Add namespace-level metrics

Author: rjeberhard

operator/src/main/java/oracle/kubernetes/operator/NamespaceCollector.java

@@ -0,0 +1,43 @@
+// Copyright (c) 2025, Oracle and/or its affiliates.
+// Licensed under the Universal Permissive License v 1.0 as shown at https://oss.oracle.com/licenses/upl.
+
+package oracle.kubernetes.operator;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+
+import io.prometheus.client.Collector;
+import io.prometheus.client.GaugeMetricFamily;
+import oracle.kubernetes.operator.helpers.DomainPresenceInfo;
+
+public class NamespaceCollector extends Collector {
+  private static final String WKO_NAMESPACE_COUNT = "wko_namespace_count";
+  private static final String WKO_DOMAIN_COUNT = "wko_domain_count";
+
+  private final MainDelegate mainDelegate;
+
+  public NamespaceCollector(MainDelegate mainDelegate) {
+    this.mainDelegate = mainDelegate;
+  }
+
+  @Override
+  public List<MetricFamilySamples> collect() {
+    List<MetricFamilySamples> mfs = new ArrayList<>();
+    Set<String> namespaces = mainDelegate.getDomainNamespaces().getNamespaces();
+    mfs.add(new GaugeMetricFamily(WKO_NAMESPACE_COUNT, "Count of managed namespaces", namespaces.size()));
+    Map<String, Map<String, DomainPresenceInfo>> dps = mainDelegate.getDomainProcessor().getDomainPresenceInfoMap();
+    GaugeMetricFamily domains = new GaugeMetricFamily(
+        WKO_DOMAIN_COUNT, "Count of WebLogic domains", Collections.singletonList("namespace"));
+    mfs.add(domains);
+    for (String ns : namespaces) {
+      Map<String, DomainPresenceInfo> dp = dps.get(ns);
+      int size = Optional.ofNullable(dp).map(Map::size).orElse(0);
+      domains.addMetric(Collections.singletonList(ns), size);
+    }
+    return mfs;
+  }
+}

operator/src/main/java/oracle/kubernetes/operator/OperatorMain.java

@@ -297,6 +297,7 @@ public NextAction onSuccess(Packet packet, CallResponse<V1NamespaceList> callRes
 
   void completeBegin() {
     try {
+      new NamespaceCollector(mainDelegate).register();
       startMetricsServer(container);
       startRestServer(container);