GH-342 - Allow disabling event externalization.

We now expose spring.modulith.events.externalization.enabled that can be set to false to disable the event externalization completely. Useful in test cases, for example.

spring-modulith-events/spring-modulith-events-amqp/src/main/java/org/springframework/modulith/events/amqp/RabbitEventExternalizerConfiguration.java

@@ -23,6 +23,7 @@ import org.springframework.beans.factory.BeanFactory;
 import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.expression.BeanFactoryResolver;
 import org.springframework.expression.spel.support.StandardEvaluationContext;
@@ -40,6 +41,9 @@ import org.springframework.modulith.events.support.DelegatingEventExternalizer;
 @AutoConfiguration
 @AutoConfigureAfter(EventExternalizationAutoConfiguration.class)
 @ConditionalOnClass(RabbitTemplate.class)
+@ConditionalOnProperty(name = "spring.modulith.events.externalization.enabled",
+		havingValue = "true",
+		matchIfMissing = true)
 class RabbitEventExternalizerConfiguration {
 
 	private static final Logger logger = LoggerFactory.getLogger(RabbitEventExternalizerConfiguration.class);

spring-modulith-events/spring-modulith-events-amqp/src/test/java/org/springframework/modulith/events/amqp/RabbitEventExternalizerConfigurationIntegrationTests.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.modulith.events.amqp;
+
+import static org.assertj.core.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.amqp.rabbit.core.RabbitMessageOperations;
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.modulith.events.EventExternalizationConfiguration;
+import org.springframework.modulith.events.support.DelegatingEventExternalizer;
+
+/**
+ * Integration tests for {@link RabbitEventExternalizerConfiguration}.
+ *
+ * @author Oliver Drotbohm
+ * @since 1.1
+ */
+class RabbitEventExternalizerConfigurationIntegrationTests {
+
+	@Test // GH-342
+	void registersExternalizerByDefault() {
+
+		basicSetup()
+				.run(ctxt -> {
+					assertThat(ctxt).hasSingleBean(DelegatingEventExternalizer.class);
+				});
+	}
+
+	@Test // GH-342
+	void disablesExternalizationIfConfigured() {
+
+		basicSetup()
+				.withPropertyValues("spring.modulith.events.externalization.enabled=false")
+				.run(ctxt -> {
+					assertThat(ctxt).doesNotHaveBean(DelegatingEventExternalizer.class);
+				});
+	}
+
+	private ApplicationContextRunner basicSetup() {
+
+		return new ApplicationContextRunner()
+				.withConfiguration(
+						AutoConfigurations.of(RabbitEventExternalizerConfiguration.class))
+				.withBean(EventExternalizationConfiguration.class, () -> EventExternalizationConfiguration.disabled())
+				.withBean(RabbitMessageOperations.class, () -> mock(RabbitMessageOperations.class));
+	}
+}

spring-modulith-events/spring-modulith-events-api/src/main/java/org/springframework/modulith/events/EventExternalizationConfiguration.java

@@ -77,6 +77,15 @@ public interface EventExternalizationConfiguration {
 		return new Selector();
 	}
 
+	/**
+	 * Disables event externalization by not matching any events at all.
+	 *
+	 * @return will never be {@literal null}.
+	 */
+	public static EventExternalizationConfiguration disabled() {
+		return externalizing().select(__ -> false).build();
+	}
+
 	/**
 	 * A {@link Predicate} to select all events annotated as to be externalized. The currently supported annotations are:
 	 * <ul>

spring-modulith-events/spring-modulith-events-core/src/main/java/org/springframework/modulith/events/config/EventExternalizationAutoConfiguration.java

