Limit manager to given namespace

This should improve security; controller will only be able to check secrets in it's own namespace.
It also has the potential to lower resource usage drastically on bigger clusters with many objects.

config/manager/manager.yaml

@@ -43,6 +43,7 @@ spec:
       containers:
       - args:
         - --leader-elect
+        - --namespace=$(POD_NAMESPACE)
         env:
         - name: POD_NAMESPACE
           valueFrom:

config/rbac/role.yaml

@@ -4,6 +4,19 @@ kind: ClusterRole
 metadata:
   name: manager-role
 rules:
+- apiGroups:
+  - authentication.k8s.io
+  resources:
+  - tokenreviews
+  verbs:
+  - create
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: manager-role
+  namespace: system
+rules:
 - apiGroups:
   - ""
   resources:
@@ -33,12 +46,6 @@ rules:
   - serviceaccounts/token
   verbs:
   - create
-- apiGroups:
-  - authentication.k8s.io
-  resources:
-  - tokenreviews
-  verbs:
-  - create
 - apiGroups:
   - cluster.appuio.io
   resources:

config/rbac/role_binding.yaml

@@ -17,3 +17,23 @@ subjects:
 - kind: ServiceAccount
   name: controller-manager
   namespace: system
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  labels:
+    app.kubernetes.io/name: rolebinding
+    app.kubernetes.io/instance: manager-rolebinding
+    app.kubernetes.io/component: rbac
+    app.kubernetes.io/created-by: emergency-credentials-controller
+    app.kubernetes.io/part-of: emergency-credentials-controller
+    app.kubernetes.io/managed-by: kustomize
+  name: manager-rolebinding
+  namespace: system
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: Role
+  name: manager-role
+subjects:
+- kind: ServiceAccount
+  name: controller-manager

controllers/emergencyaccount_controller.go

@@ -35,12 +35,12 @@ type EmergencyAccountReconciler struct {
 	Clock Clock
 }
 
-//+kubebuilder:rbac:groups=cluster.appuio.io,resources=emergencyaccounts,verbs=get;list;watch;create;update;patch;delete
-//+kubebuilder:rbac:groups=cluster.appuio.io,resources=emergencyaccounts/status,verbs=get;update;patch
-//+kubebuilder:rbac:groups=cluster.appuio.io,resources=emergencyaccounts/finalizers,verbs=update
+//+kubebuilder:rbac:groups=cluster.appuio.io,resources=emergencyaccounts,verbs=get;list;watch;create;update;patch;delete,namespace="system"
+//+kubebuilder:rbac:groups=cluster.appuio.io,resources=emergencyaccounts/status,verbs=get;update;patch,namespace="system"
+//+kubebuilder:rbac:groups=cluster.appuio.io,resources=emergencyaccounts/finalizers,verbs=update,namespace="system"
 
-//+kubebuilder:rbac:groups="",resources=serviceaccounts,verbs=get;list;watch;create;update;patch;delete
-//+kubebuilder:rbac:groups="",resources=serviceaccounts/token,verbs=create
+//+kubebuilder:rbac:groups="",resources=serviceaccounts,verbs=get;list;watch;create;update;patch;delete,namespace="system"
+//+kubebuilder:rbac:groups="",resources=serviceaccounts/token,verbs=create,namespace="system"
 
 //+kubebuilder:rbac:groups=authentication.k8s.io,resources=tokenreviews,verbs=create
 

controllers/stores/secret_store.go

@@ -16,7 +16,7 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/log"
 )
 
-//+kubebuilder:rbac:groups="",resources=secrets,verbs=get;list;watch;create;update;patch
+//+kubebuilder:rbac:groups="",resources=secrets,verbs=get;list;watch;create;update;patch,namespace="system"
 
 type SecretStore struct {
 	SecretStoreSpec emcv1beta1.SecretStoreSpec

main.go

@@ -8,12 +8,14 @@ import (
 	// Import all Kubernetes client auth plugins (e.g. Azure, GCP, OIDC, etc.)
 	// to ensure that exec-entrypoint and run can make use of them.
 	_ "k8s.io/client-go/plugin/pkg/client/auth"
+	"k8s.io/client-go/rest"
 
 	authenticationv1 "k8s.io/api/authentication/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
 	clientgoscheme "k8s.io/client-go/kubernetes/scheme"
 	ctrl "sigs.k8s.io/controller-runtime"
+	"sigs.k8s.io/controller-runtime/pkg/cache"
 	"sigs.k8s.io/controller-runtime/pkg/healthz"
 	"sigs.k8s.io/controller-runtime/pkg/log/zap"
 	"sigs.k8s.io/controller-runtime/pkg/metrics/server"
@@ -40,11 +42,13 @@ func main() {
 	var metricsAddr string
 	var enableLeaderElection bool
 	var probeAddr string
+	var namespace string
 	flag.StringVar(&metricsAddr, "metrics-bind-address", ":8080", "The address the metric endpoint binds to.")
 	flag.StringVar(&probeAddr, "health-probe-bind-address", ":8081", "The address the probe endpoint binds to.")
 	flag.BoolVar(&enableLeaderElection, "leader-elect", false,
 		"Enable leader election for controller manager. "+
 			"Enabling this will ensure there is only one active controller manager.")
+	flag.StringVar(&namespace, "namespace", "default", "The namespace to watch for EmergencyAccount resources.")
 	opts := zap.Options{
 		Development: true,
 	}
@@ -53,6 +57,7 @@ func main() {
 
 	ctrl.SetLogger(zap.New(zap.UseFlagOptions(&opts)))
 
+	setupLog.Info("limiting manager and cache to namespace", "namespace", namespace)
 	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), ctrl.Options{
 		Scheme: scheme,
 		Metrics: server.Options{
@@ -72,6 +77,14 @@ func main() {
 		// if you are doing or is intended to do any operation such as perform cleanups
 		// after the manager stops then its usage might be unsafe.
 		// LeaderElectionReleaseOnCancel: true,
+
+		// Limit the manager to only watch the namespace the controller is running in.
+		NewCache: func(config *rest.Config, opts cache.Options) (cache.Cache, error) {
+			opts.DefaultNamespaces = map[string]cache.Config{
+				namespace: {},
+			}
+			return cache.New(config, opts)
+		},
 	})
 	if err != nil {
 		setupLog.Error(err, "unable to start manager")