Add GrpcServiceDiscoverer to prepare for interceptors

spring-grpc-core/src/main/java/org/springframework/grpc/server/GrpcServiceDiscoverer.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2024-2024 The gRPC-Spring 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.grpc.server;
+
+import java.util.List;
+
+import io.grpc.ServerServiceDefinition;
+
+/**
+ * Discovers {@link ServerServiceDefinition gRPC services} to be provided by the server.
+ *
+ * @author Michael (yidongnan@gmail.com)
+ * @author Chris Bono
+ */
+@FunctionalInterface
+public interface GrpcServiceDiscoverer {
+
+	/**
+	 * Find gRPC services for the server to provide.
+	 * @return list of services to add to the server - empty when no services available
+	 */
+	List<ServerServiceDefinition> findServices();
+
+}

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

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2016-2023 The gRPC-Spring 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.grpc.autoconfigure.server;
+
+import java.util.List;
+
+import io.grpc.BindableService;
+import io.grpc.ServerServiceDefinition;
+
+import org.springframework.beans.factory.ObjectProvider;
+import org.springframework.grpc.server.GrpcServiceDiscoverer;
+
+/**
+ * The default {@link GrpcServiceDiscoverer} that finds all {@link BindableService} beans
+ * and configures and binds them.
+ *
+ * @author Michael (yidongnan@gmail.com)
+ * @author Chris Bono
+ */
+class DefaultGrpcServiceDiscoverer implements GrpcServiceDiscoverer {
+
+	private final ObjectProvider<BindableService> grpcServicesProvider;
+
+	DefaultGrpcServiceDiscoverer(ObjectProvider<BindableService> grpcServicesProvider) {
+		this.grpcServicesProvider = grpcServicesProvider;
+	}
+
+	@Override
+	public List<ServerServiceDefinition> findServices() {
+		return grpcServicesProvider.orderedStream().map(BindableService::bindService).toList();
+	}
+
+}

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

@@ -28,6 +28,7 @@
 import org.springframework.context.annotation.Import;
 import org.springframework.grpc.autoconfigure.common.codec.GrpcCodecConfiguration;
 import org.springframework.grpc.server.GrpcServerFactory;
+import org.springframework.grpc.server.GrpcServiceDiscoverer;
 import org.springframework.grpc.server.ServerBuilderCustomizer;
 import org.springframework.grpc.server.lifecycle.GrpcServerLifecycle;
 
@@ -69,4 +70,10 @@ ServerBuilderCustomizers serverBuilderCustomizers(ObjectProvider<ServerBuilderCu
 		return new ServerBuilderCustomizers(customizers.orderedStream().toList());
 	}
 
+	@ConditionalOnMissingBean
+	@Bean
+	GrpcServiceDiscoverer grpcServiceDiscoverer(ObjectProvider<BindableService> bindableServicesProvider) {
+		return new DefaultGrpcServiceDiscoverer(bindableServicesProvider);
+	}
+
 }

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

@@ -20,7 +20,6 @@
 
 import javax.net.ssl.KeyManagerFactory;
 
-import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
@@ -30,11 +29,11 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.grpc.server.GrpcServerFactory;
+import org.springframework.grpc.server.GrpcServiceDiscoverer;
 import org.springframework.grpc.server.NettyGrpcServerFactory;
 import org.springframework.grpc.server.ServerBuilderCustomizer;
 import org.springframework.grpc.server.ShadedNettyGrpcServerFactory;
 
-import io.grpc.BindableService;
 import io.grpc.CompressorRegistry;
 import io.grpc.DecompressorRegistry;
 import io.grpc.netty.NettyServerBuilder;
@@ -54,7 +53,7 @@ static class ShadedNettyServerFactoryConfiguration {
 
 		@Bean
 		ShadedNettyGrpcServerFactory shadedNettyGrpcServerFactory(GrpcServerProperties properties,
-				ObjectProvider<BindableService> grpcServicesProvider, ServerBuilderCustomizers serverBuilderCustomizers,
+				GrpcServiceDiscoverer grpcServicesDiscoverer, ServerBuilderCustomizers serverBuilderCustomizers,
 				SslBundles bundles) {
 			ShadedNettyServerFactoryPropertyMapper mapper = new ShadedNettyServerFactoryPropertyMapper(properties);
 			List<ServerBuilderCustomizer<io.grpc.netty.shaded.io.grpc.netty.NettyServerBuilder>> builderCustomizers = List
@@ -66,7 +65,7 @@ ShadedNettyGrpcServerFactory shadedNettyGrpcServerFactory(GrpcServerProperties p
 			}
 			ShadedNettyGrpcServerFactory factory = new ShadedNettyGrpcServerFactory(properties.getAddress(), keyManager,
 					builderCustomizers);
-			grpcServicesProvider.orderedStream().map(BindableService::bindService).forEach(factory::addService);
+			grpcServicesDiscoverer.findServices().forEach(factory::addService);
 			return factory;
 		}
 
