only load implementation specific auto config if @ConditionalOnBusEnabled

fixes gh-12

spring-cloud-bus/src/main/java/org/springframework/cloud/bus/BusAutoConfiguration.java

@@ -36,9 +36,11 @@ import org.springframework.messaging.SubscribableChannel;
  * @author Dave Syer
  */
 @Configuration
-@ConditionalOnProperty(value = "spring.cloud.bus.enabled", matchIfMissing = true)
+@ConditionalOnBusEnabled
 public class BusAutoConfiguration {
 
+	public static final String SPRING_CLOUD_BUS_ENABLED = "spring.cloud.bus.enabled";
+
 	@Autowired
 	private ConfigurableApplicationContext context;
 

spring-cloud-bus/src/main/java/org/springframework/cloud/bus/ConditionalOnBusEnabled.java

@@ -0,0 +1,17 @@
+package org.springframework.cloud.bus;
+
+import org.springframework.context.annotation.Conditional;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * @author Spencer Gibb
+ */
+@Conditional(OnBusEnabled.class)
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ ElementType.TYPE, ElementType.METHOD })
+public @interface ConditionalOnBusEnabled {
+}

spring-cloud-bus/src/main/java/org/springframework/cloud/bus/OnBusEnabled.java

@@ -0,0 +1,26 @@
+package org.springframework.cloud.bus;
+
+import org.springframework.boot.autoconfigure.condition.ConditionOutcome;
+import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
+import org.springframework.boot.bind.RelaxedPropertyResolver;
+import org.springframework.context.annotation.ConditionContext;
+import org.springframework.core.type.AnnotatedTypeMetadata;
+
+import static org.springframework.cloud.bus.BusAutoConfiguration.SPRING_CLOUD_BUS_ENABLED;
+
+/**
+ * Match if spring.cloud.bus.enabled is missing or not false
+ * @author Spencer Gibb
+ */
+class OnBusEnabled extends SpringBootCondition {
+	@Override
+	public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
+		RelaxedPropertyResolver resolver = new RelaxedPropertyResolver(context.getEnvironment());
+		String enabled = resolver.getProperty(SPRING_CLOUD_BUS_ENABLED);
+
+		if (!"false".equalsIgnoreCase(enabled)) {
+			return ConditionOutcome.match();
+		}
+		return ConditionOutcome.noMatch(SPRING_CLOUD_BUS_ENABLED + " is " + enabled);
+	}
+}

spring-cloud-bus/src/main/java/org/springframework/cloud/bus/amqp/AmqpBusAutoConfiguration.java

@@ -10,6 +10,7 @@ import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.cloud.bus.ConditionalOnBusEnabled;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.integration.dsl.IntegrationFlow;
@@ -23,6 +24,7 @@ import com.fasterxml.jackson.databind.ObjectMapper;
  * @author Spencer Gibb
  */
 @Configuration
+@ConditionalOnBusEnabled
 @ConditionalOnClass(AmqpTemplate.class)
 @ConditionalOnProperty(value = "spring.cloud.bus.amqp.enabled", matchIfMissing = true)
 public class AmqpBusAutoConfiguration {

spring-cloud-bus/src/main/java/org/springframework/cloud/bus/jackson/BusJacksonAutoConfiguration.java

@@ -3,6 +3,7 @@ package org.springframework.cloud.bus.jackson;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.cloud.bus.BusAutoConfiguration;
+import org.springframework.cloud.bus.ConditionalOnBusEnabled;
 import org.springframework.cloud.bus.endpoint.RefreshBusEndpoint;
 import org.springframework.cloud.bus.event.EnvironmentChangeRemoteApplicationEvent;
 import org.springframework.cloud.bus.event.RefreshRemoteApplicationEvent;
@@ -15,6 +16,7 @@ import com.fasterxml.jackson.databind.ObjectMapper;
  * @author Spencer Gibb
  */
 @Configuration
+@ConditionalOnBusEnabled
 @ConditionalOnClass({ RefreshBusEndpoint.class, ObjectMapper.class })
 @AutoConfigureAfter(BusAutoConfiguration.class)
 public class BusJacksonAutoConfiguration {

spring-cloud-bus/src/test/java/org/springframework/cloud/bus/ConditionalOnBusEnabledTests.java

