Ensure that DevTools' beans use eager init even when app is lazy

Closes gh-15870

Author: wilkinsona

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/autoconfigure/EagerInitializationAutoConfiguration.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2012-2019 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.boot.devtools.autoconfigure;
+
+import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.config.BeanDefinition;
+import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
+import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.context.annotation.Bean;
+import org.springframework.core.Ordered;
+
+/**
+ * {@link EnableAutoConfiguration Auto-configuration} to ensure that DevTools' beans are
+ * eagerly initialized when the application is otherwise being initialized lazily.
+ *
+ * @author Andy Wilkinson
+ * @since 2.2.0
+ */
+public class EagerInitializationAutoConfiguration {
+
+	@Bean
+	public static AlwaysEagerBeanFactoryPostProcessor alwaysEagerBeanFactoryPostProcessor() {
+		return new AlwaysEagerBeanFactoryPostProcessor();
+	}
+
+	private static final class AlwaysEagerBeanFactoryPostProcessor
+			implements BeanFactoryPostProcessor, Ordered {
+
+		@Override
+		public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)
+				throws BeansException {
+			for (String name : beanFactory.getBeanDefinitionNames()) {
+				BeanDefinition beanDefinition = beanFactory.getBeanDefinition(name);
+				String factoryBeanName = beanDefinition.getFactoryBeanName();
+				if (factoryBeanName != null && factoryBeanName
+						.startsWith("org.springframework.boot.devtools")) {
+					beanDefinition.setLazyInit(false);
+				}
+			}
+		}
+
+		@Override
+		public int getOrder() {
+			return Ordered.HIGHEST_PRECEDENCE + 1;
+		}
+
+	}
+
+}

spring-boot-project/spring-boot-devtools/src/main/resources/META-INF/spring.factories

@@ -9,6 +9,7 @@ org.springframework.boot.devtools.logger.DevToolsLogFactory.Listener
 
 # Auto Configure
 org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
+org.springframework.boot.devtools.autoconfigure.EagerInitializationAutoConfiguration,\
 org.springframework.boot.devtools.autoconfigure.DevToolsDataSourceAutoConfiguration,\
 org.springframework.boot.devtools.autoconfigure.LocalDevToolsAutoConfiguration,\
 org.springframework.boot.devtools.autoconfigure.RemoteDevToolsAutoConfiguration