next (v5.7.0; do not merge)

bootstrapper-maven-plugin/pom.xml

@@ -22,7 +22,7 @@
   <parent>
     <groupId>io.javaoperatorsdk</groupId>
     <artifactId>java-operator-sdk</artifactId>
-    <version>5.6.1-SNAPSHOT</version>
+    <version>999-SNAPSHOT</version>
   </parent>
 
   <artifactId>bootstrapper</artifactId>

caffeine-bounded-cache-support/pom.xml

@@ -21,7 +21,7 @@
   <parent>
     <groupId>io.javaoperatorsdk</groupId>
     <artifactId>java-operator-sdk</artifactId>
-    <version>5.6.1-SNAPSHOT</version>
+    <version>999-SNAPSHOT</version>
   </parent>
 
   <artifactId>caffeine-bounded-cache-support</artifactId>

docs/content/en/docs/documentation/dependent-resource-and-workflows/dependent-resources.md

@@ -531,6 +531,34 @@ samples [here](https://github.com/java-operator-sdk/java-operator-sdk/tree/main/
    in [related integration test](https://github.com/operator-framework/java-operator-sdk/blob/main/operator-framework/src/test/java/io/javaoperatorsdk/operator/workflow/orderedmanageddependent/ConfigMapDependentResource2.java)
    .
 
+### Adding Common Metadata to All Managed Resources (Desired State Aspects)
+
+Operators often need to mark every resource they manage in a uniform way, for example with a
+`app.kubernetes.io/managed-by` label, so that these resources can easily be identified, selected or
+garbage-collected later on. Instead of repeating that logic in every `desired()` implementation, a
+`DesiredStateAspect` can be registered once, at the operator level, and is then applied to the
+desired state of every Kubernetes dependent resource managed by the operator:
+
+```java
+Operator operator = new Operator(overrider -> overrider
+    .withDesiredStateAspects(List.of(
+        (desired, dependentResource, context) -> desired.getMetadata().getLabels()
+            .put("app.kubernetes.io/managed-by", "my-operator"))));
+```
+
+Aspects are applied, in registration order, right after the desired state has been computed and
+before the desired state is matched against the actual resource, created or updated. As a
+consequence, the metadata added by an aspect is part of the desired state proper: if it is removed
+from the actual resource, or if the aspect itself changes, the associated secondary resources are
+updated accordingly on the next reconciliation.
+
+Since the desired state is computed at most once per reconciliation and cached in the `Context`,
+aspects are called at most once per dependent resource and reconciliation. They are only called for
+dependent resources whose desired state is a `HasMetadata`, meaning that external (non-Kubernetes)
+dependent resources are left untouched. Implementations are expected to modify the provided desired
+state in place and need to be thread-safe as they can be called concurrently for different primary
+resources.
+
 ## "Read-only" Dependent Resources vs. Event Source
 
 See Integration test for a read-only

micrometer-support/pom.xml

@@ -21,7 +21,7 @@
   <parent>
     <groupId>io.javaoperatorsdk</groupId>
     <artifactId>java-operator-sdk</artifactId>
-    <version>5.6.1-SNAPSHOT</version>
+    <version>999-SNAPSHOT</version>
   </parent>
 
   <artifactId>micrometer-support</artifactId>

migration/pom.xml

@@ -21,7 +21,7 @@
   <parent>
     <groupId>io.javaoperatorsdk</groupId>
     <artifactId>java-operator-sdk</artifactId>
-    <version>5.6.1-SNAPSHOT</version>
+    <version>999-SNAPSHOT</version>
   </parent>
 
   <artifactId>migration</artifactId>

operator-framework-bom/pom.xml

@@ -21,7 +21,7 @@
 
   <groupId>io.javaoperatorsdk</groupId>
   <artifactId>operator-framework-bom</artifactId>
-  <version>5.6.1-SNAPSHOT</version>
+  <version>999-SNAPSHOT</version>
   <packaging>pom</packaging>
   <name>Operator SDK - Bill of Materials</name>
   <description>Java SDK for implementing Kubernetes operators</description>

operator-framework-core/pom.xml

@@ -21,7 +21,7 @@
   <parent>
     <groupId>io.javaoperatorsdk</groupId>
     <artifactId>java-operator-sdk</artifactId>
-    <version>5.6.1-SNAPSHOT</version>
+    <version>999-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
 

