feat: option to limit CRs the operator watches

operator-framework-core/pom.xml

@@ -50,13 +50,14 @@
     </plugins>
   </build>
 
+
   <dependencies>
     <!-- We use the OpenShift client, because functionally it is a superset of the Kubernetes client -->
     <dependency>
       <groupId>io.fabric8</groupId>
       <artifactId>openshift-client</artifactId>
     </dependency>
-    
+
     <dependency>
       <groupId>org.slf4j</groupId>
       <artifactId>slf4j-api</artifactId>
@@ -97,5 +98,15 @@
       <artifactId>log4j-core</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>io.fabric8</groupId>
+      <artifactId>kubernetes-server-mock</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.awaitility</groupId>
+      <artifactId>awaitility</artifactId>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 </project>

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/Controller.java

@@ -40,4 +40,13 @@
    * @return the list of namespaces this controller monitors
    */
   String[] namespaces() default {};
+
+  /**
+   * Optional label selector used to identify the set of custom resources the controller will acc
+   * upon. The label selector can be made of multiple comma separated requirements that acts as a
+   * logical AND operator.
+   *
+   * @return the finalizer name
+   */
+  String labelSelector() default NULL;
 }

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/config/AbstractControllerConfiguration.java

@@ -15,6 +15,7 @@ public abstract class AbstractControllerConfiguration<R extends CustomResource>
   private final Set<String> namespaces;
   private final boolean watchAllNamespaces;
   private final RetryConfiguration retryConfiguration;
+  private final String labelSelector;
   private ConfigurationService service;
 
   public AbstractControllerConfiguration(
@@ -24,7 +25,8 @@ public AbstractControllerConfiguration(
       String finalizer,
       boolean generationAware,
       Set<String> namespaces,
-      RetryConfiguration retryConfiguration) {
+      RetryConfiguration retryConfiguration,
+      String labelSelector) {
     this.associatedControllerClassName = associatedControllerClassName;
     this.name = name;
     this.crdName = crdName;
@@ -37,6 +39,25 @@ public AbstractControllerConfiguration(
         retryConfiguration == null
             ? ControllerConfiguration.super.getRetryConfiguration()
             : retryConfiguration;
+    this.labelSelector = labelSelector;
+  }
+
+  /**
+   * @deprecated use
+   *             {@link #AbstractControllerConfiguration(String, String, String, String, boolean, Set, RetryConfiguration, String)}
+   *             instead
+   */
+  @Deprecated
+  public AbstractControllerConfiguration(
+      String associatedControllerClassName,
+      String name,
+      String crdName,
+      String finalizer,
+      boolean generationAware,
+      Set<String> namespaces,
+      RetryConfiguration retryConfiguration) {
+    this(associatedControllerClassName, name, crdName, finalizer, generationAware, namespaces,
+        retryConfiguration, null);
   }
 
   @Override
@@ -88,4 +109,9 @@ public ConfigurationService getConfigurationService() {
   public void setConfigurationService(ConfigurationService service) {
     this.service = service;
   }
+
+  @Override
+  public String getLabelSelector() {
+    return labelSelector;
+  }
 }

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/config/ControllerConfiguration.java

@@ -1,21 +1,46 @@
 package io.javaoperatorsdk.operator.api.config;
 
 import io.fabric8.kubernetes.client.CustomResource;
+import io.javaoperatorsdk.operator.ControllerUtils;
 import io.javaoperatorsdk.operator.api.Controller;
+import java.lang.reflect.ParameterizedType;
 import java.util.Collections;
 import java.util.Set;
 
 public interface ControllerConfiguration<R extends CustomResource> {
 
-  String getName();
+  default String getName() {
+    return ControllerUtils.getDefaultResourceControllerName(getAssociatedControllerClassName());
+  }
 
-  String getCRDName();
+  default String getCRDName() {
+    return CustomResource.getCRDName(getCustomResourceClass());
+  }
 
