Add client interceptor filter support

This allows a user to define a ClientInterceptorFilter bean
that decides which client interceptors to apply to which
GrpcChannelFactory.

Resolves #195

Signed-off-by: Andrey Litvitski <[email protected]>

Author: therepanic

spring-grpc-core/src/main/java/org/springframework/grpc/client/ClientInterceptorFilter.java

@@ -0,0 +1,39 @@
+/*
+ * 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.client;
+
+import io.grpc.ClientInterceptor;
+
+/**
+ * Strategy to determine whether a {@link ClientInterceptor} should be included for a
+ * given {@link GrpcChannelFactory}.
+ *
+ * @author Andrey Litvitski
+ */
+@FunctionalInterface
+public interface ClientInterceptorFilter {
+
+	/**
+	 * Determine whether the given {@link ClientInterceptor} should be included for the
+	 * provided {@link GrpcChannelFactory}.
+	 * @param interceptor the client interceptor under consideration.
+	 * @param channelFactory the channel factory in use.
+	 * @return {@code true} if the interceptor should be included; {@code false}
+	 * otherwise.
+	 */
+	boolean filter(ClientInterceptor interceptor, GrpcChannelFactory channelFactory);
+
+}

spring-grpc-core/src/main/java/org/springframework/grpc/client/ClientInterceptorsConfigurer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2024-2024 the original author or authors.
+ * 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.
@@ -21,6 +21,7 @@
 import java.util.List;
 
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.context.ApplicationContext;
 import org.springframework.grpc.internal.ApplicationContextBeanLookupUtils;
 
@@ -31,13 +32,16 @@
  * Configure a {@link ManagedChannelBuilder} with client interceptors.
  *
  * @author Chris Bono
+ * @author Andrey Litvitski
  */
 public class ClientInterceptorsConfigurer implements InitializingBean {
 
 	private final ApplicationContext applicationContext;
 
 	private List<ClientInterceptor> globalInterceptors;
 
+	private ClientInterceptorFilter interceptorFilter;
+
 	public ClientInterceptorsConfigurer(ApplicationContext applicationContext) {
 		this.applicationContext = applicationContext;
 	}
@@ -48,13 +52,18 @@ public ClientInterceptorsConfigurer(ApplicationContext applicationContext) {
 	 * @param interceptors the non-null list of interceptors to be applied to the channel
 	 * @param mergeWithGlobalInterceptors whether the provided interceptors should be
 	 * blended with the global interceptors.
+	 * @param factory the channel factory used to filter global interceptors
 	 */
 	protected void configureInterceptors(ManagedChannelBuilder<?> builder, List<ClientInterceptor> interceptors,
-			boolean mergeWithGlobalInterceptors) {
+			boolean mergeWithGlobalInterceptors, GrpcChannelFactory factory) {
 		// Add global interceptors first
 		List<ClientInterceptor> allInterceptors = new ArrayList<>(this.globalInterceptors);
 		// Add specific interceptors
 		allInterceptors.addAll(interceptors);
+		// Filter all interceptors
+		if (this.interceptorFilter != null) {
+			allInterceptors.removeIf(interceptor -> !this.interceptorFilter.filter(interceptor, factory));
+		}
 		if (mergeWithGlobalInterceptors) {
 			ApplicationContextBeanLookupUtils.sortBeansIncludingOrderAnnotation(this.applicationContext,
 					ClientInterceptor.class, allInterceptors);
@@ -66,11 +75,21 @@ protected void configureInterceptors(ManagedChannelBuilder<?> builder, List<Clie
 	@Override
 	public void afterPropertiesSet() {
 		this.globalInterceptors = findGlobalInterceptors();
+		this.interceptorFilter = findInterceptorFilter();
 	}
 
 	private List<ClientInterceptor> findGlobalInterceptors() {
 		return ApplicationContextBeanLookupUtils.getBeansWithAnnotation(this.applicationContext,
 				ClientInterceptor.class, GlobalClientInterceptor.class);
 	}
 