@@ -23,6 +23,7 @@ import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.autoconfigure.AutoConfigurationPackages;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.context.ApplicationListener;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Role;
@@ -30,7 +31,6 @@ import org.springframework.context.event.EventListenerFactory;
 import org.springframework.core.Ordered;
 import org.springframework.modulith.events.EventExternalizationConfiguration;
 import org.springframework.modulith.events.core.ConditionalEventListener;
-import org.springframework.modulith.events.support.PersistentApplicationEventMulticaster;
 import org.springframework.transaction.event.TransactionalApplicationListenerMethodAdapter;
 import org.springframework.transaction.event.TransactionalEventListenerFactory;
 
@@ -40,6 +40,9 @@ import org.springframework.transaction.event.TransactionalEventListenerFactory;
  * @author Oliver Drotbohm
  * @since 1.1
  */
+@ConditionalOnProperty(name = "spring.modulith.events.externalization.enabled",
+		havingValue = "true",
+		matchIfMissing = true)
 @AutoConfiguration
 @AutoConfigureAfter(EventPublicationConfiguration.class)
 public class EventExternalizationAutoConfiguration {

spring-modulith-events/spring-modulith-events-core/src/main/resources/META-INF/spring-configuration-metadata.json

@@ -11,6 +11,12 @@
 			"type": "java.lang.boolean",
 			"description": "Whether to republish outstanding event publications on restarts of the application.",
 			"defaultValue": "false"
+		},
+		{
+			"name": "spring.modulith.events.externalization.enabled",
+			"type": "java.lang.boolean",
+			"description": "Whether to enable event externalization.",
+			"defaultValue": "true"
 		}
 	]
 }

spring-modulith-events/spring-modulith-events-jms/src/main/java/org/springframework/modulith/events/jms/JmsEventExternalizerConfiguration.java

@@ -20,6 +20,7 @@ import org.slf4j.LoggerFactory;
 import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.context.annotation.Bean;
 import org.springframework.jms.core.JmsOperations;
 import org.springframework.modulith.events.EventExternalizationConfiguration;
@@ -36,6 +37,9 @@ import org.springframework.modulith.events.support.DelegatingEventExternalizer;
 @AutoConfiguration
 @AutoConfigureAfter(EventExternalizationAutoConfiguration.class)
 @ConditionalOnClass(JmsOperations.class)
+@ConditionalOnProperty(name = "spring.modulith.events.externalization.enabled",
+		havingValue = "true",
+		matchIfMissing = true)
 class JmsEventExternalizerConfiguration {
 
 	private static final Logger logger = LoggerFactory.getLogger(JmsEventExternalizerConfiguration.class);

spring-modulith-events/spring-modulith-events-jms/src/test/java/org/springframework/modulith/events/jms/JmsEventExternalizerConfigurationIntegrationTests.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.modulith.events.jms;
+
+import static org.assertj.core.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.jms.core.JmsOperations;
+import org.springframework.modulith.events.EventExternalizationConfiguration;
+import org.springframework.modulith.events.core.EventSerializer;
+import org.springframework.modulith.events.support.DelegatingEventExternalizer;
+
+/**
+ * Integration tests for {@link JmsEventExternalizerConfiguration}.
+ *
+ * @author Oliver Drotbohm
+ * @since 1.1
+ */
+class JmsEventExternalizerConfigurationIntegrationTests {
+
+	@Test // GH-342
+	void registersExternalizerByDefault() {
+
+		basicSetup()
+				.run(ctxt -> {
+					assertThat(ctxt).hasSingleBean(DelegatingEventExternalizer.class);
+				});
+	}
+
+	@Test // GH-342
+	void disablesExternalizationIfConfigured() {
+
+		basicSetup()
+				.withPropertyValues("spring.modulith.events.externalization.enabled=false")
+				.run(ctxt -> {
+					assertThat(ctxt).doesNotHaveBean(DelegatingEventExternalizer.class);
+				});
+	}
+
+	private ApplicationContextRunner basicSetup() {
+
+		return new ApplicationContextRunner()
+				.withConfiguration(
+						AutoConfigurations.of(JmsEventExternalizerConfiguration.class))
+				.withBean(EventExternalizationConfiguration.class, () -> EventExternalizationConfiguration.disabled())
+				.withBean(EventSerializer.class, () -> mock(EventSerializer.class))
+				.withBean(JmsOperations.class, () -> mock(JmsOperations.class));
+	}
+}

