PCP-2739: Support watchNamespace allowing controller to watch objects…

… in the specified namespace (#17)

go.mod

@@ -59,7 +59,7 @@ require (
 	github.com/prometheus/client_model v0.3.0 // indirect
 	github.com/prometheus/common v0.37.0 // indirect
 	github.com/prometheus/procfs v0.8.0 // indirect
-	github.com/spf13/pflag v1.0.5 // indirect
+	github.com/spf13/pflag v1.0.5
 	go.uber.org/atomic v1.10.0 // indirect
 	go.uber.org/multierr v1.8.0 // indirect
 	go.uber.org/zap v1.23.0 // indirect

main.go

@@ -19,7 +19,6 @@ package main
 import (
 	"flag"
 	"os"
-
 	// 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"
@@ -43,9 +42,13 @@ import (
 var (
 	scheme   = runtime.NewScheme()
 	setupLog = ctrl.Log.WithName("setup")
+
+	// flags
+
 )
 
 func init() {
+
 	utilruntime.Must(clientgoscheme.AddToScheme(scheme))
 	utilruntime.Must(clusterv1.AddToScheme(scheme))
 	utilruntime.Must(v1beta1.AddToScheme(scheme))
@@ -58,11 +61,13 @@ func main() {
 	var metricsAddr string
 	var enableLeaderElection bool
 	var probeAddr string
+	var watchNamespace string
 	flag.StringVar(&metricsAddr, "metrics-bind-address", ":8082", "The address the metric endpoint binds to.")
 	flag.StringVar(&probeAddr, "health-probe-bind-address", ":8083", "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(&watchNamespace, "namespace", "", "Namespace that the controller watches to reconcile cluster-api objects. If unspecified, the controller watches for cluster-api objects across all namespaces.")
 	opts := zap.Options{
 		Development: true,
 	}
@@ -71,13 +76,18 @@ func main() {
 
 	ctrl.SetLogger(zap.New(zap.UseFlagOptions(&opts)))
 
+	if watchNamespace != "" {
+		setupLog.Info("Watching cluster-api objects only in namespace for reconciliation", "namespace", watchNamespace)
+	}
+
 	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), ctrl.Options{
 		Scheme:                 scheme,
 		MetricsBindAddress:     metricsAddr,
 		Port:                   9443,
 		HealthProbeBindAddress: probeAddr,
 		LeaderElection:         enableLeaderElection,
 		LeaderElectionID:       "microk8s-control-plane-manager-leader-election-capi",
+		Namespace:              watchNamespace,
 	})
 	if err != nil {
 		setupLog.Error(err, "unable to start manager")