gRPC server support for Micronaut (HTTP/2)

This project is inspired by the Spring boot starter for gRPC module and backed by the Java gRPC implementation.

Features

Configures and runs the embedded gRPC server
- Reason: Micronaut does not support HTTP/2 at the moment
Global and per service interceptors
Custom ServerBuilder configuration
Fast startup time

Usage

Dependencies

Artifacts are published to Maven Central.

Maven

<dependency>
  <groupId>com.enegate</groupId>
  <artifactId>micronaut-grpc-server</artifactId>
  <version>0.0.1</version>
</dependency>

Gradle

dependencies {
  compile 'com.enegate:micronaut-grpc-server:0.0.1'
}

gRPC server

Implementation

Prerequisite: Generate artifacts from your Protocol Buffer .proto definition files

Extract from an example .proto file:

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

message HelloRequest {
  string name = 1;
}

message HelloReply {
  string message = 1;
}

Annotate your server interface implementation with @com.enegate.micronaut.grpc.server.annotation.GrpcService

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

Configuration

Port

The default port for the grpc server is 8081.

If you want to change the port add the port property to your application.yml file

micronaut:
  grpc:
    port: 9876

Reflection

To enable the reflection service add the reflection property to your application.yml file

micronaut:
  grpc:
    reflection: true

Health check

To enable the health check service add the healthcheck property to your application.yml file

micronaut:
  grpc:
    healthcheck: true

Interceptor

Per Service

Annotate your interceptor implementation with @com.enegate.micronaut.grpc.server.annotation.GrpcInterceptor and implement Interface io.grpc.ServerInterceptor

@GrpcInterceptor
public class GreeterServiceInterceptor implements ServerInterceptor {
    @Override
    public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(ServerCall<ReqT, RespT> call, Metadata headers, ServerCallHandler<ReqT, RespT> next) {
        return next.startCall(call, headers);
    }
}

Add the interceptor to the array parameter interceptors of the @GrpcService annotation of your server interface implementation

@GrpcService(interceptors = {GreeterServiceInterceptor.class})
public class GreeterService extends GreeterGrpc.GreeterImplBase {
    @Override
    public void sayHello(HelloRequest request, StreamObserver<HelloReply> responseObserver) {
        HelloReply reply = HelloReply.newBuilder().setMessage("Hello " + request.getName()).build();
        responseObserver.onNext(reply);
        responseObserver.onCompleted();
    }
}

Global

Annotate your interceptor implementation with @com.enegate.micronaut.grpc.server.annotation.GrpcInterceptor and set the global parameter to true.

Implement Interface io.grpc.ServerInterceptor

@GrpcInterceptor(global = true)
public class GlobalInterceptor implements ServerInterceptor {
    @Override
    public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(ServerCall<ReqT, RespT> call, Metadata headers, ServerCallHandler<ReqT, RespT> next) {
        return next.startCall(call, headers);
    }
}

ServerBuilder

To configure TLS etc.

Annotate your interceptor implementation with @com.enegate.micronaut.grpc.server.annotation.GrpcInterceptor and implement Interface com.enegate.micronaut.grpc.server.GrpcServerBuilderInterceptor

@GrpcInterceptor
public class ExampleServerBuilderInterceptor implements GrpcServerBuilderInterceptor {
    @Override
    public void intercept(ServerBuilder serverBuilder) {
        // Configure TLS
        serverBuilder.useTransportSecurity(...);
    }
}

Examples

micronaut-grpc-example (Java)
micronaut-grpc-example-kotlin (Kotlin)

SpikeBlues/micronaut-grpc-server