spring-modulith-events/spring-modulith-events-kafka/pom.xml

@@ -40,6 +40,14 @@
 			<optional>true</optional>
 		</dependency>
 
+		<!-- Testing -->
+
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-test</artifactId>
+			<scope>test</scope>
+		</dependency>
+
 	</dependencies>
 
 </project>

spring-modulith-events/spring-modulith-events-kafka/src/main/java/org/springframework/modulith/events/kafka/KafkaEventExternalizerConfiguration.java

@@ -21,6 +21,7 @@ import org.springframework.beans.factory.BeanFactory;
 import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.expression.BeanFactoryResolver;
 import org.springframework.expression.spel.support.StandardEvaluationContext;
@@ -37,9 +38,13 @@ import org.springframework.modulith.events.support.DelegatingEventExternalizer;
  * @author Oliver Drotbohm
  * @since 1.1
  */
+
 @AutoConfiguration
 @AutoConfigureAfter(EventExternalizationAutoConfiguration.class)
 @ConditionalOnClass(KafkaTemplate.class)
+@ConditionalOnProperty(name = "spring.modulith.events.externalization.enabled",
+		havingValue = "true",
+		matchIfMissing = true)
 class KafkaEventExternalizerConfiguration {
 
 	private static final Logger logger = LoggerFactory.getLogger(KafkaEventExternalizerConfiguration.class);

spring-modulith-events/spring-modulith-events-kafka/src/test/java/org/springframework/modulith/events/kafka/KafkaEventExternalizerConfigurationIntegrationTests.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.modulith.events.kafka;
+
+import static org.assertj.core.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.kafka.core.KafkaOperations;
+import org.springframework.modulith.events.EventExternalizationConfiguration;
+import org.springframework.modulith.events.support.DelegatingEventExternalizer;
+
+/**
+ * Integration tests for {@link KafkaEventExternalizerConfiguration}.
+ *
+ * @author Oliver Drotbohm
+ * @since 1.1
+ */
+class KafkaEventExternalizerConfigurationIntegrationTests {
+
+	@Test // GH-342
+	void registersExternalizerByDefault() {
+
+		basicSetup()
+				.run(ctxt -> {
+					assertThat(ctxt).hasSingleBean(DelegatingEventExternalizer.class);
+				});
+	}
+
+	@Test // GH-342
+	void disablesExternalizationIfConfigured() {
+
+		basicSetup()
+				.withPropertyValues("spring.modulith.events.externalization.enabled=false")
+				.run(ctxt -> {
+					assertThat(ctxt).doesNotHaveBean(DelegatingEventExternalizer.class);
+				});
+	}
+
+	private ApplicationContextRunner basicSetup() {
+
+		return new ApplicationContextRunner()
+				.withConfiguration(
+						AutoConfigurations.of(KafkaEventExternalizerConfiguration.class))
+				.withBean(EventExternalizationConfiguration.class, () -> EventExternalizationConfiguration.disabled())
+				.withBean(KafkaOperations.class, () -> mock(KafkaOperations.class));
+	}
+}

src/docs/antora/modules/ROOT/pages/appendix.adoc

@@ -13,6 +13,10 @@
 |`true`
 |Whether to configure defaults for the async processing termination, namely to wait for task completion for 2 seconds. See `TaskExecutionProperties` for details.
 
+|`spring.modulith.events.externalization.enabled`
+|`true`
+|Whether to enable event externalization.
+
 |`spring.modulith.events.jdbc.schema-initialization.enabled`
 |`false`
 |Whether to initialize the JDBC event publication schema.