+	private ClientInterceptorFilter findInterceptorFilter() {
+		try {
+			return this.applicationContext.getBean(ClientInterceptorFilter.class);
+		}
+		catch (NoSuchBeanDefinitionException ignored) {
+			return null;
+		}
+	}
+
 }

spring-grpc-core/src/main/java/org/springframework/grpc/client/DefaultGrpcChannelFactory.java

@@ -96,7 +96,7 @@ public ManagedChannel createChannel(String target, ChannelBuilderOptions options
 		T builder = newChannelBuilder(targetUri, this.credentials.getChannelCredentials(target));
 		// Handle interceptors
 		this.interceptorsConfigurer.configureInterceptors(builder, options.interceptors(),
-				options.mergeWithGlobalInterceptors());
+				options.mergeWithGlobalInterceptors(), this);
 		// Handle customizers
 		this.globalCustomizers.forEach((c) -> c.customize(target, builder));
 		var customizer = options.<T>customizer();

spring-grpc-core/src/test/java/org/springframework/grpc/client/ClientInterceptorsConfigurerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 the original author or authors.
+ * 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.
@@ -43,6 +43,7 @@
  * Tests for {@link ClientInterceptorsConfigurer}.
  *
  * @author Chris Bono
+ * @author Andrey Litvitski
  */
 class ClientInterceptorsConfigurerTests {
 
@@ -67,8 +68,9 @@ private void customizeContextAndRunConfigurer(
 			List<ClientInterceptor> clientSpecificInterceptors, List<ClientInterceptor> expectedInterceptors) {
 		ManagedChannelBuilder<?> builder = Mockito.mock();
 		this.contextRunner().with(contextCustomizer).run((context) -> {
+			var factory = Mockito.mock(GrpcChannelFactory.class);
 			var configurer = context.getBean(ClientInterceptorsConfigurer.class);
-			configurer.configureInterceptors(builder, clientSpecificInterceptors, true);
+			configurer.configureInterceptors(builder, clientSpecificInterceptors, true, factory);
 			// NOTE: the interceptors are called in reverse order per builder contract
 			var expectedInterceptorsReversed = new ArrayList<>(expectedInterceptors);
 			Collections.reverse(expectedInterceptorsReversed);
@@ -129,13 +131,14 @@ void whenBlendInterceptorsFalseThenGlobalInterceptorsAddedFirst() {
 			ClientInterceptorsConfigurerTests.this.contextRunner()
 				.withUserConfiguration(GlobalClientInterceptorsConfig.class, ClientSpecificInterceptorsConfig.class)
 				.run((context) -> {
+					var factory = Mockito.mock(GrpcChannelFactory.class);
 					var interceptorA = context.getBean("interceptorA", ClientInterceptor.class);
 					var interceptorB = context.getBean("interceptorB", ClientInterceptor.class);
 					var clientSpecificInterceptors = List.of(interceptorB, interceptorA);
 					var expectedInterceptors = List.of(GlobalClientInterceptorsConfig.GLOBAL_INTERCEPTOR_BAR,
 							GlobalClientInterceptorsConfig.GLOBAL_INTERCEPTOR_FOO, interceptorB, interceptorA);
 					var configurer = context.getBean(ClientInterceptorsConfigurer.class);
-					configurer.configureInterceptors(builder, clientSpecificInterceptors, false);
+					configurer.configureInterceptors(builder, clientSpecificInterceptors, false, factory);
 					// NOTE: the interceptors are called in reverse order per builder
 					// contract
 					var expectedInterceptorsReversed = new ArrayList<>(expectedInterceptors);
@@ -151,13 +154,55 @@ void whenBlendInterceptorsTrueThenGlobalInterceptorsBlended() {
 			ClientInterceptorsConfigurerTests.this.contextRunner()
 				.withUserConfiguration(GlobalClientInterceptorsConfig.class, ClientSpecificInterceptorsConfig.class)
 				.run((context) -> {
+					var factory = Mockito.mock(GrpcChannelFactory.class);
 					var interceptorA = context.getBean("interceptorA", ClientInterceptor.class);
 					var interceptorB = context.getBean("interceptorB", ClientInterceptor.class);