@@ -0,0 +1,71 @@
+package org.springframework.cloud.bus;
+
+import org.junit.After;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.springframework.boot.test.EnvironmentTestUtils;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.springframework.cloud.bus.BusAutoConfiguration.SPRING_CLOUD_BUS_ENABLED;
+
+/**
+ * @author Spencer Gibb
+ */
+public class ConditionalOnBusEnabledTests {
+
+	@Rule
+	public ExpectedException thrown = ExpectedException.none();
+
+	private AnnotationConfigApplicationContext context;
+
+	@After
+	public void tearDown() {
+		if (this.context != null) {
+			this.context.close();
+		}
+	}
+
+	@Test
+	public void busEnabledTrue() {
+		load(MyBusEnabledConfig.class, SPRING_CLOUD_BUS_ENABLED+":true");
+		assertTrue("missing bean from @ConditionalOnBusEnabled config",
+				this.context.containsBean("foo"));
+	}
+
+	@Test
+	public void busEnabledMissing() {
+		load(MyBusEnabledConfig.class);
+		assertTrue("missing bean from @ConditionalOnBusEnabled config",
+				this.context.containsBean("foo"));
+	}
+
+	@Test
+	public void busDisabled() {
+		load(MyBusEnabledConfig.class, SPRING_CLOUD_BUS_ENABLED+":false");
+		assertFalse("bean exists from disabled @ConditionalOnBusEnabled config",
+				this.context.containsBean("foo"));
+	}
+
+	@Configuration
+	@ConditionalOnBusEnabled
+	protected static class MyBusEnabledConfig {
+
+		@Bean
+		public String foo() {
+			return "foo";
+		}
+
+	}
+
+	private void load(Class<?> config, String... environment) {
+		this.context = new AnnotationConfigApplicationContext();
+		EnvironmentTestUtils.addEnvironment(this.context, environment);
+		this.context.register(config);
+		this.context.refresh();
+	}
+}

spring-cloud-bus/src/test/java/org/springframework/cloud/bus/amqp/AmqpBusAutoConfigurationTests.java

@@ -3,9 +3,14 @@ package org.springframework.cloud.bus.amqp;
 import org.junit.Test;
 import org.springframework.boot.autoconfigure.PropertyPlaceholderAutoConfiguration;
 import org.springframework.boot.autoconfigure.amqp.RabbitAutoConfiguration;
+import org.springframework.boot.test.EnvironmentTestUtils;
 import org.springframework.cloud.bus.BusAutoConfiguration;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.springframework.cloud.bus.BusAutoConfiguration.SPRING_CLOUD_BUS_ENABLED;
+
 /**
  * @author Dave Syer
  */
@@ -14,8 +19,25 @@ public class AmqpBusAutoConfigurationTests {
 	@Test
 	public void contextStarts() throws Exception {
 		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(
-				AmqpBusAutoConfiguration.class, RabbitAutoConfiguration.class,
-				PropertyPlaceholderAutoConfiguration.class, BusAutoConfiguration.class);
+				getConfigClasses());
+		assertTrue(context.containsBean("cloudBusExchange"));
 		context.close();
 	}
+
+	@Test
+	public void notStartedIfBusDisabled() {
+		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+		EnvironmentTestUtils.addEnvironment(context, SPRING_CLOUD_BUS_ENABLED+":false");
+		context.register(getConfigClasses());
+		context.refresh();
+
+		assertFalse(context.containsBean("cloudBusExchange"));
+
+		context.close();
+	}
+
+	private Class[] getConfigClasses() {
+		return new Class[]{AmqpBusAutoConfiguration.class, RabbitAutoConfiguration.class,
+				PropertyPlaceholderAutoConfiguration.class, BusAutoConfiguration.class};
+	}
 }