Separate interface for cleanup part of reconciler and Dependent Resources

docs/documentation/features.md

@@ -37,9 +37,13 @@ execution.
 [Kubernetes finalizers](https://kubernetes.io/docs/concepts/overview/working-with-objects/finalizers/)
 make sure that a reconciliation happens when a custom resource is instructed to be deleted. Typical case when it's
 useful, when an operator is down (pod not running). Without a finalizer the reconciliation - thus the cleanup -
-i.e. [`Reconciler.cleanup(...)`](https://github.com/java-operator-sdk/java-operator-sdk/blob/b91221bb54af19761a617bf18eef381e8ceb3b4c/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/Reconciler.java#L31)
+i.e. [`Cleaner.cleanup(...)`](https://github.com/java-operator-sdk/java-operator-sdk/blob/b82c1f106968cb3eb18835c5e9cd1e4d5c40362e/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/Cleaner.java#L28-L28)
 would not happen if a custom resource is deleted.
 
+To use finalizers the reconciler have to implement [`Cleaner<P>`](https://github.com/java-operator-sdk/java-operator-sdk/blob/b82c1f106968cb3eb18835c5e9cd1e4d5c40362e/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/Cleaner.java) interface.
+In other words, finalizer is added if the `Reconciler` implements `Cleaner` interface. If not, no
+finalizer is added and/or removed.
+
 Finalizers are automatically added by the framework as the first step, thus after a custom resource is created, but
 before the first reconciliation. The finalizer is added via a separate Kubernetes API call. As a result of this update,
 the finalizer will be present. The subsequent event will be received, which will trigger the first reconciliation.
@@ -50,7 +54,6 @@ in some specific corner cases, when there would be a long waiting period for som
 
 The name of the finalizers can be specified, in case it is not, a name will be generated.
 
-Automatic finalizer handling can be turned off, so when configured no finalizer will be added or removed.  
 See [`@ControllerConfiguration`](https://github.com/java-operator-sdk/java-operator-sdk/blob/main/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/ControllerConfiguration.java)
 annotation for more details.
 
@@ -66,7 +69,7 @@ When automatic finalizer handling is turned off, the `Reconciler.cleanup(...)` m
 case when a delete event received. So it does not make sense to implement this method and turn off finalizer at the same
 time.
 
-## The `reconcile` and `cleanup` Methods of [`Reconciler`](https://github.com/java-operator-sdk/java-operator-sdk/blob/main/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/Reconciler.java)
+## The `reconcile` and [`cleanup`](https://github.com/java-operator-sdk/java-operator-sdk/blob/b82c1f106968cb3eb18835c5e9cd1e4d5c40362e/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/Cleaner.java) Methods on a [`Reconciler`](https://github.com/java-operator-sdk/java-operator-sdk/blob/main/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/Reconciler.java)
 
 The lifecycle of a custom resource can be clearly separated into two phases from the perspective of an operator. When a
 custom resource is created or update, or on the other hand when the custom resource is deleted - or rather marked for
@@ -75,9 +78,8 @@ deletion in case a finalizer is used.
 This separation-related logic is automatically handled by the framework. The framework will always call `reconcile`
 method, unless the custom resource is
 [marked from deletion](https://kubernetes.io/docs/concepts/overview/working-with-objects/finalizers/#how-finalizers-work)
-. From the point when the custom resource is marked from deletion, only the `cleanup` method is called.
-
-If there is **no finalizer** in place (see Finalizer Support section), the `cleanup` method is **not called**.
+. From the point when the custom resource is marked from deletion, only the `cleanup` method is called, of course 
+only if the reconciler implements the `Cleaner` interface.
 
 ### Using [`UpdateControl`](https://github.com/java-operator-sdk/java-operator-sdk/blob/main/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/UpdateControl.java) and [`DeleteControl`](https://github.com/java-operator-sdk/java-operator-sdk/blob/main/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/DeleteControl.java)
 

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/ReconcilerUtils.java

@@ -42,7 +42,7 @@ public void setApiVersion(String s) {
         throw new UnsupportedOperationException();
       }
     };
-    return Constants.NO_FINALIZER.equals(finalizer) || validator.isFinalizerValid(finalizer);
+    return validator.isFinalizerValid(finalizer);
   }
 
   public static String getResourceTypeNameWithVersion(Class<? extends HasMetadata> resourceClass) {

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

@@ -39,7 +39,7 @@ public String getName() {
   }
 
   @Override
-  public String getFinalizer() {
+  public String getFinalizerName() {
     if (annotation == null || annotation.finalizerName().isBlank()) {
       return ReconcilerUtils.getDefaultFinalizerName(getResourceClass());
     } else {