-  String getFinalizer();
+  default String getFinalizer() {
+    return ControllerUtils.getDefaultFinalizerName(getCRDName());
+  }
+
+  /**
+   * Retrieves the label selector that is used to filter which custom resources are actually watched
+   * by the associated controller. See
+   * https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/ for more details on
+   * syntax.
+   *
+   * @return the label selector filtering watched custom resources
+   */
+  default String getLabelSelector() {
+    return null;
+  }
 
-  boolean isGenerationAware();
+  default boolean isGenerationAware() {
+    return true;
+  }
 
-  Class<R> getCustomResourceClass();
+  default Class<R> getCustomResourceClass() {
+    ParameterizedType type = (ParameterizedType) getClass().getGenericInterfaces()[0];
+    return (Class<R>) type.getActualTypeArguments()[0];
+  }
 
   String getAssociatedControllerClassName();
 
@@ -67,7 +92,7 @@ default RetryConfiguration getRetryConfiguration() {
 
   ConfigurationService getConfigurationService();
 
-  void setConfigurationService(ConfigurationService service);
+  default void setConfigurationService(ConfigurationService service) {}
 
   default boolean useFinalizer() {
     return !Controller.NO_FINALIZER.equals(getFinalizer());

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/config/ControllerConfigurationOverrider.java

@@ -11,13 +11,15 @@ public class ControllerConfigurationOverrider<R extends CustomResource> {
   private boolean generationAware;
   private Set<String> namespaces;
   private RetryConfiguration retry;
+  private String labelSelector;
   private final ControllerConfiguration<R> original;
 
   private ControllerConfigurationOverrider(ControllerConfiguration<R> original) {
     finalizer = original.getFinalizer();
     generationAware = original.isGenerationAware();
     namespaces = new HashSet<>(original.getNamespaces());
     retry = original.getRetryConfiguration();
+    labelSelector = original.getLabelSelector();
     this.original = original;
   }
 
@@ -57,6 +59,11 @@ public ControllerConfigurationOverrider<R> withRetry(RetryConfiguration retry) {
     return this;
   }
 
+  public ControllerConfigurationOverrider<R> withLabelSelector(String labelSelector) {
+    this.labelSelector = labelSelector;
+    return this;
+  }
+
   public ControllerConfiguration<R> build() {
     return new AbstractControllerConfiguration<R>(
         original.getAssociatedControllerClassName(),
@@ -65,7 +72,8 @@ public ControllerConfiguration<R> build() {
         finalizer,
         generationAware,
         namespaces,
-        retry) {
+        retry,
+        labelSelector) {
       @Override
       public Class<R> getCustomResourceClass() {
         return original.getCustomResourceClass();

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/event/internal/CustomResourceEventSource.java

@@ -5,12 +5,14 @@
 import static io.javaoperatorsdk.operator.processing.KubernetesResourceUtils.getVersion;
 
