spring-boot-starter-grpc

Spring boot starter for gRPC.

Basic codes are forked from grpc-spring-boot-starter

Provided Features

Integration gRPC with spring-boot-starter style

• Scan for gRPC service implement annotated with @GRpcService
• global and customer gRPC interceptors support
• gRPC service daemon runner
• TLS Configuration

Load balance support

• etcd & consul service register plugin
• HAProxy sample

Tutorial

• git clone the project
• run mvn clean package install to install jar to local
• then check the example project under spring-boot-starter-grpc-example folder

Usage

Implement and Run gRPC service

1. Define gRPC service with protobuf 3 format

service Greeter {
    rpc SayHello ( HelloRequest) returns (  HelloReply) {}
}

2. Generate gRPC-java code from the service defination files(*.proto)

mvn generate-sources

3. implement the gRPC service and annatation the service with @GRpcService

    @GRpcService
    public static class GreeterService extends  GreeterGrpc.GreeterImplBase{
        @Override
        public void sayHello(GreeterOuterClass.HelloRequest request, StreamObserver<GreeterOuterClass.HelloReply> responseObserver) {
            final GreeterOuterClass.HelloReply.Builder replyBuilder = GreeterOuterClass.HelloReply.newBuilder().setMessage("Hello " + request.getName());
            responseObserver.onNext(replyBuilder.build());
            responseObserver.onCompleted();
        }
    }

4. spring application context now will auto scan and run the gRPC service

Interceptors support

The starter supports the registration of two kinds of interceptors: Global and Per Service. + In both cases the interceptor has to implement io.grpc.ServerInterceptor interface.

• Per service

@GRpcService(interceptors = { LogInterceptor.class })
public  class GreeterService extends  GreeterGrpc.GreeterImplBase{
    // ommited
}

LogInterceptor will be instantiated via spring factory if there is bean of type LogInterceptor, or via no-args constructor otherwise.

• Global

@GRpcGlobalInterceptor
public  class MyInterceptor implements ServerInterceptor{
    // ommited
}

The annotation on java config factory method is also supported :

 @Configuration
 public class MyConfig{
     @Bean
     @GRpcGlobalInterceptor
     public  ServerInterceptor globalInterceptor(){
         return new ServerInterceptor(){
             @Override
             public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(ServerCall<ReqT, RespT> call, Metadata headers, ServerCallHandler<ReqT, RespT> next) {
                // your logic here
                 return next.startCall(call, headers);
             }
         };
     }
 }

The particular service also has the opportunity to disable the global interceptors :

@GRpcService(applyGlobalInterceptors = false)
public  class GreeterService extends  GreeterGrpc.GreeterImplBase{
    // ommited
}