Improvements (#569)

* feat: add Mappers class to provide convenient mapper implementations

* feat: add getAssociated method on InformerEventSource

Actually not sure if this makes sense: could there be cases where a
given primary resource maps to several secondary resources?

* refactor: use Function instead of dedicated classes. Clearer?

Author: metacosm

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

@@ -1,46 +1,57 @@
 package io.javaoperatorsdk.operator.processing.event.internal;
 
 import java.io.IOException;
-import java.util.List;
+import java.util.Objects;
+import java.util.Set;
+import java.util.function.Function;
 
 import io.fabric8.kubernetes.api.model.HasMetadata;
 import io.fabric8.kubernetes.client.KubernetesClient;
 import io.fabric8.kubernetes.client.informers.ResourceEventHandler;
 import io.fabric8.kubernetes.client.informers.SharedInformer;
+import io.fabric8.kubernetes.client.informers.cache.Cache;
 import io.fabric8.kubernetes.client.informers.cache.Store;
 import io.javaoperatorsdk.operator.processing.event.AbstractEventSource;
 
 public class InformerEventSource<T extends HasMetadata> extends AbstractEventSource {
 
   private final SharedInformer<T> sharedInformer;
-  private final ResourceToRelatedCustomResourceUIDMapper<T> mapper;
+  private final Function<T, Set<String>> resourceToUIDs;
+  private final Function<HasMetadata, T> associatedWith;
   private final boolean skipUpdateEventPropagationIfNoChange;
 
   public InformerEventSource(SharedInformer<T> sharedInformer,
-      ResourceToRelatedCustomResourceUIDMapper<T> mapper) {
-    this(sharedInformer, mapper, true);
+      Function<T, Set<String>> resourceToUIDs) {
+    this(sharedInformer, resourceToUIDs, null, true);
   }
 
-  InformerEventSource(KubernetesClient client, Class<T> type,
-      ResourceToRelatedCustomResourceUIDMapper<T> mapper) {
-    this(client, type, mapper, false);
+  public InformerEventSource(KubernetesClient client, Class<T> type,
+      Function<T, Set<String>> resourceToUIDs) {
+    this(client, type, resourceToUIDs, false);
   }
 
   InformerEventSource(KubernetesClient client, Class<T> type,
-      ResourceToRelatedCustomResourceUIDMapper<T> mapper,
+      Function<T, Set<String>> resourceToUIDs,
       boolean skipUpdateEventPropagationIfNoChange) {
-    this(client.informers().sharedIndexInformerFor(type, 0), mapper,
+    this(client.informers().sharedIndexInformerFor(type, 0), resourceToUIDs, null,
         skipUpdateEventPropagationIfNoChange);
   }
 
   public InformerEventSource(SharedInformer<T> sharedInformer,
-      ResourceToRelatedCustomResourceUIDMapper<T> mapper,
+      Function<T, Set<String>> resourceToUIDs,
+      Function<HasMetadata, T> associatedWith,
       boolean skipUpdateEventPropagationIfNoChange) {
     this.sharedInformer = sharedInformer;
-    this.mapper = mapper;
+    this.resourceToUIDs = resourceToUIDs;
     this.skipUpdateEventPropagationIfNoChange = skipUpdateEventPropagationIfNoChange;
 
-    sharedInformer.addEventHandler(new ResourceEventHandler<T>() {
+    this.associatedWith = Objects.requireNonNullElseGet(associatedWith, () -> cr -> {
+      final var metadata = cr.getMetadata();
+      return getStore().getByKey(Cache.namespaceKeyFunc(metadata.getNamespace(),
+          metadata.getName()));
+    });
+
+    sharedInformer.addEventHandler(new ResourceEventHandler<>() {
       @Override
       public void onAdd(T t) {
         propagateEvent(InformerEvent.Action.ADD, t, null);
@@ -64,7 +75,7 @@ public void onDelete(T t, boolean b) {
   }
 
   private void propagateEvent(InformerEvent.Action action, T object, T oldObject) {
-    var uids = mapper.map(object);
+    var uids = resourceToUIDs.apply(object);
     if (uids.isEmpty()) {
       return;
     }
@@ -88,12 +99,19 @@ public Store<T> getStore() {
     return sharedInformer.getStore();
   }
 
-  public SharedInformer<T> getSharedInformer() {
-    return sharedInformer;
+  /**
+   * Retrieves the informed resource associated with the specified primary resource as defined by
+   * the function provided when this InformerEventSource was created
+   * 
+   * @param resource the primary resource we want to retrieve the associated resource for
+   * @return the informed resource associated with the specified primary resource
+   */
+  public T getAssociated(HasMetadata resource) {
+    return associatedWith.apply(resource);
   }
 
