Add AggregatedMetrics to support multiple Metrics implementations

docs/content/en/docs/documentation/observability.md

@@ -51,7 +51,7 @@ Operator operator = new Operator(client, o -> o.withMetrics(metrics));
 ### Micrometer implementation
 
 The micrometer implementation is typically created using one of the provided factory methods which, depending on which
-is used, will return either a ready to use instance or a builder allowing users to customized how the implementation
+is used, will return either a ready to use instance or a builder allowing users to customize how the implementation
 behaves, in particular when it comes to the granularity of collected metrics. It is, for example, possible to collect
 metrics on a per-resource basis via tags that are associated with meters. This is the default, historical behavior but
 this will change in a future version of JOSDK because this dramatically increases the cardinality of metrics, which
@@ -62,14 +62,13 @@ instance via:
 
 ```java
 MeterRegistry registry; // initialize your registry implementation
-Metrics metrics = new MicrometerMetrics(registry);
+Metrics metrics = MicrometerMetrics.newMicrometerMetricsBuilder(registry).build();
 ```
 
-Note, however, that this constructor is deprecated and we encourage you to use the factory methods instead, which either
-return a fully pre-configured instance or a builder object that will allow you to configure more easily how the instance
-will behave. You can, for example, configure whether or not the implementation should collect metrics on a per-resource
-basis, whether or not associated meters should be removed when a resource is deleted and how the clean-up is performed.
-See the relevant classes documentation for more details.
+The class provides factory methods which either return a fully pre-configured instance or a builder object that will
+allow you to configure more easily how the instance will behave. You can, for example, configure whether the
+implementation should collect metrics on a per-resource basis, whether associated meters should be removed when a
+resource is deleted and how the clean-up is performed. See the relevant classes documentation for more details.
 
 For example, the following will create a `MicrometerMetrics` instance configured to collect metrics on a per-resource
 basis, deleting the associated meters after 5 seconds when a resource is deleted, using up to 2 threads to do so.
@@ -109,4 +108,30 @@ brackets (`[]`) won't be present when per-resource collection is disabled and ta
 omitted if the associated value is empty. Of note, when in the context of controllers' execution metrics, these tag
 names are prefixed with `resource.`. This prefix might be removed in a future version for greater consistency.
 
+### Aggregated Metrics
 
+The `AggregatedMetrics` class provides a way to combine multiple metrics providers into a single metrics instance using
+the composite pattern. This is particularly useful when you want to simultaneously collect metrics data from different
+monitoring systems or providers.
+
+You can create an `AggregatedMetrics` instance by providing a list of existing metrics implementations:
+
+```java
+// create individual metrics instances
+Metrics micrometerMetrics = MicrometerMetrics.withoutPerResourceMetrics(registry);
+Metrics customMetrics = new MyCustomMetrics();
+Metrics loggingMetrics = new LoggingMetrics();
+
+// combine them into a single aggregated instance
+Metrics aggregatedMetrics = new AggregatedMetrics(List.of(
+    micrometerMetrics, 
+    customMetrics, 
+    loggingMetrics
+));
+
+// use the aggregated metrics with your operator
+Operator operator = new Operator(client, o -> o.withMetrics(aggregatedMetrics));
+```
+
+This approach allows you to easily combine different metrics collection strategies, such as sending metrics to both
+Prometheus (via Micrometer) and a custom logging system simultaneously.