 					var clientSpecificInterceptors = List.of(interceptorB, interceptorA);
 					var expectedInterceptors = List.of(GlobalClientInterceptorsConfig.GLOBAL_INTERCEPTOR_BAR,
 							interceptorB, GlobalClientInterceptorsConfig.GLOBAL_INTERCEPTOR_FOO, interceptorA);
 					var configurer = context.getBean(ClientInterceptorsConfigurer.class);
-					configurer.configureInterceptors(builder, clientSpecificInterceptors, true);
+					configurer.configureInterceptors(builder, clientSpecificInterceptors, true, factory);
+					// NOTE: the interceptors are called in reverse order per builder
+					// contract
+					var expectedInterceptorsReversed = new ArrayList<>(expectedInterceptors);
+					Collections.reverse(expectedInterceptorsReversed);
+					verify(builder).intercept(expectedInterceptorsReversed);
+				});
+		}
+
+	}
+
+	@Nested
+	class WithInterceptorFilters {
+
+		@Test
+		void whenFilterExcludesOneGlobalInterceptor_thenBuilderGetsOnlyAllowedOnes() {
+			ManagedChannelBuilder<?> builder = Mockito.mock();
+			ClientInterceptorsConfigurerTests.this.contextRunner()
+				.withUserConfiguration(GlobalClientInterceptorsConfig.class)
+				.withBean(ClientInterceptorFilter.class,
+						() -> (interceptor, __) -> interceptor == GlobalClientInterceptorsConfig.GLOBAL_INTERCEPTOR_BAR)
+				.run(context -> {
+					var factory = Mockito.mock(GrpcChannelFactory.class);
+					var configurer = context.getBean(ClientInterceptorsConfigurer.class);
+					configurer.configureInterceptors(builder, List.of(), true, factory);
+					var expectedInterceptors = List.of(GlobalClientInterceptorsConfig.GLOBAL_INTERCEPTOR_BAR);
+					verify(builder).intercept(expectedInterceptors);
+				});
+		}
+
+		@Test
+		void whenFilterIncludesAllGlobalInterceptors_thenBuilderGetsOnlyAllowedOnes() {
+			ManagedChannelBuilder<?> builder = Mockito.mock();
+			ClientInterceptorsConfigurerTests.this.contextRunner()
+				.withUserConfiguration(GlobalClientInterceptorsConfig.class)
+				.withBean(ClientInterceptorFilter.class, () -> (interceptor, __) -> true)
+				.run(context -> {
+					var factory = Mockito.mock(GrpcChannelFactory.class);
+					var configurer = context.getBean(ClientInterceptorsConfigurer.class);
+					configurer.configureInterceptors(builder, List.of(), true, factory);
+					var expectedInterceptors = List.of(GlobalClientInterceptorsConfig.GLOBAL_INTERCEPTOR_BAR,
+							GlobalClientInterceptorsConfig.GLOBAL_INTERCEPTOR_FOO);
 					// NOTE: the interceptors are called in reverse order per builder
 					// contract
 					var expectedInterceptorsReversed = new ArrayList<>(expectedInterceptors);

spring-grpc-core/src/test/java/org/springframework/grpc/client/GrpcChannelFactoryTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 the original author or authors.
+ * 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.
@@ -110,7 +110,7 @@ void whenOptionsContainNoInterceptorThenConfigurerInvokedWithNoInterceptor() {
 			channel = channelFactory.createChannel(channelName);
 			assertThat(channel).isNotNull();
 			verify(configurer).configureInterceptors(any(ManagedChannelBuilder.class),
-					assertArg((interceptors) -> assertThat(interceptors).isEmpty()), eq(false));
+					assertArg((interceptors) -> assertThat(interceptors).isEmpty()), eq(false), eq(channelFactory));
 		}
 
 		@Test
@@ -126,7 +126,8 @@ void whenOptionsContainInterceptorThenConfigurerInvokedWithInterceptor() {
 						.withInterceptorsMerge(true));
 			assertThat(channel).isNotNull();
 			verify(configurer).configureInterceptors(any(ManagedChannelBuilder.class),
-					assertArg((interceptors) -> assertThat(interceptors).containsExactly(interceptor)), eq(true));
+					assertArg((interceptors) -> assertThat(interceptors).containsExactly(interceptor)), eq(true),
+					eq(channelFactory));
 		}
 
 	}