dbmdz · clorenz · Nov 25, 2025 · Nov 25, 2025 · Nov 25, 2025 · Nov 25, 2025
diff --git a/CHANGES.md b/CHANGES.md
@@ -6,6 +6,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Changed
+
+- *Breaking* Migration to Spring Boot 4
+- Updated testcontainer dependencies to RabbitMQ 4
+
 ## [8.0.1](https://github.com/dbmdz/flusswerk/releases/tag/8.0.0) - 2025-10-08
 
 ### Fixed

diff --git a/README.md b/README.md
@@ -15,15 +15,15 @@ Java application).
 <dependency>
   <groupId>dev.mdz</groupId>
   <artifactId>flusswerk</artifactId>
-  <version>8.0.0</version>
+  <version>9.0.0</version>
 </dependency>
 ```
 
 **Gradle:**
 
 ```groovy
 dependencies {
-    compile group: 'dev.mdz', name: 'flusswerk', version: '8.0.0'
+    compile group: 'dev.mdz', name: 'flusswerk', version: '9.0.0'
 }
 ``` 
 

diff --git a/framework/pom.xml b/framework/pom.xml
@@ -4,7 +4,7 @@
   <parent>
     <groupId>dev.mdz</groupId>
     <artifactId>flusswerk-parent</artifactId>
-    <version>8.0.2-SNAPSHOT</version>
+    <version>9.0.0-SNAPSHOT</version>
   </parent>
   <modelVersion>4.0.0</modelVersion>
 

diff --git a/framework/src/main/java/dev/mdz/flusswerk/engine/Engine.java b/framework/src/main/java/dev/mdz/flusswerk/engine/Engine.java
@@ -109,7 +109,7 @@ public void stop() {
           try {
             rabbitClient.cancel(consumer.getConsumerTag());
           } catch (IOException e) {
-            LOGGER.error("Could not cancel consumer", e);
+            LOGGER.error("Could not cancel consumer with tag=" + consumer.getConsumerTag(), e);
           }
         });
 

diff --git a/integration-tests/pom.xml b/integration-tests/pom.xml
@@ -3,7 +3,7 @@
   <parent>
     <groupId>dev.mdz</groupId>
     <artifactId>flusswerk-parent</artifactId>
-    <version>8.0.2-SNAPSHOT</version>
+    <version>9.0.0-SNAPSHOT</version>
   </parent>
   <modelVersion>4.0.0</modelVersion>
 
@@ -62,6 +62,11 @@
       <artifactId>spring-boot-starter</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter-actuator</artifactId>
+      <scope>test</scope>
+    </dependency>
     <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-actuator-autoconfigure</artifactId>
@@ -70,13 +75,13 @@
     <dependency>
       <groupId>org.testcontainers</groupId>
       <artifactId>testcontainers</artifactId>
-      <version>1.21.3</version>
+      <version>2.0.2</version>
       <scope>test</scope>
     </dependency>
     <dependency>
       <groupId>org.testcontainers</groupId>
-      <artifactId>junit-jupiter</artifactId>
-      <version>1.21.3</version>
+      <artifactId>testcontainers-junit-jupiter</artifactId>
+      <version>2.0.1</version>
       <scope>test</scope>
     </dependency>
     <dependency>

diff --git a/...ation-tests/src/test/java/dev/mdz/flusswerk/integration/IntegrationTestConfiguration.java b/...ation-tests/src/test/java/dev/mdz/flusswerk/integration/IntegrationTestConfiguration.java
@@ -0,0 +1,15 @@
+package dev.mdz.flusswerk.integration;
+
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
+import org.springframework.boot.test.context.TestConfiguration;
+import org.springframework.context.annotation.Bean;
+
+@TestConfiguration
+public class IntegrationTestConfiguration {
+
+  @Bean
+  MeterRegistry meterRegistry() {
+    return new SimpleMeterRegistry();
+  }
+}
diff --git a/integration-tests/src/test/java/dev/mdz/flusswerk/integration/NoFlowTest.java b/integration-tests/src/test/java/dev/mdz/flusswerk/integration/NoFlowTest.java
@@ -13,18 +13,18 @@
 import dev.mdz.flusswerk.rabbitmq.RabbitMQ;
