Fixes issue gh-153 - multiple bootstrap contexts with hierarchy

spring-cloud-context/src/main/java/org/springframework/cloud/bootstrap/BootstrapApplicationListener.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2014 the original author or authors.
+ * Copyright 2013-2017 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.
@@ -57,6 +57,7 @@
  * "application.properties".
  *
  * @author Dave Syer
+ * @author Biju Kunjummen
  *
  */
 public class BootstrapApplicationListener
@@ -77,6 +78,7 @@ public void onApplicationEvent(ApplicationEnvironmentPreparedEvent event) {
 				true)) {
 			return;
 		}
+
 		// don't listen to events in a bootstrap context
 		if (environment.getPropertySources().contains(BOOTSTRAP_PROPERTY_SOURCE_NAME)) {
 			return;
@@ -133,6 +135,7 @@ private ConfigurableApplicationContext bootstrapServiceContext(
 			}
 			sources.add(cls);
 		}
+		sources.add(BootstrapMarkerConfiguration.class);
 		AnnotationAwareOrderComparator.sort(sources);
 		builder.sources(sources.toArray(new Class[sources.size()]));
 		final ConfigurableApplicationContext context = builder.run();
@@ -289,11 +292,26 @@ public void initialize(ConfigurableApplicationContext context) {
 			while (context.getParent() != null && context.getParent() != context) {
 				context = (ConfigurableApplicationContext) context.getParent();
 			}
+			if (isBootstrapContext(context)) {
+				return;
+			}
 			reorderSources(context.getEnvironment());
 			new ParentContextApplicationContextInitializer(this.parent)
 					.initialize(context);
 		}
 
+		/**
+		 * Determines if a context is a Bootstrap context - by the presence of a Marker bean with a specific name
+		 * @param context
+		 * @return if the context is really a bootstrap context
+		 */
+		private boolean isBootstrapContext(ConfigurableApplicationContext context) {
+			if (context.containsBeanDefinition(BootstrapMarkerConfiguration.MARKER_BEAN_NAME)) {
+				return true;
+			}
+			return false;
+		}
+
 		private void reorderSources(ConfigurableEnvironment environment) {
 			PropertySource<?> removed = environment.getPropertySources()
 					.remove(DEFAULT_PROPERTIES);

spring-cloud-context/src/main/java/org/springframework/cloud/bootstrap/BootstrapMarkerConfiguration.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2013-2017 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
+ *
+ *      http://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.cloud.bootstrap;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * This purpose of this @Configuration is to register a Marker configuration just to determine if the Bootstrap
+ * related configuration is already loaded up and if so not to load it up once more.
+ *
+ * @author Biju Kunjummen
+ */
+@Configuration
+class BootstrapMarkerConfiguration {
+
+    static final String MARKER_BEAN_NAME = "bootstrap:bootstrapMarker";
+
+    class BootstrapMarker {}
+
+    @Bean(MARKER_BEAN_NAME)
+    public BootstrapMarker bootstrapMarker() {
+        return new BootstrapMarker();
+    }
+}

spring-cloud-context/src/test/java/org/springframework/cloud/bootstrap/BootstrapListenerHierarchyIntegrationTests.java

@@ -0,0 +1,109 @@
+/*
+ * Copyright 2013-2017 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
+ *
+ *      http://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.cloud.bootstrap;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.After;
+import org.junit.Test;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * Integration tests for Bootstrap Listener's functionality of adding a bootstrap context
+ * as the root Application Context
+ * 
+ * @author Biju Kunjummen
+ */
+public class BootstrapListenerHierarchyIntegrationTests {
+
+	@Test
+	public void shouldAddInABootstrapContext() {
+		ConfigurableApplicationContext context = new SpringApplicationBuilder()
+				.sources(BasicConfiguration.class).web(false).run();
+
+		assertThat(context.getParent()).isNotNull();
+	}
+
+	@Test
+	public void shouldAddInOneBootstrapForABasicParentChildHierarchy() {
+		ConfigurableApplicationContext context = new SpringApplicationBuilder()
+				.sources(RootConfiguration.class).web(false)
+				.child(BasicConfiguration.class).web(false).run();
+
+		// Should be RootConfiguration based context
+		ConfigurableApplicationContext parent = (ConfigurableApplicationContext) context
+				.getParent();
+		assertThat(parent.getBean("rootBean", String.class)).isEqualTo("rootBean");
+
+		// Parent should have the bootstrap context as parent
+		assertThat(parent.getParent()).isNotNull();
+
+		ConfigurableApplicationContext bootstrapContext = (ConfigurableApplicationContext) parent
+				.getParent();
+
+		// The Bootstrap Marker bean should be present
+		assertThat(bootstrapContext
+				.containsLocalBean(BootstrapMarkerConfiguration.MARKER_BEAN_NAME))
+						.isTrue();
+
+		// Bootstrap should be the root, there should be no other parent
+		assertThat(bootstrapContext.getParent()).isNull();
+	}
+
+	@Test
+	public void shouldAddInOneBootstrapForSiblingsBasedHierarchy() {
+		ConfigurableApplicationContext context = new SpringApplicationBuilder()
+				.sources(RootConfiguration.class).web(false)
+				.child(BasicConfiguration.class).web(false)
+				.sibling(BasicConfiguration.class).web(false).run();
+
+		// Should be RootConfiguration based context
+		ConfigurableApplicationContext parent = (ConfigurableApplicationContext) context
+				.getParent();
+		assertThat(parent.getBean("rootBean", String.class)).isEqualTo("rootBean");
+
+		// Parent should have the bootstrap context as parent
+		assertThat(parent.getParent()).isNotNull();
+
+		ConfigurableApplicationContext bootstrapContext = (ConfigurableApplicationContext) parent
+				.getParent();
+
+		// The Bootstrap Marker bean should be present
+		assertThat(bootstrapContext
+				.containsLocalBean(BootstrapMarkerConfiguration.MARKER_BEAN_NAME))
+						.isTrue();
+
+		// Bootstrap should be the root, there should be no other parent
+		assertThat(bootstrapContext.getParent()).isNull();
+	}
+
+	@Configuration
+	static class BasicConfiguration {
+	}
+
+	@Configuration
+	static class RootConfiguration {
+
+		@Bean
+		public String rootBean() {
+			return "rootBean";
+		}
+	}
+}