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

@@ -0,0 +1,105 @@
+package io.javaoperatorsdk.operator.api.monitoring;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+
+import io.fabric8.kubernetes.api.model.HasMetadata;
+import io.javaoperatorsdk.operator.api.reconciler.RetryInfo;
+import io.javaoperatorsdk.operator.processing.Controller;
+import io.javaoperatorsdk.operator.processing.event.Event;
+import io.javaoperatorsdk.operator.processing.event.ResourceID;
+
+/**
+ * An aggregated implementation of the {@link Metrics} interface that delegates method calls to a
+ * collection of {@link Metrics} instances using the composite pattern.
+ *
+ * <p>This class allows multiple metrics providers to be combined into a single metrics instance,
+ * enabling simultaneous collection of metrics data by different monitoring systems or providers.
+ * All method calls are delegated to each metrics instance in the list in the order they were
+ * provided to the constructor.
+ *
+ * <p><strong>Important:</strong> The {@link #timeControllerExecution(ControllerExecution)} method
+ * is handled specially - it is only invoked on the first metrics instance in the list, since it's
+ * not an idempotent operation and can only be executed once. The controller execution cannot be
+ * repeated multiple times as it would produce side effects and potentially inconsistent results.
+ *
+ * <p>All other methods are called on every metrics instance in the list, preserving the order of
+ * execution as specified in the constructor.
+ *
+ * @see Metrics
+ */
+public final class AggregatedMetrics implements Metrics {
+
+  private final List<Metrics> metricsList;
+
+  /**
+   * Creates a new AggregatedMetrics instance that will delegate method calls to the provided list
+   * of metrics instances.
+   *
+   * @param metricsList the list of metrics instances to delegate to; must not be null and must
+   *     contain at least one metrics instance
+   * @throws NullPointerException if metricsList is null
+   * @throws IllegalArgumentException if metricsList is empty
+   */
+  public AggregatedMetrics(List<Metrics> metricsList) {
+    Objects.requireNonNull(metricsList, "metricsList must not be null");
+    if (metricsList.isEmpty()) {
+      throw new IllegalArgumentException("metricsList must contain at least one Metrics instance");
+    }
+    this.metricsList = List.copyOf(metricsList);
+  }
+
+  @Override
+  public void controllerRegistered(Controller<? extends HasMetadata> controller) {
+    metricsList.forEach(metrics -> metrics.controllerRegistered(controller));
+  }
+
+  @Override
+  public void receivedEvent(Event event, Map<String, Object> metadata) {
+    metricsList.forEach(metrics -> metrics.receivedEvent(event, metadata));
+  }
+
+  @Override
+  public void reconcileCustomResource(
+      HasMetadata resource, RetryInfo retryInfo, Map<String, Object> metadata) {
+    metricsList.forEach(metrics -> metrics.reconcileCustomResource(resource, retryInfo, metadata));
+  }
+
+  @Override
+  public void failedReconciliation(
+      HasMetadata resource, Exception exception, Map<String, Object> metadata) {
+    metricsList.forEach(metrics -> metrics.failedReconciliation(resource, exception, metadata));
+  }
+
+  @Override
+  public void reconciliationExecutionStarted(HasMetadata resource, Map<String, Object> metadata) {
+    metricsList.forEach(metrics -> metrics.reconciliationExecutionStarted(resource, metadata));
+  }
+
+  @Override
+  public void reconciliationExecutionFinished(HasMetadata resource, Map<String, Object> metadata) {
+    metricsList.forEach(metrics -> metrics.reconciliationExecutionFinished(resource, metadata));
+  }
+
+  @Override
+  public void cleanupDoneFor(ResourceID resourceID, Map<String, Object> metadata) {
+    metricsList.forEach(metrics -> metrics.cleanupDoneFor(resourceID, metadata));
+  }
+
+  @Override
+  public void finishedReconciliation(HasMetadata resource, Map<String, Object> metadata) {
+    metricsList.forEach(metrics -> metrics.finishedReconciliation(resource, metadata));
+  }
+
+  @Override
+  public <T> T timeControllerExecution(ControllerExecution<T> execution) throws Exception {
+    return metricsList.get(0).timeControllerExecution(execution);
+  }
+
+  @Override
+  public <T extends Map<?, ?>> T monitorSizeOf(T map, String name) {
+    metricsList.forEach(metrics -> metrics.monitorSizeOf(map, name));
+    return map;
+  }
+}

operator-framework-core/src/test/java/io/javaoperatorsdk/operator/api/monitoring/AggregatedMetricsTest.java

