nginx-ingress-controller:version
+          #namespace matching is required in some arguments
+           args:
+            - /nginx-ingress-controller
+            - --default-backend-service=default/default-http-backend
+            - --default-ssl-certificate=$(POD_NAMESPACE)/tls-certificate
+         env:
+            - name: POD_NAME
+              valueFrom:
+                fieldRef:
+                  fieldPath: metadata.name
+            #match namespace of service account and role
+            - name: POD_NAMESPACE 
+              valueFrom:
+                fieldRef:
+                  fieldPath: metadata.namespace	  
+          ports:
+            - containerPort: 80
+            - containerPort: 443
+
+```

examples/rbac/nginx/nginx-ingress-controller-rbac.yml

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+apiVersion: v1
+kind: Namespace
+metadata:
+  name: nginx-ingress
+---  
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: nginx-ingress-serviceaccount
+  namespace: nginx-ingress
+---  
+apiVersion: rbac.authorization.k8s.io/v1beta1
+kind: ClusterRole
+metadata:
+  name: nginx-ingress-clusterrole
+rules:
+  - apiGroups:
+      - ""
+      - "extensions"
+    resources:
+      - configmaps
+      - secrets
+      - endpoints
+      - nodes
+      - pods
+    verbs:
+      - list
+      - watch
+  - apiGroups:
+      - ""
+    resources:
+      - services
+    verbs:
+      - get
+      - list
+      - watch
+      - update
+  - apiGroups:
+      - "extensions"
+    resources:
+      - ingresses
+    verbs:
+      - get
+      - list
+      - watch
+  - apiGroups:
+      - ""
+    resources:
+        - events
+    verbs:
+        - create
+  - apiGroups:
+      - "extensions"
+    resources:
+      - ingresses/status
+    verbs:
+      - update
+---
+apiVersion: rbac.authorization.k8s.io/v1beta1
+kind: Role
+metadata:
+  name: nginx-ingress-role
+  namespace: nginx-ingress
+rules:
+  - apiGroups:
+      - ""
+    resources:
+      - configmaps
+      - secrets
+      - pods
+    verbs:
+      - get
+  - apiGroups:
+      - ""
+    resources:
+      - endpoints
+    verbs:
+      - get
+      - create
+      - update
+---
+apiVersion: rbac.authorization.k8s.io/v1beta1
+kind: RoleBinding
+metadata:
+  name: nginx-ingress-role-nisa-binding
+  namespace: nginx-ingress
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: Role
+  name: nginx-ingress-role
+subjects:
+  - kind: ServiceAccount
+    name: nginx-ingress-serviceaccount
+    namespace: nginx-ingress
+---
+apiVersion: rbac.authorization.k8s.io/v1beta1
+kind: ClusterRoleBinding
+metadata:
+  name: nginx-ingress-clusterrole-nisa-binding
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: ClusterRole
+  name: nginx-ingress-clusterrole
+subjects:
+  - kind: ServiceAccount
+    name: nginx-ingress-serviceaccount
+    namespace: nginx-ingress
+
+
+
+