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

@@ -8,7 +8,6 @@
 import io.fabric8.kubernetes.api.model.HasMetadata;
 import io.javaoperatorsdk.operator.ReconcilerUtils;
 import io.javaoperatorsdk.operator.api.config.dependent.DependentResourceSpec;
-import io.javaoperatorsdk.operator.api.reconciler.Constants;
 import io.javaoperatorsdk.operator.processing.event.source.controller.ResourceEventFilter;
 import io.javaoperatorsdk.operator.processing.event.source.controller.ResourceEventFilters;
 
@@ -18,7 +17,7 @@ default String getName() {
     return ReconcilerUtils.getDefaultReconcilerName(getAssociatedReconcilerClassName());
   }
 
-  default String getFinalizer() {
+  default String getFinalizerName() {
     return ReconcilerUtils.getDefaultFinalizerName(getResourceClass());
   }
 
@@ -32,10 +31,6 @@ default RetryConfiguration getRetryConfiguration() {
     return RetryConfiguration.DEFAULT;
   }
 
-  default boolean useFinalizer() {
-    return !Constants.NO_FINALIZER.equals(getFinalizer());
-  }
-
   /**
    * Allow controllers to filter events before they are passed to the
    * {@link io.javaoperatorsdk.operator.processing.event.EventHandler}.

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

@@ -25,7 +25,7 @@ public class ControllerConfigurationOverrider<R extends HasMetadata> {
   private final List<DependentResourceSpec<?, ?>> dependentResourceSpecs;
 
   private ControllerConfigurationOverrider(ControllerConfiguration<R> original) {
-    finalizer = original.getFinalizer();
+    finalizer = original.getFinalizerName();
     generationAware = original.isGenerationAware();
     namespaces = new HashSet<>(original.getNamespaces());
     retry = original.getRetryConfiguration();

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

@@ -66,7 +66,7 @@ public String getResourceTypeName() {
   }
 
   @Override
-  public String getFinalizer() {
+  public String getFinalizerName() {
     return finalizer;
   }
 

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

@@ -0,0 +1,30 @@
+package io.javaoperatorsdk.operator.api.reconciler;
+
+import io.fabric8.kubernetes.api.model.HasMetadata;
+
+public interface Cleaner<P extends HasMetadata> {
+
+  /**
+   * Note that this method turns on automatic finalizer usage.
+   *
+   * The implementation should delete the associated component(s). This method is called when an
+   * object is marked for deletion. After it's executed the custom resource finalizer is
+   * automatically removed by the framework; unless the return value is
+   * {@link DeleteControl#noFinalizerRemoval()}, which indicates that the controller has determined
+   * that the resource should not be deleted yet. This is usually a corner case, when a cleanup is
+   * tried again eventually.
+   *
+   * <p>
+   * It's important for implementations of this method to be idempotent, since it can be called
+   * several times.
+   *
+   * @param resource the resource that is marked for deletion
+   * @param context the context with which the operation is executed
+   * @return {@link DeleteControl#defaultDelete()} - so the finalizer is automatically removed after
+   *         the call. {@link DeleteControl#noFinalizerRemoval()} if you don't want to remove the
+   *         finalizer to indicate that the resource should not be deleted after all, in which case
+   *         the controller should restore the resource's state appropriately.
+   */
+  DeleteControl cleanup(P resource, Context<P> context);
+
+}

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

@@ -4,7 +4,6 @@ public final class Constants {
 
   public static final String EMPTY_STRING = "";
   public static final String WATCH_CURRENT_NAMESPACE = "JOSDK_WATCH_CURRENT";
-  public static final String NO_FINALIZER = "JOSDK_NO_FINALIZER";
   public static final long NO_RECONCILIATION_MAX_INTERVAL = -1L;
 
   private Constants() {}

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

@@ -4,7 +4,7 @@
 
 import io.fabric8.kubernetes.api.model.HasMetadata;
 import io.javaoperatorsdk.operator.api.config.ControllerConfiguration;
-import io.javaoperatorsdk.operator.api.reconciler.dependent.ManagedDependentResourceContext;
+import io.javaoperatorsdk.operator.api.reconciler.dependent.managed.ManagedDependentResourceContext;
 
 public interface Context<P extends HasMetadata> {
 

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

@@ -15,9 +15,10 @@
   String name() default Constants.EMPTY_STRING;
 
   /**
-   * Optional finalizer name, if it is not provided, one will be automatically generated. If the
-   * provided value is the value specified by {@link Constants#NO_FINALIZER}, then no finalizer will
-   * be added to custom resources.
+   * Optional finalizer name, if it is not provided, one will be automatically generated. Note that
+   * finalizers are only added when Reconciler implement {@link Cleaner} interface, or at least one
+   * managed dependent resource implement
+   * {@link io.javaoperatorsdk.operator.api.reconciler.dependent.Deleter} interface.
    *
    * @return the finalizer name
    */

