cmd/main: add back the --namespace flag

cmd/main.go

@@ -26,6 +26,7 @@ import (
 	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"
 	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
@@ -49,17 +50,21 @@ func init() {
 }
 
 func main() {
-	var metricsAddr string
-	var pprofAddr string
-	var enableLeaderElection bool
-	var probeAddr string
-	var zkQuorum string
+	var (
+		metricsAddr          string
+		pprofAddr            string
+		enableLeaderElection bool
+		probeAddr            string
+		namespace            string
+		zkQuorum             string
+	)
 	flag.StringVar(&metricsAddr, "metrics-addr", ":8080", "The address the metric endpoint binds to.")
 	flag.StringVar(&pprofAddr, "pprof-addr", ":6060", "The address the pprof 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", "hbase", "The namespace to watch for resource definitions.")
 	flag.StringVar(&zkQuorum, "zkquorum", "localhost:2181",
 		"Comma-separated list of zookeeper addresses.")
 
@@ -71,8 +76,18 @@ func main() {
 
 	ctrl.SetLogger(zap.New(zap.UseFlagOptions(&opts)))
 
+	var watchNamespaces map[string]cache.Config
+	if namespace != "" {
+		watchNamespaces = map[string]cache.Config{
+			namespace: {},
+		}
+	}
+
 	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), ctrl.Options{
 		Scheme: scheme,
+		Cache: cache.Options{
+			DefaultNamespaces: watchNamespaces,
+		},
 		Metrics: metricsserver.Options{
 			BindAddress: metricsAddr,
 		},