Add SpringApplication.setRegisterShutdownHook

Add a setRegisterShutdownHook option to SpringApplication allowing the
shutdown hook to not be registered.

Also update SpringApplicationBuilder to automatically disable shutdown
hooks for child contexts.

Fixes gh-314

spring-boot/src/main/java/org/springframework/boot/SpringApplication.java

@@ -177,6 +177,8 @@ public class SpringApplication {
 
 	private boolean headless = true;
 
+	private boolean registerShutdownHook = true;
+
 	private List<ApplicationContextInitializer<?>> initializers;
 
 	private List<ApplicationListener<?>> listeners;
@@ -284,7 +286,9 @@ public class SpringApplication {
 
 			// Create, load, refresh and run the ApplicationContext
 			context = createApplicationContext();
-			context.registerShutdownHook();
+			if (this.registerShutdownHook) {
+				context.registerShutdownHook();
+			}
 			context.setEnvironment(environment);
 			postProcessApplicationContext(context);
 			applyInitializers(context);
@@ -669,6 +673,15 @@ public class SpringApplication {
 		this.headless = headless;
 	}
 
+	/**
+	 * Sets if the created {@link ApplicationContext} should have a shutdown hook
+	 * registered. Defaults to {@code true} to ensure that JVM shutdowns are handled
+	 * gracefully.
+	 */
+	public void setRegisterShutdownHook(boolean registerShutdownHook) {
+		this.registerShutdownHook = registerShutdownHook;
+	}
+
 	/**
 	 * Sets if the Spring banner should be displayed when the application runs. Defaults
 	 * to {@code true}.

spring-boot/src/main/java/org/springframework/boot/builder/SpringApplicationBuilder.java

@@ -79,6 +79,8 @@ public class SpringApplicationBuilder {
 
 	private Set<String> additionalProfiles = new LinkedHashSet<String>();
 
+	private boolean registerShutdownHookApplied;
+
 	public SpringApplicationBuilder(Object... sources) {
 		this.application = new SpringApplication(sources);
 	}
@@ -109,8 +111,11 @@ public class SpringApplicationBuilder {
 	public ConfigurableApplicationContext run(String... args) {
 
 		if (this.parent != null) {
-			// If there is a parent initialize it and make sure it is added to the current
-			// context
+			// If there is a parent don't register a shutdown hook
+			if (!this.registerShutdownHookApplied) {
+				this.application.setRegisterShutdownHook(false);
+			}
+			// initialize it and make sure it is added to the current context
 			initializers(new ParentContextApplicationContextInitializer(
 					this.parent.run(args)));
 		}
@@ -201,6 +206,7 @@ public class SpringApplicationBuilder {
 		this.parent.context = parent;
 		this.parent.running.set(true);
 		initializers(new ParentContextApplicationContextInitializer(parent));
+
 		return this;
 	}
 
@@ -300,6 +306,16 @@ public class SpringApplicationBuilder {
 		return this;
 	}
 
+	/**
+	 * Sets if the created {@link ApplicationContext} should have a shutdown hook
+	 * registered.
+	 */
+	public SpringApplicationBuilder registerShutdownHook(boolean registerShutdownHook) {
+		this.registerShutdownHookApplied = true;
+		this.application.setRegisterShutdownHook(registerShutdownHook);
+		return this;
+	}
+
 	/**
 	 * Fixes the main application class that is used to anchor the startup messages.
 	 * @param mainApplicationClass the class to use.

spring-boot/src/test/java/org/springframework/boot/SpringApplicationTests.java

@@ -393,6 +393,17 @@ public class SpringApplicationTests {
 		verify(applicationContext.getApplicationContext()).registerShutdownHook();
 	}
 
+	@Test
+	public void registerShutdownHookOff() throws Exception {
+		SpringApplication application = new SpringApplication(ExampleConfig.class);
+		application.setApplicationContextClass(SpyApplicationContext.class);
+		application.setRegisterShutdownHook(false);
+		this.context = application.run();
+		SpyApplicationContext applicationContext = (SpyApplicationContext) this.context;
+		verify(applicationContext.getApplicationContext(), never())
+				.registerShutdownHook();
+	}
+
 	@Test
 	public void headless() throws Exception {
 		TestSpringApplication application = new TestSpringApplication(ExampleConfig.class);

spring-boot/src/test/java/org/springframework/boot/builder/SpringApplicationBuilderTests.java

@@ -108,6 +108,21 @@ public class SpringApplicationBuilderTests {
 		this.context = application.run();
 		verify(((SpyApplicationContext) this.context).getApplicationContext()).setParent(
 				any(ApplicationContext.class));
+		assertThat(((SpyApplicationContext) this.context).getRegisteredShutdownHook(),
+				equalTo(false));
+	}
+
+	@Test
+	public void parentContextCreationWithChildShutdown() throws Exception {
+		SpringApplicationBuilder application = new SpringApplicationBuilder(
+				ChildConfig.class).contextClass(SpyApplicationContext.class)
+				.registerShutdownHook(true);
+		application.parent(ExampleConfig.class);
+		this.context = application.run();
+		verify(((SpyApplicationContext) this.context).getApplicationContext()).setParent(
+				any(ApplicationContext.class));
+		assertThat(((SpyApplicationContext) this.context).getRegisteredShutdownHook(),
+				equalTo(true));
 	}
 
 	@Test
@@ -143,6 +158,8 @@ public class SpringApplicationBuilderTests {
 		this.context = application.run();
 		verify(((SpyApplicationContext) this.context).getApplicationContext()).setParent(
 				any(ApplicationContext.class));
+		assertThat(((SpyApplicationContext) this.context).getRegisteredShutdownHook(),
+				equalTo(false));
 	}
 
 	@Test
@@ -216,8 +233,11 @@ public class SpringApplicationBuilderTests {
 	public static class SpyApplicationContext extends AnnotationConfigApplicationContext {
 
 		private final ConfigurableApplicationContext applicationContext = spy(new AnnotationConfigApplicationContext());
+
 		private ResourceLoader resourceLoader;
 
+		private boolean registeredShutdownHook;
+
 		@Override
 		public void setParent(ApplicationContext parent) {
 			this.applicationContext.setParent(parent);
@@ -237,5 +257,14 @@ public class SpringApplicationBuilderTests {
 			return this.resourceLoader;
 		}
 
+		@Override
+		public void registerShutdownHook() {
+			super.registerShutdownHook();
+			this.registeredShutdownHook = true;
+		}
+
+		public boolean getRegisteredShutdownHook() {
+			return this.registeredShutdownHook;
+		}
 	}
 }