GH-1138 Fix serverless web container initialization

Resolves #1138

Author: olegz

spring-cloud-function-adapters/spring-cloud-function-serverless-web/pom.xml

@@ -21,7 +21,7 @@
 			<groupId>org.springframework</groupId>
 			<artifactId>spring-webmvc</artifactId>
 		</dependency>
-		
+
 		<!-- -->
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
@@ -34,26 +34,31 @@
 			<scope>test</scope>
 		</dependency>
 		<!-- -->
-		
+
 		<dependency>
-		    <groupId>jakarta.servlet</groupId>
-		    <artifactId>jakarta.servlet-api</artifactId>
-		    <scope>provided</scope>
+			<groupId>jakarta.servlet</groupId>
+			<artifactId>jakarta.servlet-api</artifactId>
+			<scope>provided</scope>
 		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-test</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-freemarker</artifactId>
+			<scope>test</scope>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-web</artifactId>
 			<exclusions>
-                <exclusion>
-                    <groupId>org.springframework.boot</groupId>
-                    <artifactId>spring-boot-starter-tomcat</artifactId>
-                </exclusion>
-            </exclusions>
+				<exclusion>
+					<groupId>org.springframework.boot</groupId>
+					<artifactId>spring-boot-starter-tomcat</artifactId>
+				</exclusion>
+			</exclusions>
 			<scope>test</scope>
 		</dependency>
 	</dependencies>

spring-cloud-function-adapters/spring-cloud-function-serverless-web/src/main/java/org/springframework/cloud/function/serverless/web/ServerlessAutoConfiguration.java

@@ -22,7 +22,6 @@
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
-import org.springframework.boot.autoconfigure.web.servlet.DispatcherServletRegistrationBean;
 import org.springframework.boot.web.context.ConfigurableWebServerApplicationContext;
 import org.springframework.boot.web.server.WebServer;
 import org.springframework.boot.web.server.WebServerException;
@@ -67,16 +66,6 @@ public void stop() throws WebServerException {
 
 				@Override
 				public void start() throws WebServerException {
-					if (applicationContext instanceof ServletWebServerApplicationContext servletApplicationContet) {
-						DispatcherServlet dispatcher = applicationContext.getBean(DispatcherServlet.class);
-						try {
-							dispatcher.init(new ProxyServletConfig(servletApplicationContet.getServletContext()));
-							logger.info("Initalized DispatcherServlet");
-						}
-						catch (Exception e) {
-							throw new IllegalStateException("Faild to create Spring MVC DispatcherServlet proxy", e);
-						}
-					}
 				}
 
 				@Override
@@ -97,10 +86,18 @@ public void afterPropertiesSet() throws Exception {
 				logger.info("Configuring Serverless Web Container");
 				ServerlessServletContext servletContext = new ServerlessServletContext();
 				servletApplicationContet.setServletContext(servletContext);
-				for (ServletContextInitializer beans : new ServletContextInitializerBeans(this.applicationContext)) {
-					if (!(beans instanceof DispatcherServletRegistrationBean)) {
-						beans.onStartup(servletContext);
-					}
+				DispatcherServlet dispatcher = applicationContext.getBean(DispatcherServlet.class);
+				try {
+					logger.info("Initializing DispatcherServlet");
+					dispatcher.init(new ProxyServletConfig(servletApplicationContet.getServletContext()));
+					logger.info("Initalized DispatcherServlet");
+				}
+				catch (Exception e) {
+					throw new IllegalStateException("Faild to create Spring MVC DispatcherServlet proxy", e);
+				}
+				for (ServletContextInitializer initializer : new ServletContextInitializerBeans(this.applicationContext)) {
+					System.out.println("==> INITIALIZING  " + initializer);
+					initializer.onStartup(servletContext);
 				}
 			}
 		}

spring-cloud-function-adapters/spring-cloud-function-serverless-web/src/main/java/org/springframework/cloud/function/serverless/web/ServerlessMVC.java

@@ -29,6 +29,7 @@
 
 
 import jakarta.servlet.AsyncContext;
+import jakarta.servlet.DispatcherType;
 import jakarta.servlet.Filter;
 import jakarta.servlet.FilterChain;
 import jakarta.servlet.FilterConfig;
@@ -156,8 +157,6 @@ public void stop() {
 	 * @see org.springframework.test.web.servlet.result.MockMvcResultMatchers
 	 */
 	public void service(HttpServletRequest request, HttpServletResponse response) throws Exception {
-		//this.waitForContext();
-		//contextStartupLatch.await(this.initializatioinTimeout, TimeUnit.MILLISECONDS);
 		Assert.state(this.waitForContext(), "Failed to initialize Application within the specified time of " + this.initializatioinTimeout + " milliseconds. "
 				+ "If you need to increase it, please set " + INIT_TIMEOUT + " environment variable");
 		this.service(request, response, (CountDownLatch) null);
@@ -269,6 +268,10 @@ public void doFilter(ServletRequest request, ServletResponse response) throws IO
 
 			this.request = request;
 			this.response = response;
+
+			if (!response.isCommitted() && request.getDispatcherType() != DispatcherType.ASYNC) {
+				response.flushBuffer();
+			}
 		}
 
 		/**

spring-cloud-function-adapters/spring-cloud-function-serverless-web/src/test/java/org/springframework/cloud/function/serverless/web/RequestResponseTests.java

@@ -57,6 +57,14 @@ public void after() {
 		this.mvc.stop();
 	}
 
+	@Test
+	public void validateFreemarker() throws Exception {
+		HttpServletRequest request = new ServerlessHttpServletRequest(null, "GET", "/index");
+		ServerlessHttpServletResponse response = new ServerlessHttpServletResponse();
+		mvc.service(request, response);
+		assertThat(response.getContentAsString()).contains("<h1> hello from freemarker </h1>");
+	}
+
 	@Test
 	public void validateAccessDeniedWithCustomHandler() throws Exception {
 		HttpServletRequest request = new ServerlessHttpServletRequest(null, "GET", "/foo/deny");

spring-cloud-function-adapters/spring-cloud-function-serverless-web/src/test/java/org/springframework/cloud/function/test/app/PetStoreSpringAppConfig.java

@@ -53,7 +53,7 @@
 
 
 @Configuration
-@Import({ PetsController.class })
+@Import({ PetsController.class, FreemarkerController.class })
 @EnableWebSecurity
 @EnableAutoConfiguration
 public class PetStoreSpringAppConfig {

spring-cloud-function-adapters/spring-cloud-function-serverless-web/src/test/resources/templates/index.ftlh

@@ -0,0 +1,5 @@
+<h1> hello from freemarker </h1>
+
+<#list 1..10 as x>
+    ${x}
+</#list>