@@ -94,7 +93,7 @@ static class NettyServerFactoryConfiguration {
 
 		@Bean
 		NettyGrpcServerFactory nettyGrpcServerFactory(GrpcServerProperties properties,
-				ObjectProvider<BindableService> grpcServicesProvider, ServerBuilderCustomizers serverBuilderCustomizers,
+				GrpcServiceDiscoverer grpcServicesDiscoverer, ServerBuilderCustomizers serverBuilderCustomizers,
 				SslBundles bundles) {
 			NettyServerFactoryPropertyMapper mapper = new NettyServerFactoryPropertyMapper(properties);
 			List<ServerBuilderCustomizer<NettyServerBuilder>> builderCustomizers = List
@@ -106,7 +105,7 @@ NettyGrpcServerFactory nettyGrpcServerFactory(GrpcServerProperties properties,
 			}
 			NettyGrpcServerFactory factory = new NettyGrpcServerFactory(properties.getAddress(), keyManager,
 					builderCustomizers);
-			grpcServicesProvider.orderedStream().map(BindableService::bindService).forEach(factory::addService);
+			grpcServicesDiscoverer.findServices().forEach(factory::addService);
 			return factory;
 		}
 

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

@@ -28,6 +28,7 @@
 import java.util.concurrent.TimeUnit;
 
 import org.assertj.core.api.InstanceOfAssertFactories;
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.mockito.InOrder;
 import org.mockito.MockedStatic;
@@ -41,6 +42,7 @@
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.annotation.Order;
 import org.springframework.grpc.server.GrpcServerFactory;
+import org.springframework.grpc.server.GrpcServiceDiscoverer;
 import org.springframework.grpc.server.NettyGrpcServerFactory;
 import org.springframework.grpc.server.ServerBuilderCustomizer;
 import org.springframework.grpc.server.ShadedNettyGrpcServerFactory;
@@ -60,10 +62,16 @@
  */
 class GrpcServerAutoConfigurationTests {
 
-	private ApplicationContextRunner contextRunner() {
-		BindableService service = mock();
-		ServerServiceDefinition serviceDefinition = ServerServiceDefinition.builder("my-service").build();
+	private final BindableService service = mock();
+
+	private final ServerServiceDefinition serviceDefinition = ServerServiceDefinition.builder("my-service").build();
+
+	@BeforeEach
+	void prepareForTest() {
 		when(service.bindService()).thenReturn(serviceDefinition);
+	}
+
+	private ApplicationContextRunner contextRunner() {
 		// NOTE: we use noop server lifecycle to avoid startup
 		return new ApplicationContextRunner()
 			.withConfiguration(AutoConfigurations.of(GrpcServerAutoConfiguration.class,
@@ -73,9 +81,6 @@ private ApplicationContextRunner contextRunner() {
 	}
 
 	private ApplicationContextRunner contextRunnerWithLifecyle() {
-		BindableService service = mock();
-		ServerServiceDefinition serviceDefinition = ServerServiceDefinition.builder("my-service").build();
-		when(service.bindService()).thenReturn(serviceDefinition);
 		// NOTE: we use noop server lifecycle to avoid startup
 		return new ApplicationContextRunner()
 			.withConfiguration(AutoConfigurations.of(GrpcServerAutoConfiguration.class,
@@ -111,6 +116,24 @@ void serverLifecycleAutoConfiguredAsExpected() {
 				.hasFieldOrPropertyWithValue("factory", context.getBean(GrpcServerFactory.class)));
 	}
 
+	@Test
+	void whenHasUserDefinedGrpcServiceDiscovererDoesNotAutoConfigureBean() {
+		GrpcServiceDiscoverer customGrpcServiceDiscoverer = mock(GrpcServiceDiscoverer.class);
+		this.contextRunnerWithLifecyle()
+			.withBean("customGrpcServiceDiscoverer", GrpcServiceDiscoverer.class, () -> customGrpcServiceDiscoverer)
+			.run((context) -> assertThat(context).getBean(GrpcServiceDiscoverer.class)
+				.isSameAs(customGrpcServiceDiscoverer));
+	}
+
+	@Test
+	void grpcServiceDiscovererAutoConfiguredAsExpected() {
+		this.contextRunnerWithLifecyle()
+			.run((context) -> assertThat(context).getBean(GrpcServiceDiscoverer.class)
+				.extracting(GrpcServiceDiscoverer::findServices,
+						InstanceOfAssertFactories.list(ServerServiceDefinition.class))
+				.containsExactly(this.serviceDefinition));
+	}
+
 	@Test
 	void whenHasUserDefinedServerBuilderCustomizersDoesNotAutoConfigureBean() {
 		ServerBuilderCustomizers customCustomizers = mock(ServerBuilderCustomizers.class);