@@ -0,0 +1,180 @@
+package io.javaoperatorsdk.operator.api.monitoring;
+
+import java.util.List;
+import java.util.Map;
+
+import org.junit.jupiter.api.Test;
+
+import io.fabric8.kubernetes.api.model.HasMetadata;
+import io.javaoperatorsdk.operator.api.reconciler.RetryInfo;
+import io.javaoperatorsdk.operator.processing.Controller;
+import io.javaoperatorsdk.operator.processing.event.Event;
+import io.javaoperatorsdk.operator.processing.event.ResourceID;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.*;
+
+class AggregatedMetricsTest {
+
+  private final Metrics metrics1 = mock();
+  private final Metrics metrics2 = mock();
+  private final Metrics metrics3 = mock();
+  private final Controller<HasMetadata> controller = mock();
+  private final Event event = mock();
+  private final HasMetadata resource = mock();
+  private final RetryInfo retryInfo = mock();
+  private final ResourceID resourceID = mock();
+  private final Metrics.ControllerExecution<String> controllerExecution = mock();
+
+  private final Map<String, Object> metadata = Map.of("kind", "TestResource");
+  private final AggregatedMetrics aggregatedMetrics =
+      new AggregatedMetrics(List.of(metrics1, metrics2, metrics3));
+
+  @Test
+  void constructor_shouldThrowNullPointerExceptionWhenMetricsListIsNull() {
+    assertThatThrownBy(() -> new AggregatedMetrics(null))
+        .isInstanceOf(NullPointerException.class)
+        .hasMessage("metricsList must not be null");
+  }
+
+  @Test
+  void constructor_shouldThrowIllegalArgumentExceptionWhenMetricsListIsEmpty() {
+    assertThatThrownBy(() -> new AggregatedMetrics(List.of()))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("metricsList must contain at least one Metrics instance");
+  }
+
+  @Test
+  void controllerRegistered_shouldDelegateToAllMetricsInOrder() {
+    aggregatedMetrics.controllerRegistered(controller);
+
+    final var inOrder = inOrder(metrics1, metrics2, metrics3);
+    inOrder.verify(metrics1).controllerRegistered(controller);
+    inOrder.verify(metrics2).controllerRegistered(controller);
+    inOrder.verify(metrics3).controllerRegistered(controller);
+    verifyNoMoreInteractions(metrics1, metrics2, metrics3);
+  }
+
+  @Test
+  void receivedEvent_shouldDelegateToAllMetricsInOrder() {
+    aggregatedMetrics.receivedEvent(event, metadata);
+
+    final var inOrder = inOrder(metrics1, metrics2, metrics3);
+    inOrder.verify(metrics1).receivedEvent(event, metadata);
+    inOrder.verify(metrics2).receivedEvent(event, metadata);
+    inOrder.verify(metrics3).receivedEvent(event, metadata);
+    verifyNoMoreInteractions(metrics1, metrics2, metrics3);
+  }
+
+  @Test
+  void reconcileCustomResource_shouldDelegateToAllMetricsInOrder() {
+    aggregatedMetrics.reconcileCustomResource(resource, retryInfo, metadata);
+
+    final var inOrder = inOrder(metrics1, metrics2, metrics3);
+    inOrder.verify(metrics1).reconcileCustomResource(resource, retryInfo, metadata);
+    inOrder.verify(metrics2).reconcileCustomResource(resource, retryInfo, metadata);
+    inOrder.verify(metrics3).reconcileCustomResource(resource, retryInfo, metadata);
+    verifyNoMoreInteractions(metrics1, metrics2, metrics3);
+  }
+
+  @Test
+  void failedReconciliation_shouldDelegateToAllMetricsInOrder() {
+    final var exception = new RuntimeException("Test exception");
+
+    aggregatedMetrics.failedReconciliation(resource, exception, metadata);
+
+    final var inOrder = inOrder(metrics1, metrics2, metrics3);
+    inOrder.verify(metrics1).failedReconciliation(resource, exception, metadata);
+    inOrder.verify(metrics2).failedReconciliation(resource, exception, metadata);
+    inOrder.verify(metrics3).failedReconciliation(resource, exception, metadata);
+    verifyNoMoreInteractions(metrics1, metrics2, metrics3);
+  }
+
+  @Test
+  void reconciliationExecutionStarted_shouldDelegateToAllMetricsInOrder() {
