Extension Points

ClientInterceptor

io.grpc.ClientInterceptor is an interceptor to intercept the lifecycle of a gRPC call on the client side.

Register a ClientInterceptor for all gRPC stubs:

@Component
public class LoggingClientInterceptor implements ClientInterceptor {
    private static final Logger log = LoggerFactory.getLogger(LoggingClientInterceptor.class);

    @Override
    public <ReqT, RespT> ClientCall<ReqT, RespT> interceptCall(MethodDescriptor<ReqT, RespT> method, CallOptions callOptions, Channel next) {
        return new ForwardingClientCall.SimpleForwardingClientCall<ReqT, RespT>(next.newCall(method, callOptions)) {
            @Override
            public void sendMessage(ReqT message) {
                log.info("Sending message: {}", message);
                super.sendMessage(message);
            }
        };
    }
}

Multiple ClientInterceptor will be called in the order defined by the Spring Bean's order, from smallest to largest.

GrpcChannelCustomizer

GrpcChannelCustomizer customize the Channel before it is created.

Register a GrpcChannelCustomizer to set the retry attempts for the gRPC channels:

@Component
public class RetryGrpcChannelCustomizer implements GrpcChannelCustomizer {
    @Override
    public void customize(GrpcClientProperties.Channel channelConfig, ManagedChannelBuilder<?> channelBuilder) {
        channelBuilder.enableRetry().maxRetryAttempts(3);
    }
}

Multiple GrpcChannelCustomizer will be called in the order defined by the Spring Bean's order, from smallest to largest.

Deep Customization

If you're not happy with the autoconfigured gRPC client bean, you can configure it using the Spring original approach (@Bean).

If you manually create the gRPC client bean, the autoconfigured gRPC client bean will not be created.

@Configuration
class GrpcClientConfiguration {
    @Bean
    public SimpleServiceGrpc.SimpleServiceBlockingStub simpleServiceBlockingStub() {
        var channel = ManagedChannelBuilder.forAddress("localhost", 9090)
                .usePlaintext()
                .build();
        return SimpleServiceGrpc.newBlockingStub(channel);
    }
}