Add FailureAnalyzer for missing GrpcSecurity in servlet mode

spring-grpc-server-spring-boot-autoconfigure/src/main/java/org/springframework/boot/grpc/server/autoconfigure/GrpcSecurityInServletFailureAnalyzer.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2012-present 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.grpc.server.autoconfigure;
+
+import org.jspecify.annotations.Nullable;
+
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
+import org.springframework.boot.diagnostics.AbstractFailureAnalyzer;
+import org.springframework.boot.diagnostics.FailureAnalysis;
+import org.springframework.boot.diagnostics.FailureAnalyzer;
+import org.springframework.core.env.Environment;
+import org.springframework.grpc.server.security.GrpcSecurity;
+import org.springframework.util.ClassUtils;
+
+/**
+ * {@link FailureAnalyzer} for missing {@link GrpcSecurity} in servlet-based gRPC
+ * applications.
+ *
+ * @author Andrey Litvitski
+ */
+public class GrpcSecurityInServletFailureAnalyzer extends AbstractFailureAnalyzer<NoSuchBeanDefinitionException> {
+
+	private static final String GRPC_SECURITY_PATH = "org.springframework.grpc.server.security.GrpcSecurity";
+
+	private static final String GRPC_SERVLET_PATH = "io.grpc.servlet.jakarta.GrpcServlet";
+
+	private final Environment environment;
+
+	public GrpcSecurityInServletFailureAnalyzer(Environment environment) {
+		this.environment = environment;
+	}
+
+	@Override
+	protected @Nullable FailureAnalysis analyze(Throwable rootFailure, NoSuchBeanDefinitionException cause) {
+		if (!isMissingGrpcSecurity(cause) || !isActuallyServletMode()) {
+			return null;
+		}
+		return new FailureAnalysis(getDescription(), getAction(), cause);
+	}
+
+	private boolean isMissingGrpcSecurity(NoSuchBeanDefinitionException ex) {
+		Class<?> type = ex.getBeanType();
+		return type != null && GRPC_SECURITY_PATH.equals(type.getName());
+	}
+
+	private boolean isActuallyServletMode() {
+		boolean servletOnClassPath = ClassUtils.isPresent(GRPC_SERVLET_PATH, getClass().getClassLoader());
+		if (!servletOnClassPath) {
+			return false;
+		}
+		String servletPropertyName = "spring.grpc.server.servlet.enabled";
+		return this.environment.getProperty(servletPropertyName, Boolean.class, true);
+	}
+
+	private String getDescription() {
+		return """
+				GrpcSecurity is not available because this application is running the gRPC server in servlet mode (GrpcServlet).
+				""";
+	}
+
+	private String getAction() {
+		return """
+				Configure security using the standard Spring Security servlet configuration (SecurityFilterChain / HttpSecurity).
+				""";
+	}
+
+}

spring-grpc-server-spring-boot-autoconfigure/src/main/resources/META-INF/spring.factories

@@ -3,3 +3,6 @@ org.springframework.boot.grpc.server.autoconfigure.security.GrpcDisableCsrfHttpC
 
 org.springframework.boot.EnvironmentPostProcessor=\
 org.springframework.boot.grpc.server.autoconfigure.ServletEnvironmentPostProcessor
+
+org.springframework.boot.diagnostics.FailureAnalyzer=\
+org.springframework.boot.grpc.server.autoconfigure.GrpcSecurityInServletFailureAnalyzer

spring-grpc-server-spring-boot-autoconfigure/src/test/java/org/springframework/boot/grpc/server/autoconfigure/GrpcSecurityInServletFailureAnalyzerTests.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2012-present 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.grpc.server.autoconfigure;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
+import org.springframework.boot.diagnostics.FailureAnalysis;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.core.env.Environment;
+import org.springframework.grpc.server.security.GrpcSecurity;
+
+/**
+ * Tests for {@link GrpcSecurityInServletFailureAnalyzer}.
+ *
+ * @author Andrey Litvitski
+ */
+class GrpcSecurityInServletFailureAnalyzerTests {
+
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner();
+
+	@Test
+	void whenServletModeEnabledThenGrpcSecurityFailureIsAnalyzed() {
+		this.contextRunner.withPropertyValues("spring.grpc.server.servlet.enabled=true").run((context) -> {
+			Environment environment = context.getEnvironment();
+			GrpcSecurityInServletFailureAnalyzer analyzer = new GrpcSecurityInServletFailureAnalyzer(environment);
+			NoSuchBeanDefinitionException ex = new NoSuchBeanDefinitionException(GrpcSecurity.class);
+			FailureAnalysis analysis = analyzer.analyze(ex, ex);
+			assertThat(analysis).isNotNull();
+		});
+	}
+
+	@Test
+	void whenServletModeDefaultThenGrpcSecurityFailureIsAnalyzed() {
+		this.contextRunner.run((context) -> {
+			Environment environment = context.getEnvironment();
+			GrpcSecurityInServletFailureAnalyzer analyzer = new GrpcSecurityInServletFailureAnalyzer(environment);
+			NoSuchBeanDefinitionException ex = new NoSuchBeanDefinitionException(GrpcSecurity.class);
+			FailureAnalysis analysis = analyzer.analyze(ex, ex);
+			assertThat(analysis).isNotNull();
+		});
+	}
+
+	@Test
+	void whenServletModeDisabledThenGrpcSecurityFailureIsNotAnalyzed() {
+		this.contextRunner.withPropertyValues("spring.grpc.server.servlet.enabled=false").run((context) -> {
+			Environment environment = context.getEnvironment();
+			GrpcSecurityInServletFailureAnalyzer analyzer = new GrpcSecurityInServletFailureAnalyzer(environment);
+			NoSuchBeanDefinitionException ex = new NoSuchBeanDefinitionException(GrpcSecurity.class);
+			FailureAnalysis analysis = analyzer.analyze(ex, ex);
+			assertThat(analysis).isNull();
+		});
+	}
+
+}