Allow filtering of global server interceptors

This commit adds support for filtering the server-side global interceptors.

Resolves #208

Signed-off-by: Chris Bono <[email protected]>

Author: onobc

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

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2024-2025 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.grpc.server;
+
+import io.grpc.Server;
+import io.grpc.ServerServiceDefinition;
+
+/**
+ * Marker interface for {@link GrpcServerFactory} that is to be handled by the servlet
+ * container.
+ *
+ * @author Chris Bono
+ */
+public class ServletGrpcServerFactory implements GrpcServerFactory {
+
+	/**
+	 * Default instance of marker interface.
+	 */
+	public static ServletGrpcServerFactory INSTANCE = new ServletGrpcServerFactory();
+
+	@Override
+	public Server createServer() {
+		throw new UnsupportedOperationException("Marker interface only");
+	}
+
+	@Override
+	public void addService(ServerServiceDefinition service) {
+		throw new UnsupportedOperationException("Marker interface only");
+	}
+
+}

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

@@ -20,10 +20,15 @@
 import java.util.List;
 
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
+import org.springframework.beans.factory.NoUniqueBeanDefinitionException;
 import org.springframework.context.ApplicationContext;
+import org.springframework.core.log.LogAccessor;
 import org.springframework.grpc.internal.ApplicationContextBeanLookupUtils;
 import org.springframework.grpc.server.GlobalServerInterceptor;
+import org.springframework.grpc.server.GrpcServerFactory;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 import io.grpc.BindableService;
 import io.grpc.ServerInterceptor;
@@ -38,37 +43,65 @@
  */
 public class DefaultGrpcServiceConfigurer implements GrpcServiceConfigurer, InitializingBean {
 
+	private final LogAccessor log = new LogAccessor(getClass());
+
 	private final ApplicationContext applicationContext;
 
 	private List<ServerInterceptor> globalInterceptors;
 
+	private ServerInterceptorFilter interceptorFilter;
+
 	public DefaultGrpcServiceConfigurer(ApplicationContext applicationContext) {
 		this.applicationContext = applicationContext;
 	}
 
 	@Override
 	public void afterPropertiesSet() {
 		this.globalInterceptors = findGlobalInterceptors();
+		this.interceptorFilter = findInterceptorFilter();
 	}
 
 	@Override
-	public ServerServiceDefinition configure(ServerServiceDefinitionSpec serviceDefinitionSpec) {
-		return bindInterceptors(serviceDefinitionSpec.service(), serviceDefinitionSpec.serviceInfo());
+	public ServerServiceDefinition configure(ServerServiceDefinitionSpec serviceSpec, GrpcServerFactory serverFactory) {
+		Assert.notNull(serviceSpec, () -> "serviceSpec must not be null");
+		Assert.notNull(serverFactory, () -> "serverFactory must not be null");
+		return bindInterceptors(serviceSpec.service(), serviceSpec.serviceInfo(), serverFactory);
 	}
 
 	private List<ServerInterceptor> findGlobalInterceptors() {
 		return ApplicationContextBeanLookupUtils.getBeansWithAnnotation(this.applicationContext,
 				ServerInterceptor.class, GlobalServerInterceptor.class);
 	}
 
+	private ServerInterceptorFilter findInterceptorFilter() {
+		try {
+			return this.applicationContext.getBean(ServerInterceptorFilter.class);
+		}
+		catch (NoUniqueBeanDefinitionException noUniqueBeanEx) {
+			this.log.warn(noUniqueBeanEx,
+					() -> "No unique ServerInterceptorFilter bean found. Consider defining a single bean or marking one as @Primary");
+			return null;
+		}
+		catch (NoSuchBeanDefinitionException ignored) {
+			this.log.debug(
+					() -> "No ServerInterceptorFilter bean found - filtering will not be applied to server interceptors.");
+			return null;
+		}
+	}
+
 	private ServerServiceDefinition bindInterceptors(BindableService bindableService,
-			@Nullable GrpcServiceInfo serviceInfo) {
+			@Nullable GrpcServiceInfo serviceInfo, GrpcServerFactory serverFactory) {
 		var serviceDef = bindableService.bindService();
+
+		// Add and filter global interceptors first
+		List<ServerInterceptor> allInterceptors = new ArrayList<>(this.globalInterceptors);
+		if (this.interceptorFilter != null) {
+			allInterceptors
+				.removeIf(interceptor -> !this.interceptorFilter.filter(interceptor, serviceDef, serverFactory));
+		}
 		if (serviceInfo == null) {
-			return ServerInterceptors.interceptForward(serviceDef, this.globalInterceptors);
+			return ServerInterceptors.interceptForward(serviceDef, allInterceptors);
 		}
-		// Add global interceptors first
-		List<ServerInterceptor> allInterceptors = new ArrayList<>(this.globalInterceptors);
 		// Add interceptors by type
 		Arrays.stream(serviceInfo.interceptors())
 			.forEachOrdered(

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

@@ -16,6 +16,8 @@
 
 package org.springframework.grpc.server.service;
 
+import org.springframework.grpc.server.GrpcServerFactory;
+
 import io.grpc.ServerServiceDefinition;
 
 /**
@@ -29,12 +31,14 @@
 public interface GrpcServiceConfigurer {
 
 	/**
-	 * Configure and bind a gRPC service spec resulting in a service definition that can
+	 * Configure and bind a gRPC server spec resulting in a service definition that can
 	 * then be added to a gRPC server.
 	 * @param serviceSpec the spec containing the info about the service
-	 * @return bound and configured service definition that is ready to be added to the
+	 * @param serverFactory the factory that provides the server that the service will be
+	 * added to
+	 * @return bound and configured service definition that is ready to be added to a
 	 * server
 	 */
-	ServerServiceDefinition configure(ServerServiceDefinitionSpec serviceSpec);
+	ServerServiceDefinition configure(ServerServiceDefinitionSpec serviceSpec, GrpcServerFactory serverFactory);
 
 }

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

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2023-2025 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.grpc.server.service;
+
+import org.springframework.grpc.server.GrpcServerFactory;
+
+import io.grpc.ServerInterceptor;
+import io.grpc.ServerServiceDefinition;
+
+/**
+ * Strategy to determine whether a global {@link ServerInterceptor server interceptor}
+ * should be applied to {@link ServerServiceDefinition gRPC service}.
+ *
+ * @author Chris Bono
+ */
+@FunctionalInterface
+public interface ServerInterceptorFilter {
+
+	/**
+	 * Determine whether an interceptor should be applied to a service when the service is
+	 * running on a server provided by the given server factory.
+	 * @param interceptor the server interceptor under consideration.
+	 * @param service the service being added.
+	 * @param serverFactory the server factory in use.
+	 * @return {@code true} if the interceptor should be included; {@code false}
+	 * otherwise.
+	 */
+	boolean filter(ServerInterceptor interceptor, ServerServiceDefinition service, GrpcServerFactory serverFactory);
+
+}