static authorizer: add e2e tests, additional verifications

examples/static-auth/README.md

@@ -0,0 +1,201 @@
+# Static Authorization example
+
+> Note to try this out with minikube, make sure you enable RBAC correctly. Since minikube v0.26.0 the default bootstrapper is kubeadm - which should enable RBAC by default. For older version follow the instructions [here](../minikube-rbac).
+
+RBAC differentiates in two types, that need to be authorized, resources and non-resources. A resource request authorization, could for example be, that a requesting entity needs to be authorized to perform the `get` action on a particular Kubernetes Deployment.
+
+In this example we deploy the [prometheus-example-app](https://github.com/brancz/prometheus-example-app) and want to protect it with kube-rbac-proxy, just as detailed in the [rewrite example](../rewrite/README.md). In this example however we will avoid the recurring SubjectAccessReview requests to the api server by allowing kube-rbac-proxy to authorize these requests statically. This is configured in the file passed to the kube-rbac-proxy with the `--config-file` flag. Additionally the `--upstream` flag has to be set to configure the application that should be proxied to on successful authentication as well as authorization.
+
+The kube-rbac-proxy itself also requires RBAC access, in order to perform TokenReviews as well as SubjectAccessReviews for requests that are not statically athorized. These are the APIs available from the Kubernetes API to authenticate and then validate the authorization of an entity.
+
+```bash
+$ kubectl create -f deployment.yaml
+```
+
+The content of this manifest is:
+
+[embedmd]:# (./deployment.yaml)
+```yaml
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: kube-rbac-proxy
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRoleBinding
+metadata:
+  name: kube-rbac-proxy
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: ClusterRole
+  name: kube-rbac-proxy
+subjects:
+- kind: ServiceAccount
+  name: kube-rbac-proxy
+  namespace: default
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  name: kube-rbac-proxy
+rules:
+- apiGroups: ["authentication.k8s.io"]
+  resources:
+  - tokenreviews
+  verbs: ["create"]
+- apiGroups: ["authorization.k8s.io"]
+  resources:
+  - subjectaccessreviews
+  verbs: ["create"]
+---
+apiVersion: v1
+kind: Service
+metadata:
+  labels:
+    app: kube-rbac-proxy
+  name: kube-rbac-proxy
+spec:
+  ports:
+  - name: https
+    port: 8443
+    targetPort: https
+  selector:
+    app: kube-rbac-proxy
+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: kube-rbac-proxy
+data:
+  config-file.yaml: |+
+    authorization:
+      rewrites:
+        byQueryParameter:
+          name: "namespace"
+      resourceAttributes:
+        apiVersion: v1
+        resource: namespace
+        subresource: metrics
+        namespace: "{{ .Value }}"
+      static:
+        - resourceRequest: true
+          resource: namespace
+          subresource: metrics
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: kube-rbac-proxy
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: kube-rbac-proxy
+  template:
+    metadata:
+      labels:
+        app: kube-rbac-proxy
+    spec:
+      securityContext:
+        runAsUser: 65532
+      serviceAccountName: kube-rbac-proxy
+      containers:
+      - name: kube-rbac-proxy
+        image: quay.io/brancz/kube-rbac-proxy:v0.8.0
+        args:
+        - "--secure-listen-address=0.0.0.0:8443"
+        - "--upstream=http://127.0.0.1:8081/"
+        - "--config-file=/etc/kube-rbac-proxy/config-file.yaml"
+        - "--logtostderr=true"
+        - "--v=10"
+        ports:
+        - containerPort: 8443
+          name: https
+        volumeMounts:
+        - name: config
+          mountPath: /etc/kube-rbac-proxy
+        securityContext:
+          allowPrivilegeEscalation: false
+      - name: prometheus-example-app
+        image: quay.io/brancz/prometheus-example-app:v0.1.0
+        args:
+        - "--bind=127.0.0.1:8081"
+      volumes:
+      - name: config
+        configMap:
+          name: kube-rbac-proxy
+```
+
+Once the prometheus-example-app is up and running, we can test it. In order to test it, we deploy a Job, that performs a `curl` against the above deployment. Because it has the correct RBAC roles, the request will succeed.
+
+```bash
+$ kubectl create -f client-rbac.yaml
+```
+
+The content of this manifest is:
+
+[embedmd]:# (./client-rbac.yaml)
+```yaml
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  name: namespace-metrics
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: Role
+  name: namespace-metrics
+subjects:
+- kind: ServiceAccount
+  name: default
+  namespace: default
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: namespace-metrics
+rules:
+- apiGroups: [""]
+  resources:
+  - namespace/metrics
+  verbs: ["get"]
+```
+
+Now simply run
+```
+kubectl run -i -t alpine --image=alpine --restart=Never -- sh -c 'apk add curl; curl -v -s -k -H "Authorization: Bearer `cat /var/run/secrets/kubernetes.io/serviceaccount/token`" https://kube-rbac-proxy.default.svc:8443/metrics?namespace=default'
+```
+
+A configuration setting for the static authorization feature for resource requests looks like this:
+```
+  config-file.yaml: |+
+    authorization:
+      static:
+        - user:
+            name: UserName
+            groups:
+              - group1
+              - group2
+          verb: get
+          namespace: default
+          apiGroup: apps
+          resourceRequest: true
+          resource: namespace
+          subresource: metrics
+```
+
+A configuration setting for the static authorization feature for non-resource requests looks like this:
+```
+  config-file.yaml: |+
+    authorization:
+      static:
+        - user:
+            name: UserName
+            groups:
+              - group1
+              - group2
+          verb: get
+          resourceRequest: false
+          path: /metrics
+```
+
+The values in the above example are just aimed at illustrating what is possible. An omitted configuration setting is interpreted as a wildcard. E.g. if a static-auth configuration omits the `user` setting, any user can be statically authorized if a request fits the remaining configuration.