 import java.io.IOException;
 import java.util.List;
+import java.util.Optional;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.boot.actuate.autoconfigure.metrics.CompositeMeterRegistryAutoConfiguration;
-import org.springframework.boot.actuate.autoconfigure.metrics.MetricsAutoConfiguration;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.context.TestConfiguration;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Import;
 import org.springframework.context.annotation.Primary;
+import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit.jupiter.SpringExtension;
 import org.testcontainers.containers.RabbitMQContainer;
@@ -39,13 +39,26 @@
       FlusswerkConfiguration.class,
       NoFlowTest.NoFlowTestConfiguration.class
     })
-@Import({MetricsAutoConfiguration.class, CompositeMeterRegistryAutoConfiguration.class})
+@Import(IntegrationTestConfiguration.class)
 @DisplayName("When Flusswerk is created without a Flow")
+@DirtiesContext(classMode = DirtiesContext.ClassMode.AFTER_EACH_TEST_METHOD)
 @Testcontainers
 public class NoFlowTest {
   @Container
   static final RabbitMQContainer rabbitMQContainer =
-      new RabbitMQContainer("rabbitmq:3-management-alpine");
+      new RabbitMQContainer("rabbitmq:4-management-alpine");
+
+  private final Engine engine;
+  private final RabbitMQ rabbitMQ;
+  private final RabbitUtil rabbitUtil;
+
+  @Autowired
+  public NoFlowTest(
+      Optional<Engine> engine, RoutingProperties routingProperties, RabbitMQ rabbitMQ) {
+    this.engine = engine.orElse(null);
+    this.rabbitMQ = rabbitMQ;
+    this.rabbitUtil = new RabbitUtil(rabbitMQ, routingProperties);
+  }
 
   @TestConfiguration
   static class NoFlowTestConfiguration {
@@ -69,17 +82,6 @@ public IncomingMessageType incomingMessageType() {
     }
   }
 
-  private final Engine engine;
-  private final RabbitMQ rabbitMQ;
-  private final RabbitUtil rabbitUtil;
-
-  @Autowired
-  public NoFlowTest(Engine engine, RoutingProperties routingProperties, RabbitMQ rabbitMQ) {
-    this.engine = engine;
-    this.rabbitMQ = rabbitMQ;
-    this.rabbitUtil = new RabbitUtil(rabbitMQ, routingProperties);
-  }
-
   @AfterEach
   void stopEngine() {
     rabbitUtil.purgeQueues();

diff --git a/integration-tests/src/test/java/dev/mdz/flusswerk/integration/processing/ReconnectTest.java b/integration-tests/src/test/java/dev/mdz/flusswerk/integration/processing/ReconnectTest.java
@@ -13,6 +13,7 @@
 import dev.mdz.flusswerk.engine.Engine;
 import dev.mdz.flusswerk.flow.FlowSpec;
 import dev.mdz.flusswerk.flow.builder.FlowBuilder;
+import dev.mdz.flusswerk.integration.IntegrationTestConfiguration;
 import dev.mdz.flusswerk.integration.RabbitUtil;
 import dev.mdz.flusswerk.integration.TestMessage;
 import dev.mdz.flusswerk.jackson.FlusswerkObjectMapper;
@@ -29,16 +30,13 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.TimeoutException;
-import org.junit.Rule;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.boot.actuate.autoconfigure.metrics.CompositeMeterRegistryAutoConfiguration;
-import org.springframework.boot.actuate.autoconfigure.metrics.MetricsAutoConfiguration;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.context.TestConfiguration;
 import org.springframework.context.annotation.Bean;
@@ -62,23 +60,23 @@
       FlusswerkConfiguration.class,
       ReconnectTest.FlowConfiguration.class
     })
-@Import({MetricsAutoConfiguration.class, CompositeMeterRegistryAutoConfiguration.class})
+@Import(IntegrationTestConfiguration.class)
