docs: migration to 4.4

docs/_data/sidebar.yml

@@ -9,7 +9,7 @@
     url: /docs/glossary
   - title: Features
     url: /docs/features
-  - title: Dependent Resource Feature
+  - title: Dependent Resources
     url: /docs/dependent-resources
   - title: Workflows
     url: /docs/workflows
@@ -26,4 +26,8 @@
   - title: Migrating from v2 to v3
     url: /docs/v3-migration
   - title: Migrating from v3 to v3.1
-    url: /docs/v3-1-migration
+    url: /docs/v3-1-migration
+  - title: Migrating from v4.2 to v4.3
+    url: /docs/v4-3-migration
+  - title: Migrating from v4.3 to v4.4
+    url: /docs/v4-4-migration

docs/documentation/v4-4-migration.md

@@ -0,0 +1,76 @@
+---
+title: Migrating from v4.3 to v4.4
+description: Migrating from v4.3 to v4.4
+layout: docs
+permalink: /docs/v4-4-migration
+---
+
+# Migrating from v4.3 to v4.4
+
+## API changes
+
+### ConfigurationService
+
+We have simplified how to deal with the Kubernetes client. Previous versions provided direct
+access to underlying aspects of the client's configuration or serialization mechanism. However,
+the link between these aspects wasn't as explicit as it should have been. Moreover, the Fabric8
+client framework has also revised their serialization architecture in the 6.7 version (see [this
+fabric8 pull request](https://github.com/fabric8io/kubernetes-client/pull/4662) for a discussion of
+that change), moving from statically configured serialization to a per-client configuration
+(though it's still possible to share serialization mechanism between client instances). As a
+consequence, we made the following changes to the `ConfigurationService` API:
+
+- Replaced `getClientConfiguration` and `getObjectMapper` methods by a new `getKubernetesClient`
+  method: instead of providing the configuration and mapper, you now provide a client instance
+  configured according to your needs and the SDK will extract the needed information from it
+
+If you had previously configured a custom configuration or `ObjectMapper`, it is now recommended 
+that you do so when creating your client instance, as follows, usually using 
+`ConfigurationServiceOverrider.withKubernetesClient`:
+
+```java
+
+class Example {
+
+  public static void main(String[] args) {
+    Config config; // your configuration
+    ObjectMapper mapper; // your mapper
+    final var operator = new Operator(overrider -> overrider.withKubernetesClient(
+            new KubernetesClientBuilder()
+                    .withConfig(config)
+                    .withKubernetesSerialization(new KubernetesSerialization(mapper, true))
+                    .build()
+        ));
+  }
+}
+```
+
+Consequently, it is now recommended to get the client instance from the `ConfigurationService`.
+
+### Operator
+
+It is now recommended to configure your Operator instance by using a 
+`ConfigurationServiceOverrider` when creating it. This allows you to change the default 
+configuration values as needed. In particular, instead of passing a Kubernetes client instance 
+explicitly to the Operator constructor, it is now recommended to provide that value using 
+`ConfigurationServiceOverrider.withKubernetesClient` as shown above.
+
+## Using Server-Side Apply in Dependent Resources
+
+From this version by
+default [Dependent Resources](https://javaoperatorsdk.io/docs/dependent-resources) use
+[Server Side Apply (SSA)](https://kubernetes.io/docs/reference/using-api/server-side-apply/) to
+create and
+update Kubernetes resources. A
+new [default matching](https://github.com/java-operator-sdk/java-operator-sdk/blob/e95f9c8a8b8a8561c9a735e60fc5d82b7758df8e/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/dependent/kubernetes/KubernetesDependentResource.java#L163-L163)
+algorithm is provided for `KubernetesDependentResource` that is based on `managedFields` of SSA. For
+details
+see [SSABasedGenericKubernetesResourceMatcher](https://github.com/java-operator-sdk/java-operator-sdk/blob/e95f9c8a8b8a8561c9a735e60fc5d82b7758df8e/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/dependent/kubernetes/SSABasedGenericKubernetesResourceMatcher.java)
+
+Since those features are hard to completely test, we provided feature flags to revert to the
+legacy behavior if needed,
+see those
+in [ConfigurationService](https://github.com/java-operator-sdk/java-operator-sdk/blob/e95f9c8a8b8a8561c9a735e60fc5d82b7758df8e/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/config/ConfigurationService.java#L268-L289)
+
+Note that it is possible to override the related methods/behavior on class level when extending
+the `KubernetesDependentResource`.

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

@@ -67,16 +67,13 @@ public Operator(Consumer<ConfigurationServiceOverrider> overrider) {
   }
 
   /**
-   * Note that Operator by default closes the client on stop, this can be changed using
-   * {@link ConfigurationService}
-   *
    * @param client client to use to all Kubernetes related operations
    * @param overrider a {@link ConfigurationServiceOverrider} consumer used to override the default
    *        {@link ConfigurationService} values
    * @deprecated Use {@link Operator#Operator(Consumer)} instead, passing your custom client with
    *             {@link ConfigurationServiceOverrider#withKubernetesClient(KubernetesClient)}
    */
-  @Deprecated
+  @Deprecated(since = "4.4.0")
   public Operator(KubernetesClient client, Consumer<ConfigurationServiceOverrider> overrider) {
     this(initConfigurationService(client, overrider));
   }

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

@@ -42,9 +42,12 @@ public interface ConfigurationService {
 
 
   /**
-   * Used to clone custom resources. It is strongly suggested that implementors override this method
-   * since the default implementation creates a new {@link Cloner} instance each time this method is
-   * called.
+   * Used to clone custom resources.
+   *
+   * <p>
+   * <em>NOTE:</em> It is strongly suggested that implementors override this method since the
+   * default implementation creates a new {@link Cloner} instance each time this method is called.
+   * </p>
    *
    * @return the configured {@link Cloner}
    */
@@ -57,6 +60,32 @@ public <R extends HasMetadata> R clone(R object) {
     };
   }
 