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

@@ -16,6 +16,7 @@
 package io.javaoperatorsdk.operator.api.config;
 
 import java.time.Duration;
+import java.util.List;
 import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.ExecutorService;
@@ -41,6 +42,7 @@
 import io.javaoperatorsdk.operator.api.reconciler.Experimental;
 import io.javaoperatorsdk.operator.api.reconciler.Reconciler;
 import io.javaoperatorsdk.operator.api.reconciler.dependent.DependentResourceFactory;
+import io.javaoperatorsdk.operator.api.reconciler.dependent.DesiredStateAspect;
 import io.javaoperatorsdk.operator.processing.dependent.kubernetes.KubernetesDependent;
 import io.javaoperatorsdk.operator.processing.dependent.kubernetes.KubernetesDependentResource;
 import io.javaoperatorsdk.operator.processing.dependent.kubernetes.KubernetesDependentResourceConfig;
@@ -539,4 +541,18 @@ default InformerPool informerPool() {
     pool.setConfigurationService(this);
     return pool;
   }
+
+  /**
+   * Retrieves the {@link DesiredStateAspect}s applied to the desired state of all the Kubernetes
+   * dependent resources managed by the operator. Aspects are applied in the order in which they are
+   * returned, right after the desired state has been computed, and are typically used to add common
+   * metadata (such as a label identifying the operator managing the resource) to all the resources
+   * the operator creates or updates.
+   *
+   * @return the list of aspects to apply to computed desired states, empty by default
+   * @since 5.6.0
+   */
+  default List<DesiredStateAspect> desiredStateAspects() {
+    return List.of();
+  }
 }

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

@@ -16,6 +16,8 @@
 package io.javaoperatorsdk.operator.api.config;
 
 import java.time.Duration;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.ExecutorService;
@@ -31,6 +33,7 @@
 import io.javaoperatorsdk.operator.api.monitoring.Metrics;
 import io.javaoperatorsdk.operator.api.reconciler.Experimental;
 import io.javaoperatorsdk.operator.api.reconciler.dependent.DependentResourceFactory;
+import io.javaoperatorsdk.operator.api.reconciler.dependent.DesiredStateAspect;
 import io.javaoperatorsdk.operator.processing.event.source.informer.pool.InformerPool;
 
 @SuppressWarnings({"unused", "UnusedReturnValue"})
@@ -59,6 +62,7 @@ public class ConfigurationServiceOverrider {
   private Boolean useSSAToPatchPrimaryResource;
   private Boolean cloneSecondaryResourcesWhenGettingFromCache;
   private InformerPool informerPool;
+  private List<DesiredStateAspect> desiredStateAspects;
 
   @SuppressWarnings("rawtypes")
   private DependentResourceFactory dependentResourceFactory;
@@ -229,6 +233,38 @@ public ConfigurationServiceOverrider withInformerPool(InformerPool informerPool)
     return this;
   }
 
+  /**
+   * Replaces the {@link DesiredStateAspect}s applied to the desired state of all the Kubernetes
+   * dependent resources managed by the operator by the specified ones.
+   *
+   * @param desiredStateAspects the aspects to apply, in the order in which they should be applied
+   * @return this {@link ConfigurationServiceOverrider} for chained customization
+   * @since 5.6.0
+   */
+  public ConfigurationServiceOverrider withDesiredStateAspects(
+      List<DesiredStateAspect> desiredStateAspects) {
+    this.desiredStateAspects = new ArrayList<>(desiredStateAspects);
+    return this;
+  }
+
+  /**
+   * Appends the specified {@link DesiredStateAspect}s to the already configured ones, which are the
+   * ones configured on the overridden {@link ConfigurationService} unless {@link
+   * #withDesiredStateAspects(List)} was called on this overrider first.
+   *
+   * @param desiredStateAspects the aspects to append, in the order in which they should be applied
+   * @return this {@link ConfigurationServiceOverrider} for chained customization
+   * @since 5.6.0
+   */
+  public ConfigurationServiceOverrider addDesiredStateAspects(
+      DesiredStateAspect... desiredStateAspects) {
+    if (this.desiredStateAspects == null) {
+      this.desiredStateAspects = new ArrayList<>(original.desiredStateAspects());
+    }
+    this.desiredStateAspects.addAll(List.of(desiredStateAspects));
+    return this;
+  }
+
   public ConfigurationService build() {
     return new BaseConfigurationService(original.getVersion(), cloner, client) {
       @Override
@@ -383,6 +419,12 @@ public synchronized InformerPool informerPool() {
         informerPool.setConfigurationService(this);
         return informerPool;
       }
+
+      @Override
+      public List<DesiredStateAspect> desiredStateAspects() {
+        return overriddenValueOrDefault(
+            desiredStateAspects, ConfigurationService::desiredStateAspects);
+      }
     };
   }
 }