examples/static-auth/client-rbac.yaml

@@ -0,0 +1,22 @@
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  name: namespace-metrics
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: Role
+  name: namespace-metrics
+subjects:
+- kind: ServiceAccount
+  name: default
+  namespace: default
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: namespace-metrics
+rules:
+- apiGroups: [""]
+  resources:
+  - namespace/metrics
+  verbs: ["get"]

examples/static-auth/deployment.yaml

@@ -0,0 +1,108 @@
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: kube-rbac-proxy
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRoleBinding
+metadata:
+  name: kube-rbac-proxy
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: ClusterRole
+  name: kube-rbac-proxy
+subjects:
+- kind: ServiceAccount
+  name: kube-rbac-proxy
+  namespace: default
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  name: kube-rbac-proxy
+rules:
+- apiGroups: ["authentication.k8s.io"]
+  resources:
+  - tokenreviews
+  verbs: ["create"]
+- apiGroups: ["authorization.k8s.io"]
+  resources:
+  - subjectaccessreviews
+  verbs: ["create"]
+---
+apiVersion: v1
+kind: Service
+metadata:
+  labels:
+    app: kube-rbac-proxy
+  name: kube-rbac-proxy
+spec:
+  ports:
+  - name: https
+    port: 8443
+    targetPort: https
+  selector:
+    app: kube-rbac-proxy
+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: kube-rbac-proxy
+data:
+  config-file.yaml: |+
+    authorization:
+      rewrites:
+        byQueryParameter:
+          name: "namespace"
+      resourceAttributes:
+        apiVersion: v1
+        resource: namespace
+        subresource: metrics
+        namespace: "{{ .Value }}"
+      static:
+        - resourceRequest: true
+          resource: namespace
+          subresource: metrics
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: kube-rbac-proxy
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: kube-rbac-proxy
+  template:
+    metadata:
+      labels:
+        app: kube-rbac-proxy
+    spec:
+      securityContext:
+        runAsUser: 65532
+      serviceAccountName: kube-rbac-proxy
+      containers:
+      - name: kube-rbac-proxy
+        image: quay.io/brancz/kube-rbac-proxy:v0.8.0
+        args:
+        - "--secure-listen-address=0.0.0.0:8443"
+        - "--upstream=http://127.0.0.1:8081/"
+        - "--config-file=/etc/kube-rbac-proxy/config-file.yaml"
+        - "--logtostderr=true"
+        - "--v=10"
+        ports:
+        - containerPort: 8443
+          name: https
+        volumeMounts:
+        - name: config
+          mountPath: /etc/kube-rbac-proxy
+        securityContext:
+          allowPrivilegeEscalation: false
+      - name: prometheus-example-app
+        image: quay.io/brancz/prometheus-example-app:v0.1.0
+        args:
+        - "--bind=127.0.0.1:8081"
+      volumes:
+      - name: config
+        configMap:
+          name: kube-rbac-proxy

main.go

@@ -37,6 +37,7 @@ import (
 	"golang.org/x/net/http2"
 	"golang.org/x/net/http2/h2c"
 	"k8s.io/apiserver/pkg/authentication/authenticator"
+	"k8s.io/apiserver/pkg/authorization/union"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/clientcmd"
@@ -184,12 +185,22 @@ func main() {
 	}
 
 	sarClient := kubeClient.AuthorizationV1().SubjectAccessReviews()
-	authorizer, err := authz.NewAuthorizer(sarClient)
+	sarAuthorizer, err := authz.NewSarAuthorizer(sarClient)
 
 	if err != nil {
-		klog.Fatalf("Failed to create authorizer: %v", err)
+		klog.Fatalf("Failed to create sar authorizer: %v", err)
 	}
 
+	staticAuthorizer, err := authz.NewStaticAuthorizer(cfg.auth.Authorization.Static)
+	if err != nil {
+		klog.Fatalf("Failed to create static authorizer: %v", err)
+	}
+
+	authorizer := union.New(
+		staticAuthorizer,
+		sarAuthorizer,
+	)
+
 	auth, err := proxy.New(kubeClient, cfg.auth, authorizer, authenticator)
 
 	if err != nil {