global cache not used when watchNamespaces is empty in the helm values

CONTRIBUTING.md

@@ -96,7 +96,7 @@ And then handle it accordingly in your monitor's implementation.
 
 #### Examples
 
-In [endpointmonitor_types.go](./pkg/apis/endpointmonitor/v1alpha1/endpointmonitor_types.go)
+In [endpointmonitor_types.go](./api/v1alpha1/endpointmonitor_types.go)
 
 ```yaml
 // UptimeRobotConfig defines the configuration for UptimeRobot Monitor Provider

cmd/main.go

@@ -142,24 +142,17 @@ func main() {
 		Metrics: metricsServerOptions,
 	}
 
-	namespaces := []string{}
 	// Add support for MultiNamespace set in WATCH_NAMESPACE (e.g ns1,ns2)
 	// More Info: https://godoc.org/github.com/kubernetes-sigs/controller-runtime/pkg/cache#MultiNamespacedCacheBuilder
-	if strings.Contains(watchNamespace, ",") {
-		setupLog.Info("Manager will be watching namespace(s) %q", watchNamespace)
-		// configure cluster-scoped with MultiNamespacedCacheBuilder
-		//options.Namespace = ""
-		namespaces = strings.Split(watchNamespace, ",")
-	} else {
-		namespaces = []string{watchNamespace}
-	}
-
-	options.NewCache = func(config *rest.Config, opts cache.Options) (cache.Cache, error) {
-		opts.DefaultNamespaces = map[string]cache.Config{}
-		for _, ns := range namespaces {
-			opts.DefaultNamespaces[ns] = cache.Config{}
+	// Only restrict the cache when a non-empty WATCH_NAMESPACE is set. When empty, leave DefaultNamespaces nil
+	// so the manager uses a global (all-namespace) cache. Setting DefaultNamespaces = {"": {}} would trigger
+	// multiNamespaceCache whose List() does not fall back to the global informer for specific namespaces.
+	if defaultNamespaces := buildDefaultNamespaces(watchNamespace); defaultNamespaces != nil {
+		setupLog.Info("Manager will be watching namespace(s)", "namespaces", watchNamespace)
+		options.NewCache = func(config *rest.Config, opts cache.Options) (cache.Cache, error) {
+			opts.DefaultNamespaces = defaultNamespaces
+			return cache.New(config, opts)
 		}
-		return cache.New(config, opts)
 	}
 
 	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), options)
@@ -199,6 +192,26 @@ func main() {
 	}
 }
 
+// buildDefaultNamespaces returns the cache.Config map for the given comma-separated
+// watchNamespace value, or nil when watchNamespace is empty (cluster-scoped cache).
+func buildDefaultNamespaces(watchNamespace string) map[string]cache.Config {
+	if watchNamespace == "" {
+		return nil
+	}
+	result := map[string]cache.Config{}
+	for _, ns := range strings.Split(watchNamespace, ",") {
+		ns = strings.TrimSpace(ns)
+		if ns == "" {
+			continue
+		}
+		result[ns] = cache.Config{}
+	}
+	if len(result) == 0 {
+		return nil
+	}
+	return result
+}
+
 func getWatchNamespace() (string, error) {
 	// WatchNamespaceEnvVar is the constant for env variable WATCH_NAMESPACE
 	// which specifies the Namespace to watch.

cmd/main_test.go

@@ -0,0 +1,123 @@
+package main
+
+import (
+	"os"
+	"testing"
+)
+
+func TestBuildDefaultNamespaces(t *testing.T) {
+	tests := []struct {
+		name           string
+		watchNamespace string
+		wantNil        bool
+		wantKeys       []string
+	}{
+		{
+			name:           "empty string returns nil (cluster-scoped cache)",
+			watchNamespace: "",
+			wantNil:        true,
+		},
+		{
+			name:           "single namespace",
+			watchNamespace: "my-namespace",
+			wantKeys:       []string{"my-namespace"},
+		},
+		{
+			name:           "multiple namespaces",
+			watchNamespace: "ns1,ns2,ns3",
+			wantKeys:       []string{"ns1", "ns2", "ns3"},
+		},
+		{
+			name:           "namespaces with surrounding spaces are trimmed",
+			watchNamespace: "ns1, ns2 , ns3",
+			wantKeys:       []string{"ns1", "ns2", "ns3"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := buildDefaultNamespaces(tt.watchNamespace)
+
+			if tt.wantNil {
+				if got != nil {
+					t.Errorf("expected nil, got %v", got)
+				}
+				return
+			}
+
+			if got == nil {
+				t.Fatal("expected non-nil map, got nil")
+			}
+
+			if len(got) != len(tt.wantKeys) {
+				t.Errorf("expected %d namespaces, got %d: %v", len(tt.wantKeys), len(got), got)
+			}
+
+			for _, key := range tt.wantKeys {
+				if _, ok := got[key]; !ok {
+					t.Errorf("expected key %q in map, got %v", key, got)
+				}
+			}
+		})
+	}
+}
+
+func TestGetWatchNamespace(t *testing.T) {
+	tests := []struct {
+		name    string
+		envVal  string
+		envSet  bool
+		wantNS  string
+		wantErr bool
+	}{
+		{
+			name:    "env var not set returns error",
+			envSet:  false,
+			wantErr: true,
+		},
+		{
+			name:   "empty env var returns empty string (cluster-scoped)",
+			envSet: true,
+			envVal: "",
+			wantNS: "",
+		},
+		{
+			name:   "single namespace",
+			envSet: true,
+			envVal: "my-namespace",
+			wantNS: "my-namespace",
+		},
+		{
+			name:   "multiple namespaces passed through as-is",
+			envSet: true,
+			envVal: "ns1,ns2",
+			wantNS: "ns1,ns2",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			os.Unsetenv("WATCH_NAMESPACE")
+			if tt.envSet {
+				os.Setenv("WATCH_NAMESPACE", tt.envVal)
+				defer os.Unsetenv("WATCH_NAMESPACE")
+			}
+
+			got, err := getWatchNamespace()
+
+			if tt.wantErr {
+				if err == nil {
+					t.Error("expected error, got nil")
+				}
+				return
+			}
+
+			if err != nil {
+				t.Errorf("unexpected error: %v", err)
+			}
+			if got != tt.wantNS {
+				t.Errorf("expected %q, got %q", tt.wantNS, got)
+			}
+		})
+	}
+}