 import io.fabric8.kubernetes.api.model.KubernetesResourceList;
+import io.fabric8.kubernetes.api.model.ListOptions;
 import io.fabric8.kubernetes.client.CustomResource;
 import io.fabric8.kubernetes.client.Watch;
 import io.fabric8.kubernetes.client.Watcher;
 import io.fabric8.kubernetes.client.WatcherException;
 import io.fabric8.kubernetes.client.dsl.MixedOperation;
 import io.fabric8.kubernetes.client.dsl.Resource;
+import io.fabric8.kubernetes.client.utils.Utils;
 import io.javaoperatorsdk.operator.api.config.ControllerConfiguration;
 import io.javaoperatorsdk.operator.processing.CustomResourceCache;
 import io.javaoperatorsdk.operator.processing.KubernetesResourceUtils;
@@ -33,6 +35,7 @@ public class CustomResourceEventSource<T extends CustomResource<?, ?>> extends A
   private final Set<String> targetNamespaces;
   private final boolean generationAware;
   private final String resourceFinalizer;
+  private final String labelSelector;
   private final Map<String, Long> lastGenerationProcessedSuccessfully = new ConcurrentHashMap<>();
   private final List<Watch> watches;
   private final String resClass;
@@ -46,6 +49,7 @@ public CustomResourceEventSource(
         configuration.getEffectiveNamespaces(),
         configuration.isGenerationAware(),
         configuration.getFinalizer(),
+        configuration.getLabelSelector(),
         configuration.getCustomResourceClass(),
         new CustomResourceCache(configuration.getConfigurationService().getObjectMapper()));
   }
@@ -55,12 +59,14 @@ public CustomResourceEventSource(
       Set<String> targetNamespaces,
       boolean generationAware,
       String resourceFinalizer,
+      String labelSelector,
       Class<T> resClass) {
     this(
         client,
         targetNamespaces,
         generationAware,
         resourceFinalizer,
+        labelSelector,
         resClass,
         new CustomResourceCache());
   }
@@ -70,27 +76,34 @@ public CustomResourceEventSource(
       Set<String> targetNamespaces,
       boolean generationAware,
       String resourceFinalizer,
+      String labelSelector,
       Class<T> resClass,
       CustomResourceCache customResourceCache) {
     this.client = client;
     this.targetNamespaces = targetNamespaces;
     this.generationAware = generationAware;
     this.resourceFinalizer = resourceFinalizer;
+    this.labelSelector = labelSelector;
     this.watches = new ArrayList<>();
     this.resClass = resClass.getName();
     this.customResourceCache = customResourceCache;
   }
 
   @Override
   public void start() {
+    var options = new ListOptions();
+    if (Utils.isNotNullOrEmpty(labelSelector)) {
+      options.setLabelSelector(labelSelector);
+    }
+
     if (ControllerConfiguration.allNamespacesWatched(targetNamespaces)) {
-      var w = client.inAnyNamespace().watch(this);
+      var w = client.inAnyNamespace().watch(options, this);
       watches.add(w);
       log.debug("Registered controller {} -> {} for any namespace", resClass, w);
     } else {
       targetNamespaces.forEach(
           ns -> {
-            var w = client.inNamespace(ns).watch(this);
+            var w = client.inNamespace(ns).watch(options, this);
             watches.add(w);
             log.debug("Registered controller {} -> {} for namespace: {}", resClass, w, ns);
           });

operator-framework-core/src/test/java/io/javaoperatorsdk/operator/api/config/ControllerConfigurationTest.java

@@ -0,0 +1,25 @@
+package io.javaoperatorsdk.operator.api.config;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import io.javaoperatorsdk.operator.sample.simple.TestCustomResource;
+import org.junit.jupiter.api.Test;
+
+class ControllerConfigurationTest {
+
+  @Test
+  void getCustomResourceClass() {
+    final ControllerConfiguration<TestCustomResource> conf = new ControllerConfiguration<>() {
+      @Override
+      public String getAssociatedControllerClassName() {
+        return null;
+      }
+
+      @Override
+      public ConfigurationService getConfigurationService() {
+        return null;
+      }
+    };
+    assertEquals(TestCustomResource.class, conf.getCustomResourceClass());
+  }
+}

operator-framework-core/src/test/java/io/javaoperatorsdk/operator/processing/event/internal/CustomResourceEventSourceTest.java

@@ -25,7 +25,8 @@ class CustomResourceEventSourceTest {
   EventHandler eventHandler = mock(EventHandler.class);
 
   private CustomResourceEventSource<TestCustomResource> customResourceEventSource =
-      new CustomResourceEventSource<>(client, null, true, FINALIZER, TestCustomResource.class);
+      new CustomResourceEventSource<>(
+          client, null, true, FINALIZER, null, TestCustomResource.class);
 
   @BeforeEach
   public void setup() {
@@ -72,7 +73,8 @@ public void normalExecutionIfGenerationChanges() {
   @Test
   public void handlesAllEventIfNotGenerationAware() {
     customResourceEventSource =
-        new CustomResourceEventSource<>(client, null, false, FINALIZER, TestCustomResource.class);
+        new CustomResourceEventSource<>(
+            client, null, false, FINALIZER, null, TestCustomResource.class);
     setup();
 
     TestCustomResource customResource1 = TestUtils.testCustomResource();