Make sure container's started before connection details use it

Prior to this commit, a Testcontainer that was managed as a bean
would not have been started in time if it was accessed before
the bean factory's configuration had been frozen. A common way
for this to occur is when using JPA. The entity manager factory
bean is LoadTimeWeaverAware which causes it to be created before
configuration is frozen. Creating this bean requires the DataSource
which in turn requires the JdbcConnectionDetails and its JDBC URL.
Getting the JDBC URL From the connection details requires the
container hosting the SQL database to have been started.

This commit updates ContainerConnectionDetails, the super-class for
all Testcontainer-based ConnectionDetails implementations, to publish
an event when the Container is retrieved from the details. When this
event is published, TestcontainersLifecycleBeanPostProcessor
initializes all containers that are defined as beans.

Closes gh-40585

spring-boot-project/spring-boot-testcontainers/src/main/java/org/springframework/boot/testcontainers/lifecycle/BeforeTestcontainerUsedEvent.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2012-2024 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
+ *
+ *      https://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.testcontainers.lifecycle;
+
+import org.testcontainers.containers.Container;
+
+import org.springframework.context.ApplicationEvent;
+
+/**
+ * Event published just before a Testcontainers {@link Container} is used.
+ *
+ * @author Andy Wilkinson
+ * @since 3.2.6
+ */
+public class BeforeTestcontainerUsedEvent extends ApplicationEvent {
+
+	public BeforeTestcontainerUsedEvent(Object source) {
+		super(source);
+	}
+
+}

spring-boot-project/spring-boot-testcontainers/src/main/java/org/springframework/boot/testcontainers/lifecycle/TestcontainersLifecycleBeanPostProcessor.java

@@ -39,7 +39,6 @@ import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.BeanPostProcessor;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.beans.factory.config.DestructionAwareBeanPostProcessor;
-import org.springframework.boot.testcontainers.properties.BeforeTestcontainersPropertySuppliedEvent;
 import org.springframework.context.ApplicationListener;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
@@ -61,7 +60,7 @@ import org.springframework.core.log.LogMessage;
  */
 @Order(Ordered.LOWEST_PRECEDENCE)
 class TestcontainersLifecycleBeanPostProcessor
-		implements DestructionAwareBeanPostProcessor, ApplicationListener<BeforeTestcontainersPropertySuppliedEvent> {
+		implements DestructionAwareBeanPostProcessor, ApplicationListener<BeforeTestcontainerUsedEvent> {
 
 	private static final Log logger = LogFactory.getLog(TestcontainersLifecycleBeanPostProcessor.class);
 
@@ -80,7 +79,7 @@ class TestcontainersLifecycleBeanPostProcessor
 	}
 
 	@Override
-	public void onApplicationEvent(BeforeTestcontainersPropertySuppliedEvent event) {
+	public void onApplicationEvent(BeforeTestcontainerUsedEvent event) {
 		initializeContainers();
 	}
 

spring-boot-project/spring-boot-testcontainers/src/main/java/org/springframework/boot/testcontainers/properties/BeforeTestcontainersPropertySuppliedEvent.java

@@ -18,7 +18,7 @@ package org.springframework.boot.testcontainers.properties;
 
 import java.util.function.Supplier;
 
-import org.springframework.context.ApplicationEvent;
+import org.springframework.boot.testcontainers.lifecycle.BeforeTestcontainerUsedEvent;
 
 /**
  * Event published just before the {@link Supplier value supplier} of a
@@ -26,8 +26,10 @@ import org.springframework.context.ApplicationEvent;
  *
  * @author Phillip Webb
  * @since 3.2.2
+ * @deprecated since 3.2.6 in favor of {@link BeforeTestcontainerUsedEvent}
  */
-public class BeforeTestcontainersPropertySuppliedEvent extends ApplicationEvent {
+@Deprecated(since = "3.2.6", forRemoval = true)
+public class BeforeTestcontainersPropertySuppliedEvent extends BeforeTestcontainerUsedEvent {
 
 	private final String propertyName;
 

spring-boot-project/spring-boot-testcontainers/src/main/java/org/springframework/boot/testcontainers/properties/TestcontainersPropertySource.java

@@ -79,6 +79,7 @@ public class TestcontainersPropertySource extends EnumerablePropertySource<Map<S
 		return (valueSupplier != null) ? getProperty(name, valueSupplier) : null;
 	}
 
+	@SuppressWarnings({ "removal", "deprecation" })
 	private Object getProperty(String name, Supplier<Object> valueSupplier) {
 		BeforeTestcontainersPropertySuppliedEvent event = new BeforeTestcontainersPropertySuppliedEvent(this, name);
 		this.eventPublishers.forEach((eventPublisher) -> eventPublisher.publishEvent(event));

spring-boot-project/spring-boot-testcontainers/src/main/java/org/springframework/boot/testcontainers/service/connection/ContainerConnectionDetailsFactory.java

@@ -25,11 +25,16 @@ import org.testcontainers.containers.Container;
 
 import org.springframework.aot.hint.RuntimeHints;
 import org.springframework.aot.hint.RuntimeHintsRegistrar;
+import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.boot.autoconfigure.service.connection.ConnectionDetails;
 import org.springframework.boot.autoconfigure.service.connection.ConnectionDetailsFactory;
 import org.springframework.boot.origin.Origin;
 import org.springframework.boot.origin.OriginProvider;
+import org.springframework.boot.testcontainers.lifecycle.BeforeTestcontainerUsedEvent;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ApplicationContextAware;
+import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.io.support.SpringFactoriesLoader;
 import org.springframework.core.io.support.SpringFactoriesLoader.FailureHandler;
@@ -123,10 +128,12 @@ public abstract class ContainerConnectionDetailsFactory<C extends Container<?>,
 	 * @param <C> the container type
 	 */
 	protected static class ContainerConnectionDetails<C extends Container<?>>
-			implements ConnectionDetails, OriginProvider, InitializingBean {
+			implements ConnectionDetails, OriginProvider, InitializingBean, ApplicationContextAware {
 
 		private final ContainerConnectionSource<C> source;
 
+		private volatile ApplicationEventPublisher eventPublisher;
+
 		private volatile C container;
 
 		/**
@@ -151,6 +158,7 @@ public abstract class ContainerConnectionDetailsFactory<C extends Container<?>,
 		protected final C getContainer() {
 			Assert.state(this.container != null,
 					"Container cannot be obtained before the connection details bean has been initialized");
+			this.eventPublisher.publishEvent(new BeforeTestcontainerUsedEvent(this));
 			return this.container;
 		}
 
@@ -159,6 +167,11 @@ public abstract class ContainerConnectionDetailsFactory<C extends Container<?>,
 			return this.source.getOrigin();
 		}
 
+		@Override
+		public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
+			this.eventPublisher = applicationContext;
+		}
+
 	}
 
 	static class ContainerConnectionDetailsFactoriesRuntimeHints implements RuntimeHintsRegistrar {