Add failure analyzer for missing web factory bean

See gh-30358

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/reactive/context/ReactiveWebServerApplicationContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 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.
@@ -18,12 +18,14 @@ package org.springframework.boot.web.reactive.context;
 
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
+import org.springframework.boot.WebApplicationType;
 import org.springframework.boot.availability.AvailabilityChangeEvent;
 import org.springframework.boot.availability.ReadinessState;
 import org.springframework.boot.web.context.ConfigurableWebServerApplicationContext;
 import org.springframework.boot.web.context.WebServerGracefulShutdownLifecycle;
 import org.springframework.boot.web.reactive.server.ReactiveWebServerFactory;
 import org.springframework.boot.web.server.WebServer;
+import org.springframework.boot.web.server.context.MissingWebServerFactoryBeanException;
 import org.springframework.context.ApplicationContextException;
 import org.springframework.core.metrics.StartupStep;
 import org.springframework.http.server.reactive.HttpHandler;
@@ -105,8 +107,8 @@ public class ReactiveWebServerApplicationContext extends GenericReactiveWebAppli
 		// Use bean names so that we don't consider the hierarchy
 		String[] beanNames = getBeanFactory().getBeanNamesForType(ReactiveWebServerFactory.class);
 		if (beanNames.length == 0) {
-			throw new ApplicationContextException(
-					"Unable to start ReactiveWebApplicationContext due to missing ReactiveWebServerFactory bean.");
+			throw new MissingWebServerFactoryBeanException(this.getClass(), ReactiveWebServerFactory.class,
+					WebApplicationType.REACTIVE);
 		}
 		if (beanNames.length > 1) {
 			throw new ApplicationContextException("Unable to start ReactiveWebApplicationContext due to multiple "

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/server/context/MissingWebServerFactoryBeanException.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2012-2022 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.web.server.context;
+
+import org.springframework.boot.WebApplicationType;
+import org.springframework.context.ApplicationContextException;
+import org.springframework.lang.NonNull;
+
+/**
+ * Throws exception when web server factory bean is missing.
+ *
+ * @author Guirong Hu
+ * @since 2.7.0
+ */
+@SuppressWarnings("serial")
+public class MissingWebServerFactoryBeanException extends ApplicationContextException {
+
+	private final WebApplicationType webApplicationType;
+
+	/**
+	 * Create a new {@code MissingWebServerFactoryBeanException} with the given web
+	 * application context class and the given web server factory class and the given type
+	 * of web application.
+	 * @param webApplicationContextClass the web application context class
+	 * @param webServerFactoryClass the web server factory class
+	 * @param webApplicationType the type of web application
+	 */
+	public MissingWebServerFactoryBeanException(@NonNull Class<?> webApplicationContextClass,
+			@NonNull Class<?> webServerFactoryClass, @NonNull WebApplicationType webApplicationType) {
+		super(String.format("Unable to start %s due to missing %s bean.", webApplicationContextClass.getSimpleName(),
+				webServerFactoryClass.getSimpleName()));
+		this.webApplicationType = webApplicationType;
+	}
+
+	/**
+	 * Returns the type of web application that is being run.
+	 * @return the type of web application
+	 * @since 2.7.0
+	 */
+	public WebApplicationType getWebApplicationType() {
+		return this.webApplicationType;
+	}
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/server/context/MissingWebServerFactoryBeanFailureAnalyzer.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2012-2022 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.web.server.context;
+
+import org.springframework.boot.WebApplicationType;
+import org.springframework.boot.diagnostics.AbstractFailureAnalyzer;
+import org.springframework.boot.diagnostics.FailureAnalysis;
+import org.springframework.boot.diagnostics.FailureAnalyzer;
+import org.springframework.context.ApplicationContextException;
+
+/**
+ * A {@link FailureAnalyzer} that performs analysis of failures caused by an
+ * {@link MissingWebServerFactoryBeanException}.
+ *
+ * @author Guirong Hu
+ */
+class MissingWebServerFactoryBeanFailureAnalyzer extends AbstractFailureAnalyzer<ApplicationContextException> {
+
+	private static final String ACTION = "Check your application's dependencies on supported web servers "
+			+ "or configuration of web application type.";
+
+	@Override
+	protected FailureAnalysis analyze(Throwable rootFailure, ApplicationContextException cause) {
+		Throwable rootCause = cause.getCause();
+		if (rootCause instanceof MissingWebServerFactoryBeanException) {
+			WebApplicationType webApplicationType = ((MissingWebServerFactoryBeanException) rootCause)
+					.getWebApplicationType();
+			return new FailureAnalysis(String.format(
+					"Reason: The running web application is of type %s, but the dependent class is missing.",
+					webApplicationType.name().toLowerCase()), ACTION, cause);
+		}
+		return null;
+	}
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/server/context/package-info.java

@@ -0,0 +1,21 @@
+/*
+ * Copyright 2012-2022 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.
+ */
+
+/**
+ * Web server integrations with Spring's
+ * {@link org.springframework.context.ApplicationContext ApplicationContext}.
+ */
+package org.springframework.boot.web.server.context;

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/context/ServletWebServerApplicationContext.java