+    aggregatedMetrics.reconciliationExecutionStarted(resource, metadata);
+
+    final var inOrder = inOrder(metrics1, metrics2, metrics3);
+    inOrder.verify(metrics1).reconciliationExecutionStarted(resource, metadata);
+    inOrder.verify(metrics2).reconciliationExecutionStarted(resource, metadata);
+    inOrder.verify(metrics3).reconciliationExecutionStarted(resource, metadata);
+    verifyNoMoreInteractions(metrics1, metrics2, metrics3);
+  }
+
+  @Test
+  void reconciliationExecutionFinished_shouldDelegateToAllMetricsInOrder() {
+    aggregatedMetrics.reconciliationExecutionFinished(resource, metadata);
+
+    final var inOrder = inOrder(metrics1, metrics2, metrics3);
+    inOrder.verify(metrics1).reconciliationExecutionFinished(resource, metadata);
+    inOrder.verify(metrics2).reconciliationExecutionFinished(resource, metadata);
+    inOrder.verify(metrics3).reconciliationExecutionFinished(resource, metadata);
+    verifyNoMoreInteractions(metrics1, metrics2, metrics3);
+  }
+
+  @Test
+  void cleanupDoneFor_shouldDelegateToAllMetricsInOrder() {
+    aggregatedMetrics.cleanupDoneFor(resourceID, metadata);
+
+    final var inOrder = inOrder(metrics1, metrics2, metrics3);
+    inOrder.verify(metrics1).cleanupDoneFor(resourceID, metadata);
+    inOrder.verify(metrics2).cleanupDoneFor(resourceID, metadata);
+    inOrder.verify(metrics3).cleanupDoneFor(resourceID, metadata);
+    verifyNoMoreInteractions(metrics1, metrics2, metrics3);
+  }
+
+  @Test
+  void finishedReconciliation_shouldDelegateToAllMetricsInOrder() {
+    aggregatedMetrics.finishedReconciliation(resource, metadata);
+
+    final var inOrder = inOrder(metrics1, metrics2, metrics3);
+    inOrder.verify(metrics1).finishedReconciliation(resource, metadata);
+    inOrder.verify(metrics2).finishedReconciliation(resource, metadata);
+    inOrder.verify(metrics3).finishedReconciliation(resource, metadata);
+    verifyNoMoreInteractions(metrics1, metrics2, metrics3);
+  }
+
+  @Test
+  void timeControllerExecution_shouldOnlyDelegateToFirstMetrics() throws Exception {
+    final var expectedResult = "execution result";
+    when(metrics1.timeControllerExecution(controllerExecution)).thenReturn(expectedResult);
+
+    final var result = aggregatedMetrics.timeControllerExecution(controllerExecution);
+
+    assertThat(result).isEqualTo(expectedResult);
+    verify(metrics1).timeControllerExecution(controllerExecution);
+    verify(metrics2, never()).timeControllerExecution(any());
+    verify(metrics3, never()).timeControllerExecution(any());
+    verifyNoMoreInteractions(metrics1, metrics2, metrics3);
+  }
+
+  @Test
+  void timeControllerExecution_shouldPropagateException() throws Exception {
+    final var expectedException = new RuntimeException("Controller execution failed");
+    when(metrics1.timeControllerExecution(controllerExecution)).thenThrow(expectedException);
+
+    assertThatThrownBy(() -> aggregatedMetrics.timeControllerExecution(controllerExecution))
+        .isSameAs(expectedException);
+
+    verify(metrics1).timeControllerExecution(controllerExecution);
+    verify(metrics2, never()).timeControllerExecution(any());
+    verify(metrics3, never()).timeControllerExecution(any());
+    verifyNoMoreInteractions(metrics1, metrics2, metrics3);
+  }
+
+  @Test
+  void monitorSizeOf_shouldDelegateToAllMetricsInOrderAndReturnOriginalMap() {
+    final var testMap = Map.of("key1", "value1");
+    final var mapName = "testMap";
+
+    final var result = aggregatedMetrics.monitorSizeOf(testMap, mapName);
+
+    assertThat(result).isSameAs(testMap);
+    verify(metrics1).monitorSizeOf(testMap, mapName);
+    verify(metrics2).monitorSizeOf(testMap, mapName);
+    verify(metrics3).monitorSizeOf(testMap, mapName);
+    verifyNoMoreInteractions(metrics1, metrics2, metrics3);
+  }
+}