Add metric for number of target namespace

internal/metrics/collector.go

@@ -31,7 +31,7 @@ type OctopusMetricsCollector struct {
 	scopesWithTenantsTotalDesc      *prometheus.Desc
 	scopesWithStepsTotalDesc        *prometheus.Desc
 	scopesWithSpacesTotalDesc       *prometheus.Desc
-	discoveredAgentsTotalDesc       *prometheus.Desc
+	targetNamespacesTotalDesc       *prometheus.Desc
 }
 
 // NewOctopusMetricsCollector creates a new instance of OctopusMetricsCollector
@@ -118,10 +118,10 @@ func NewOctopusMetricsCollector(cli client.Client, eng rules.Engine) *OctopusMet
 			nil,
 			nil,
 		),
-		discoveredAgentsTotalDesc: prometheus.NewDesc(
-			"octopus_discovered_agents_total",
-			"Number of discovered agents",
-			[]string{"agent_type"},
+		targetNamespacesTotalDesc: prometheus.NewDesc(
+			"octopus_target_namespaces_total",
+			"Number of target namespaces",
+			nil,
 			nil,
 		),
 	}
@@ -143,7 +143,7 @@ func (c *OctopusMetricsCollector) Describe(ch chan<- *prometheus.Desc) {
 	ch <- c.scopesWithTenantsTotalDesc
 	ch <- c.scopesWithStepsTotalDesc
 	ch <- c.scopesWithSpacesTotalDesc
-	ch <- c.discoveredAgentsTotalDesc
+	ch <- c.targetNamespacesTotalDesc
 }
 
 // Collect implements the prometheus.Collector interface
@@ -176,6 +176,8 @@ func (c *OctopusMetricsCollector) Collect(ch chan<- prometheus.Metric) {
 	if err := c.collectScopeMetricsFromResources(ctx, ch); err != nil {
 		logger.Error(err, "Failed to collect scope metrics from resources")
 	}
+
+	c.collectTargetNamespaceMetrics(ch)
 }
 
 // collectWSAMetrics collects WorkloadServiceAccount metrics
@@ -418,6 +420,18 @@ func (c *OctopusMetricsCollector) collectScopeMetricsFromResources(ctx context.C
 	return nil
 }
 
+func (c *OctopusMetricsCollector) collectTargetNamespaceMetrics(ch chan<- prometheus.Metric) {
+	targetNamespaces := c.engine.GetTargetNamespaces()
+	count := len(targetNamespaces)
+
+	metric := prometheus.MustNewConstMetric(
+		c.targetNamespacesTotalDesc,
+		prometheus.GaugeValue,
+		float64(count),
+	)
+	ch <- metric
+}
+
 func (c *OctopusMetricsCollector) TrackRequest(controllerType string, scopeMatched bool) {
 	IncRequestsTotal(controllerType, scopeMatched)
 }

internal/metrics/metrics.md

@@ -29,8 +29,8 @@ All metrics are prefixed with `octopus_` to allow easy filtering in Prometheus q
 - **`octopus_scopes_with_steps_total`**: Number of scopes with Step defined
 - **`octopus_scopes_with_spaces_total`**: Number of scopes with Space defined
 
-#### Agent Metrics
-- **`octopus_discovered_agents_total{agent_type}`**: Number of discovered agents by type
+#### Namespace Metrics
+- **`octopus_target_namespaces_total`**: Number of target namespaces
 
 ### Request Metrics (Counter)
 

internal/metrics/metrics_test.go

@@ -234,6 +234,9 @@ var _ = Describe("Metrics Test", func() {
 					},
 				)
 
+				// Set up mock expectations for GetTargetNamespaces
+				mockEngine.On("GetTargetNamespaces").Return([]string{"namespace1", "namespace2"})
+
 				// Create collector with mock engine
 				mockCollector := NewOctopusMetricsCollector(k8sClient, mockEngine)
 				Expect(mockCollector).NotTo(BeNil())
@@ -292,6 +295,9 @@ var _ = Describe("Metrics Test", func() {
 					},
 				)
 
+				// Set up mock expectations for GetTargetNamespaces
+				mockEngine.On("GetTargetNamespaces").Return([]string{"namespace1", "namespace2"})
+
 				// Set up mock expectations for other Get* methods that the collector will call
 				mockEngine.On("GetWorkloadServiceAccounts", mock.MatchedBy(func(ctx context.Context) bool { return true })).Return(
 					iter.Seq[*v1beta1.WorkloadServiceAccount](func(yield func(*v1beta1.WorkloadServiceAccount) bool) {}),

internal/rules/engine.go

@@ -384,6 +384,10 @@ func (i *InMemoryEngine) cleanupOrphanedResources(
 	return nil
 }
 
+func (i *InMemoryEngine) GetTargetNamespaces() []string {
+	return i.targetNamespaces
+}
+
 // reconcilePermissionsOnly performs fast path reconciliation when only permissions changed
 func (i *InMemoryEngine) reconcilePermissionsOnly(
 	ctx context.Context, resource WSAResource, scopeMap map[Scope]map[string]WSAResource,

internal/rules/namespace_discovery.go

@@ -11,6 +11,7 @@ import (
 
 type NamespaceDiscovery interface {
 	DiscoverTargetNamespaces(ctx context.Context, k8sClient client.Client) ([]string, error)
+	GetTargetNamespaces() []string
 }
 
 type NamespaceDiscoveryService struct {
@@ -56,3 +57,7 @@ func (nds NamespaceDiscoveryService) DiscoverTargetNamespaces(
 
 	return namespaces, nil
 }
+
+func (nds NamespaceDiscoveryService) GetTargetNamespaces() []string {
+	return []string{}
+}

internal/test/mocks/engine.go

@@ -116,6 +116,11 @@ func (m *MockEngine) DiscoverTargetNamespaces(ctx context.Context, k8sClient cli
 	return args.Get(0).([]string), args.Error(1)
 }
 
+func (m *MockEngine) GetTargetNamespaces() []string {
+	args := m.Called()
+	return args.Get(0).([]string)
+}
+
 func (m *MockEngine) GarbageCollectServiceAccounts(
 	ctx context.Context, expectedServiceAccounts *set.Set[string], targetNamespaces *set.Set[string],
 ) (ctrl.Result, error) {