@@ -37,11 +37,13 @@ import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.beans.factory.config.Scope;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
+import org.springframework.boot.WebApplicationType;
 import org.springframework.boot.availability.AvailabilityChangeEvent;
 import org.springframework.boot.availability.ReadinessState;
 import org.springframework.boot.web.context.ConfigurableWebServerApplicationContext;
 import org.springframework.boot.web.context.WebServerGracefulShutdownLifecycle;
 import org.springframework.boot.web.server.WebServer;
+import org.springframework.boot.web.server.context.MissingWebServerFactoryBeanException;
 import org.springframework.boot.web.servlet.FilterRegistrationBean;
 import org.springframework.boot.web.servlet.ServletContextInitializer;
 import org.springframework.boot.web.servlet.ServletContextInitializerBeans;
@@ -207,8 +209,8 @@ public class ServletWebServerApplicationContext extends GenericWebApplicationCon
 		// Use bean names so that we don't consider the hierarchy
 		String[] beanNames = getBeanFactory().getBeanNamesForType(ServletWebServerFactory.class);
 		if (beanNames.length == 0) {
-			throw new ApplicationContextException("Unable to start ServletWebServerApplicationContext due to missing "
-					+ "ServletWebServerFactory bean.");
+			throw new MissingWebServerFactoryBeanException(this.getClass(), ServletWebServerFactory.class,
+					WebApplicationType.SERVLET);
 		}
 		if (beanNames.length > 1) {
 			throw new ApplicationContextException("Unable to start ServletWebServerApplicationContext due to multiple "

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

@@ -74,7 +74,8 @@ org.springframework.boot.diagnostics.analyzer.InvalidConfigurationPropertyNameFa
 org.springframework.boot.diagnostics.analyzer.InvalidConfigurationPropertyValueFailureAnalyzer,\
 org.springframework.boot.diagnostics.analyzer.PatternParseFailureAnalyzer,\
 org.springframework.boot.liquibase.LiquibaseChangelogMissingFailureAnalyzer,\
-org.springframework.boot.web.embedded.tomcat.ConnectorStartFailureAnalyzer
+org.springframework.boot.web.embedded.tomcat.ConnectorStartFailureAnalyzer,\
+org.springframework.boot.web.server.context.MissingWebServerFactoryBeanFailureAnalyzer
 
 # Failure Analysis Reporters
 org.springframework.boot.diagnostics.FailureAnalysisReporter=\

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/reactive/context/ReactiveWebServerApplicationContextTests.java

@@ -61,7 +61,7 @@ class ReactiveWebServerApplicationContextTests {
 	void whenThereIsNoWebServerFactoryBeanThenContextRefreshWillFail() {
 		assertThatExceptionOfType(ApplicationContextException.class).isThrownBy(() -> this.context.refresh())
 				.withMessageContaining(
-						"Unable to start ReactiveWebApplicationContext due to missing ReactiveWebServerFactory bean");
+						"Unable to start ReactiveWebServerApplicationContext due to missing ReactiveWebServerFactory bean");
 	}
 
 	@Test

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/server/context/MissingWebServerFactoryBeanFailureAnalyzerTests.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2012-2022 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.web.server.context;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.diagnostics.FailureAnalysis;
+import org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext;
+import org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext;
+import org.springframework.context.ApplicationContextException;
+import org.springframework.context.ConfigurableApplicationContext;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link MissingWebServerFactoryBeanFailureAnalyzer}.
+ *
+ * @author Guirong Hu
+ */
+class MissingWebServerFactoryBeanFailureAnalyzerTests {
+
+	@Test
+	void missingServletWebServerFactoryBeanFailure() {
+		ApplicationContextException failure = createFailure(new ServletWebServerApplicationContext());
+		assertThat(failure).isNotNull();
+		FailureAnalysis analysis = new MissingWebServerFactoryBeanFailureAnalyzer().analyze(failure);
+		assertThat(analysis).isNotNull();
+		assertThat(analysis.getDescription()).isEqualTo(
+				"Reason: The running web application is of type servlet, but the dependent class is missing.");
+		assertThat(analysis.getAction()).isEqualTo(
+				"Check your application's dependencies on supported web servers or configuration of web application type.");
+	}
+
+	@Test
+	void missingReactiveWebServerFactoryBeanFailure() {
+		ApplicationContextException failure = createFailure(new ReactiveWebServerApplicationContext());
+		FailureAnalysis analysis = new MissingWebServerFactoryBeanFailureAnalyzer().analyze(failure);
+		assertThat(analysis).isNotNull();
+		assertThat(analysis.getDescription()).isEqualTo(
+				"Reason: The running web application is of type reactive, but the dependent class is missing.");
+		assertThat(analysis.getAction()).isEqualTo(
+				"Check your application's dependencies on supported web servers or configuration of web application type.");
+	}
+
+	private ApplicationContextException createFailure(ConfigurableApplicationContext context) {
+		try {
+			context.refresh();
+			context.close();
+			return null;
+		}
+		catch (ApplicationContextException ex) {
+			return ex;
+		}
+	}
+
+}

src/checkstyle/import-control.xml

@@ -93,6 +93,9 @@
 		</subpackage>
 		<subpackage name="server">
 			<disallow pkg="org.springframework.context" />
+			<subpackage name="context">
+				<allow pkg="org.springframework.context" />
+			</subpackage>
 		</subpackage>
 		<subpackage name="context">
 			<allow pkg="org.springframework.boot.web.server" />