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

@@ -4,7 +4,7 @@
 
 import io.fabric8.kubernetes.api.model.HasMetadata;
 import io.javaoperatorsdk.operator.api.config.ControllerConfiguration;
-import io.javaoperatorsdk.operator.api.reconciler.dependent.ManagedDependentResourceContext;
+import io.javaoperatorsdk.operator.api.reconciler.dependent.managed.ManagedDependentResourceContext;
 import io.javaoperatorsdk.operator.processing.Controller;
 
 public class DefaultContext<P extends HasMetadata> implements Context<P> {

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

@@ -15,29 +15,4 @@ public interface Reconciler<R extends HasMetadata> {
    */
   UpdateControl<R> reconcile(R resource, Context<R> context) throws Exception;
 
-  /**
-   * Note that this method is used in combination with finalizers. If automatic finalizer handling
-   * is turned off for the controller, this method is not called.
-   *
-   * The implementation should delete the associated component(s). This method is called when an
-   * object is marked for deletion. After it's executed the custom resource finalizer is
-   * automatically removed by the framework; unless the return value is
-   * {@link DeleteControl#noFinalizerRemoval()}, which indicates that the controller has determined
-   * that the resource should not be deleted yet. This is usually a corner case, when a cleanup is
-   * tried again eventually.
-   *
-   * <p>
-   * It's important for implementations of this method to be idempotent, since it can be called
-   * several times.
-   *
-   * @param resource the resource that is marked for deletion
-   * @param context the context with which the operation is executed
-   * @return {@link DeleteControl#defaultDelete()} - so the finalizer is automatically removed after
-   *         the call. {@link DeleteControl#noFinalizerRemoval()} if you don't want to remove the
-   *         finalizer to indicate that the resource should not be deleted after all, in which case
-   *         the controller should restore the resource's state appropriately.
-   */
-  default DeleteControl cleanup(R resource, Context<R> context) {
-    return DeleteControl.defaultDelete();
-  }
 }

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/dependent/Deleter.java

@@ -3,6 +3,12 @@
 import io.fabric8.kubernetes.api.model.HasMetadata;
 import io.javaoperatorsdk.operator.api.reconciler.Context;
 
+/**
+ * DependentResource can implement this interface to denote it requires explicit logic to clean up
+ * resources.
+ *
+ * @param <P> primary resource type
+ */
 @FunctionalInterface
 public interface Deleter<P extends HasMetadata> {
   void delete(P primary, Context<P> context);

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/dependent/DependentResource.java

@@ -8,7 +8,5 @@
 public interface DependentResource<R, P extends HasMetadata> {
   ReconcileResult<R> reconcile(P primary, Context<P> context);
 
-  default void cleanup(P primary, Context<P> context) {}
-
   Optional<R> getResource(P primaryResource);
 }

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/dependent/ReconcileResult.java

@@ -4,8 +4,8 @@
 
 public class ReconcileResult<R> {
 
-  private R resource;
-  private Operation operation;
+  private final R resource;
+  private final Operation operation;
 
   public static <T> ReconcileResult<T> resourceCreated(T resource) {
     return new ReconcileResult<>(resource, Operation.CREATED);

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/dependent/DependentResourceConfigurator.java → operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/dependent/managed/DependentResourceConfigurator.java

@@ -1,4 +1,4 @@
-package io.javaoperatorsdk.operator.api.reconciler.dependent;
+package io.javaoperatorsdk.operator.api.reconciler.dependent.managed;
 
 public interface DependentResourceConfigurator<C> {
   void configureWith(C config);

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/dependent/KubernetesClientAware.java → operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/dependent/managed/KubernetesClientAware.java

@@ -1,4 +1,4 @@
-package io.javaoperatorsdk.operator.api.reconciler.dependent;
+package io.javaoperatorsdk.operator.api.reconciler.dependent.managed;
 
 import io.fabric8.kubernetes.client.KubernetesClient;
 

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/dependent/ManagedDependentResourceContext.java → operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/dependent/managed/ManagedDependentResourceContext.java

@@ -1,4 +1,4 @@
-package io.javaoperatorsdk.operator.api.reconciler.dependent;
+package io.javaoperatorsdk.operator.api.reconciler.dependent.managed;
 
 import java.util.Collections;
 import java.util.List;
@@ -7,6 +7,7 @@
 import java.util.stream.Collectors;
 
 import io.javaoperatorsdk.operator.OperatorException;
+import io.javaoperatorsdk.operator.api.reconciler.dependent.DependentResource;
 
 /**
  * Contextual information related to {@link DependentResource} either to retrieve the actual