 @DisplayName("When the RabbitMQ connection is lost")
 @DirtiesContext(classMode = ClassMode.AFTER_EACH_TEST_METHOD)
 @Testcontainers
 public class ReconnectTest {
   private static final Logger log = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
 
-  @Rule static final Network network = Network.newNetwork();
+  public static final Network network = Network.newNetwork();
 
   @Container
   static final RabbitMQContainer rabbitMQContainer =
-      new RabbitMQContainer("rabbitmq:3-management-alpine")
+      new RabbitMQContainer("rabbitmq:4-management-alpine")
           .withNetwork(network)
           .withExposedPorts(5672)
           .withNetworkAliases("rabbitmq");
 
-  @Rule
+  @Container
   static final ToxiproxyContainer toxiProxy =
       new ToxiproxyContainer("ghcr.io/shopify/toxiproxy:2.5.0")
           .withExposedPorts(5672, 8474)
@@ -233,7 +231,9 @@ void recoverFromDisruptionDuringStartup() throws IOException, InterruptedExcepti
   @Test
   public void recoveryAfterDisruptionDuringProcessing() throws Exception {
     TestMessage input = new TestMessage("hello world");
-    engine.start();
+    if (!engine.isRunning()) {
+      engine.start();
+    }
 
     log.info("Sending message");
     rabbitUtil.send(input);
@@ -270,7 +270,9 @@ public void recoverFromChannelException()
     log.info("Sending message");
     rabbitUtil.send(new TestMessage("hello world"));
     Thread.sleep(500);
-    engine.start();
+    if (!engine.isRunning()) {
+      engine.start();
+    }
     log.info("Closing RabbitMQ channel");
     Channel channel = rabbitConnection.getChannel();
     channel.close();

diff --git a/integration-tests/src/test/java/dev/mdz/flusswerk/integration/processing/RetryTest.java b/integration-tests/src/test/java/dev/mdz/flusswerk/integration/processing/RetryTest.java
@@ -11,6 +11,7 @@
 import dev.mdz.flusswerk.exceptions.RetryProcessingException;
 import dev.mdz.flusswerk.flow.FlowSpec;
 import dev.mdz.flusswerk.flow.builder.FlowBuilder;
+import dev.mdz.flusswerk.integration.IntegrationTestConfiguration;
 import dev.mdz.flusswerk.integration.RabbitUtil;
 import dev.mdz.flusswerk.integration.TestMessage;
 import dev.mdz.flusswerk.model.IncomingMessageType;
@@ -27,8 +28,6 @@
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.boot.actuate.autoconfigure.metrics.CompositeMeterRegistryAutoConfiguration;
-import org.springframework.boot.actuate.autoconfigure.metrics.MetricsAutoConfiguration;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.context.TestConfiguration;
 import org.springframework.context.annotation.Bean;
@@ -50,15 +49,15 @@
       FlusswerkConfiguration.class,
       RetryTest.FlowConfiguration.class,
     })
-@Import({MetricsAutoConfiguration.class, CompositeMeterRegistryAutoConfiguration.class})
+@Import(IntegrationTestConfiguration.class)
 @DisplayName("When processing for a message fails")
 @DirtiesContext(classMode = ClassMode.AFTER_EACH_TEST_METHOD)
 @Testcontainers
 public class RetryTest {
 
   @Container
   static final RabbitMQContainer rabbitMQContainer =
-      new RabbitMQContainer("rabbitmq:3-management-alpine");
+      new RabbitMQContainer("rabbitmq:4-management-alpine");
 
   private final Engine engine;
 
@@ -109,7 +108,9 @@ public FlowSpec flowSpec() {
 
   @BeforeEach
   void startEngine() {
-    engine.start();
+    if (!engine.isRunning()) {
+      engine.start();
+    }
   }
 
   @AfterEach