-  public interface ResourceToRelatedCustomResourceUIDMapper<T> {
-    List<String> map(T resource);
-  }
 
+  public SharedInformer<T> getSharedInformer() {
+    return sharedInformer;
+  }
 }

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

@@ -0,0 +1,32 @@
+package io.javaoperatorsdk.operator.processing.event.internal;
+
+import java.util.Collections;
+import java.util.Set;
+import java.util.function.Function;
+
+import io.fabric8.kubernetes.api.model.HasMetadata;
+
+public class Mappers {
+  public static <T extends HasMetadata> Function<T, Set<String>> fromAnnotation(
+      String annotationKey) {
+    return fromMetadata(annotationKey, false);
+  }
+
+  public static <T extends HasMetadata> Function<T, Set<String>> fromLabel(
+      String labelKey) {
+    return fromMetadata(labelKey, true);
+  }
+
+  private static <T extends HasMetadata> Function<T, Set<String>> fromMetadata(
+      String key, boolean isLabel) {
+    return resource -> {
+      final var metadata = resource.getMetadata();
+      if (metadata == null) {
+        return Collections.emptySet();
+      } else {
+        final var map = isLabel ? metadata.getLabels() : metadata.getAnnotations();
+        return map != null ? Set.of(map.get(key)) : Collections.emptySet();
+      }
+    };
+  }
+}

operator-framework/src/test/java/io/javaoperatorsdk/operator/sample/informereventsource/InformerEventSourceTestCustomResourceController.java

@@ -1,23 +1,18 @@
 package io.javaoperatorsdk.operator.sample.informereventsource;
 
-import java.util.Arrays;
-import java.util.Collections;
-
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import io.fabric8.kubernetes.api.model.ConfigMap;
 import io.fabric8.kubernetes.client.KubernetesClient;
-import io.fabric8.kubernetes.client.informers.SharedInformer;
-import io.fabric8.kubernetes.client.informers.SharedInformerFactory;
-import io.fabric8.kubernetes.client.informers.cache.Cache;
 import io.javaoperatorsdk.operator.api.Context;
 import io.javaoperatorsdk.operator.api.Controller;
 import io.javaoperatorsdk.operator.api.ResourceController;
 import io.javaoperatorsdk.operator.api.UpdateControl;
 import io.javaoperatorsdk.operator.junit.KubernetesClientAware;
 import io.javaoperatorsdk.operator.processing.event.EventSourceManager;
 import io.javaoperatorsdk.operator.processing.event.internal.InformerEventSource;
+import io.javaoperatorsdk.operator.processing.event.internal.Mappers;
 
 import static io.javaoperatorsdk.operator.api.Controller.NO_FINALIZER;
 
@@ -36,19 +31,13 @@ public class InformerEventSourceTestCustomResourceController implements
   public static final String TARGET_CONFIG_MAP_KEY = "targetStatus";
 
   private KubernetesClient kubernetesClient;
-  private SharedInformer<ConfigMap> informer;
+  private InformerEventSource<ConfigMap> eventSource;
 
   @Override
   public void init(EventSourceManager eventSourceManager) {
-    SharedInformerFactory sharedInformerFactory = kubernetesClient.informers();
-    informer = sharedInformerFactory.sharedIndexInformerFor(ConfigMap.class, 0);
-    eventSourceManager.registerEventSource("configmap", new InformerEventSource<>(informer,
-        resource -> {
-          if (resource.getMetadata() == null || resource.getMetadata().getAnnotations() == null) {
-            return Collections.emptyList();
-          }
-          return Arrays.asList(resource.getMetadata().getAnnotations().get(RELATED_RESOURCE_UID));
-        }));
+    eventSource = new InformerEventSource<>(kubernetesClient, ConfigMap.class,
+        Mappers.fromAnnotation(RELATED_RESOURCE_UID));
+    eventSourceManager.registerEventSource("configmap", eventSource);
   }
 
   @Override
@@ -58,9 +47,7 @@ public UpdateControl<InformerEventSourceTestCustomResource> createOrUpdateResour
 
     // Reading the config map from the informer not from the API
     // name of the config map same as custom resource for sake of simplicity
-    ConfigMap configMap =
-        informer.getStore().getByKey(Cache.namespaceKeyFunc(resource.getMetadata().getNamespace(),
-            resource.getMetadata().getName()));
+    ConfigMap configMap = eventSource.getAssociated(resource);
 
     String targetStatus = configMap.getData().get(TARGET_CONFIG_MAP_KEY);
     LOGGER.debug("Setting target status for CR: {}", targetStatus);