+  /**
+   * Provides the fully configured {@link KubernetesClient} to use for controllers to the target
+   * cluster. Note that this client only needs to be able to connect to the cluster, the SDK will
+   * take care of creating the required connections to watch the target resources (in particular,
+   * you do not need to worry about setting the namespace information in most cases).
+   *
+   * <p>
+   * Previous versions of this class provided direct access to the serialization mechanism (via
+   * {@link com.fasterxml.jackson.databind.ObjectMapper}) or the client's configuration. This was
+   * somewhat confusing, in particular with respect to changes made in the Fabric8 client
+   * serialization architecture made in 6.7. The proper way to configure these aspects is now to
+   * configure the Kubernetes client accordingly and the SDK will extract the information it needs
+   * from this instance. The recommended way to do so is to create your operator with
+   * {@link io.javaoperatorsdk.operator.Operator#Operator(Consumer)}, passing your custom instance
+   * with {@link ConfigurationServiceOverrider#withKubernetesClient(KubernetesClient)}.
+   * </p>
+   *
+   * <p>
+   * <em>NOTE:</em> It is strongly suggested that implementors override this method since the
+   * default implementation creates a new {@link KubernetesClient} instance each time this method is
+   * called.
+   * </p>
+   *
+   * @return the configured {@link KubernetesClient}
+   * @since 4.4.0
+   */
   default KubernetesClient getKubernetesClient() {
     return new KubernetesClientBuilder()
         .withConfig(new ConfigBuilder(Config.autoConfigure(null))
@@ -242,6 +271,25 @@ default ResourceClassResolver getResourceClassResolver() {
     return new DefaultResourceClassResolver();
   }
 
+  /**
+   * Creates a new {@link ConfigurationService} instance used to configure an
+   * {@link io.javaoperatorsdk.operator.Operator} instance, starting from the specified base
+   * configuration and overriding specific aspects according to the provided
+   * {@link ConfigurationServiceOverrider} instance.
+   *
+   * <p>
+   * <em>NOTE:</em> This overriding mechanism should only be used <strong>before</strong> creating
+   * your Operator instance as the configuration service is set at creation time and cannot be
+   * subsequently changed. As a result, overriding values this way after the Operator has been
+   * configured will not take effect.
+   * </p>
+   *
+   * @param baseConfiguration the {@link ConfigurationService} to start from
+   * @param overrider the {@link ConfigurationServiceOverrider} used to change the values provided
+   *        by the base configuration
+   * @return a new {@link ConfigurationService} starting from the configuration provided as base but
+   *         with overridden values.
+   */
   static ConfigurationService newOverriddenConfigurationService(
       ConfigurationService baseConfiguration,
       Consumer<ConfigurationServiceOverrider> overrider) {
@@ -253,6 +301,25 @@ static ConfigurationService newOverriddenConfigurationService(
     return baseConfiguration;
   }
 
+  /**
+   * Creates a new {@link ConfigurationService} instance used to configure an
+   * {@link io.javaoperatorsdk.operator.Operator} instance, starting from the default configuration
+   * and overriding specific aspects according to the provided {@link ConfigurationServiceOverrider}
+   * instance.
+   *
+   * <p>
+   * <em>NOTE:</em> This overriding mechanism should only be used <strong>before</strong> creating
+   * your Operator instance as the configuration service is set at creation time and cannot be
+   * subsequently changed. As a result, overriding values this way after the Operator has been
+   * configured will not take effect.
+   * </p>
+   *
+   * @param overrider the {@link ConfigurationServiceOverrider} used to change the values provided
+   *        by the default configuration
+   * @return a new {@link ConfigurationService} overriding the default values with the ones provided
+   *         by the specified {@link ConfigurationServiceOverrider}
+   * @since 4.4.0
+   */
   static ConfigurationService newOverriddenConfigurationService(
       Consumer<ConfigurationServiceOverrider> overrider) {
     return newOverriddenConfigurationService(new BaseConfigurationService(), overrider);
@@ -269,6 +336,8 @@ default ExecutorServiceManager getExecutorServiceManager() {
    * <a href="https://kubernetes.io/docs/reference/using-api/server-side-apply/">Server-Side
    * Apply</a> (SSA) by default. Note that the legacy approach, and this setting, might be removed
    * in the future.
+   *
+   * @since 4.4.0
    */
   default boolean ssaBasedCreateUpdateForDependentResources() {
     return true;
@@ -280,6 +349,8 @@ default boolean ssaBasedCreateUpdateForDependentResources() {
    * Dependent Resources which is quite complex. As a consequence, we introduced this setting to
    * allow folks to revert to the previous matching algorithm if needed. Note, however, that the
    * legacy algorithm, and this setting, might be removed in the future.
+   *
+   * @since 4.4.0
    */
   default boolean ssaBasedDefaultMatchingForDependentResources() {
     return true;

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

@@ -105,6 +105,13 @@ public ConfigurationServiceOverrider withWorkflowExecutorService(
     return this;
   }
 
+  /**
+   * Replaces the default {@link KubernetesClient} instance by the specified one. This is the
+   * preferred mechanism to configure which client will be used to access the cluster.
+   *
+   * @param client the fully configured client to use for cluster access
+   * @return this {@link ConfigurationServiceOverrider} for chained customization
+   */
   public ConfigurationServiceOverrider withKubernetesClient(KubernetesClient client) {
     this.client = client;
     return this;