diff --git a/...tion-tests/src/test/java/dev/mdz/flusswerk/integration/processing/SkipProcessingTest.java b/...tion-tests/src/test/java/dev/mdz/flusswerk/integration/processing/SkipProcessingTest.java
@@ -11,6 +11,7 @@
 import dev.mdz.flusswerk.exceptions.SkipProcessingException;
 import dev.mdz.flusswerk.flow.FlowSpec;
 import dev.mdz.flusswerk.flow.builder.FlowBuilder;
+import dev.mdz.flusswerk.integration.IntegrationTestConfiguration;
 import dev.mdz.flusswerk.integration.RabbitUtil;
 import dev.mdz.flusswerk.integration.TestMessage;
 import dev.mdz.flusswerk.model.IncomingMessageType;
@@ -24,8 +25,6 @@
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.boot.actuate.autoconfigure.metrics.CompositeMeterRegistryAutoConfiguration;
-import org.springframework.boot.actuate.autoconfigure.metrics.MetricsAutoConfiguration;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.context.TestConfiguration;
 import org.springframework.context.annotation.Bean;
@@ -47,15 +46,15 @@
       FlusswerkConfiguration.class,
       SkipProcessingTest.FlowConfiguration.class,
     })
-@Import({MetricsAutoConfiguration.class, CompositeMeterRegistryAutoConfiguration.class})
+@Import(IntegrationTestConfiguration.class)
 @DisplayName("When Flusswerk skips a message")
 @DirtiesContext(classMode = ClassMode.AFTER_EACH_TEST_METHOD)
 @Testcontainers
 public class SkipProcessingTest {
 
   @Container
   static final RabbitMQContainer rabbitMQContainer =
-      new RabbitMQContainer("rabbitmq:3-management-alpine");
+      new RabbitMQContainer("rabbitmq:4-management-alpine");
 
   private final Engine engine;
 
@@ -114,7 +113,9 @@ public FlowSpec flowSpec() {
 
   @BeforeEach
   void startEngine() {
-    engine.start();
+    if (!engine.isRunning()) {
+      engine.start();
+    }
   }
 
   @AfterEach

diff --git a/...ests/src/test/java/dev/mdz/flusswerk/integration/processing/SuccessfulProcessingTest.java b/...ests/src/test/java/dev/mdz/flusswerk/integration/processing/SuccessfulProcessingTest.java
@@ -9,6 +9,7 @@
 import dev.mdz.flusswerk.engine.Engine;
 import dev.mdz.flusswerk.flow.FlowSpec;
 import dev.mdz.flusswerk.flow.builder.FlowBuilder;
+import dev.mdz.flusswerk.integration.IntegrationTestConfiguration;
 import dev.mdz.flusswerk.integration.RabbitUtil;
 import dev.mdz.flusswerk.integration.TestMessage;
 import dev.mdz.flusswerk.model.IncomingMessageType;
@@ -22,8 +23,6 @@
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.boot.actuate.autoconfigure.metrics.CompositeMeterRegistryAutoConfiguration;
-import org.springframework.boot.actuate.autoconfigure.metrics.MetricsAutoConfiguration;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.context.TestConfiguration;
 import org.springframework.context.annotation.Bean;
@@ -45,14 +44,14 @@
       FlusswerkConfiguration.class,
       SuccessfulProcessingTest.FlowConfiguration.class
     })
-@Import({MetricsAutoConfiguration.class, CompositeMeterRegistryAutoConfiguration.class})
+@Import(IntegrationTestConfiguration.class)
 @DisplayName("When Flusswerk successfully processes a message")
 @DirtiesContext(classMode = ClassMode.AFTER_EACH_TEST_METHOD)
 @Testcontainers
 public class SuccessfulProcessingTest {
   @Container
   static final RabbitMQContainer rabbitMQContainer =
-      new RabbitMQContainer("rabbitmq:3-management-alpine");
+      new RabbitMQContainer("rabbitmq:4-management-alpine");
 
   private final Engine engine;
 
@@ -94,7 +93,9 @@ public FlowSpec flowSpec() {
 
   @BeforeEach
   void startEngine() {
-    engine.start();
+    if (!engine.isRunning()) {
+      engine.start();
+    }
   }
 
   @AfterEach