adding a watch-namespace option in order to only watch one namespace if set

Signed-off-by: augusto.ribeiro <augusto.ribeiro@cloudkitchens.com>

Author: augusto.ribeiro

internal/cmd/operator/main.go

@@ -103,5 +103,12 @@ func NewCmd() *cobra.Command {
 
 	_ = viper.BindEnv("sidecar-image", "SIDECAR_IMAGE")
 
+	cmd.Flags().String(
+		"watch-namespace",
+		"",
+		"The namespace to watch for CloudNativePG clusters. If empty, all namespaces will be watched.",
+	)
+	_ = viper.BindPFlag("watch-namespace", cmd.Flags().Lookup("watch-namespace"))
+
 	return cmd
 }

internal/cnpgi/operator/manager.go

@@ -31,6 +31,7 @@ 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/metrics/filters"
 	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
@@ -102,6 +103,14 @@ func Start(ctx context.Context) error {
 		metricsServerOptions.FilterProvider = filters.WithAuthenticationAndAuthorization
 	}
 
+	var cacheOptions cache.Options
+	if viper.GetString("watch-namespace") != "" {
+		setupLog.Info("Watching a single namespace", "namespace", viper.GetString("watch-namespace"))
+		cacheOptions = cache.Options{
+			DefaultNamespaces: map[string]cache.Config{viper.GetString("watch-namespace"): {}},
+		}
+	}
+
 	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), ctrl.Options{
 		Scheme:                 scheme,
 		Metrics:                metricsServerOptions,
@@ -120,6 +129,7 @@ func Start(ctx context.Context) error {
 		// 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,
+		Cache:                         cacheOptions,
 	})
 	if err != nil {
 		setupLog.Error(err, "unable to start manager")