dependency injection in grpc server go

Question

Suppose we have a go api containing a grpc server implementation.

This grpc server method has to do a variety of tasks which needs to be abstracted as a different service within the same api.

Is there a way to inject this new service in the grpc server?

Sample code:

package grpcserver

func (g *GrpcServer) GrpcServerExample(ctx context.Context, r *grpcpackage.SampleGrpcRequest) (*grpcpackage.SampleGrpcResponse, error) {
    service := differentService{}   //how to inject this instead of creating here
    result := service.DoSomething()
    return nil,nil
}

Answer 1

You can inject the service into GrpcServer while registering the gRPC server.

package grpcserver

type GrpcServer struct {
    MyService Service
}

func (g *GrpcServer) GrpcServerExample(ctx context.Context, r *grpcpackage.SampleGrpcRequest) (*grpcpackage.SampleGrpcResponse, error) {
    service := g.MyService
    result := service.DoSomething()
    return nil,nil
}

func main() {
    s := grpcpackage.NewServer()

    grpcpackage.RegisterGrpcServer(s, &GrpcServer{
        // Inject Here
        MyService: &ServiceImpl{},
    })
}

service_interface.go

package grpcserver

type Service interface {
    DoSomething() int
}

service_impl.go

package grpcserver

type ServiceImpl struct {
}

func (s *ServiceImpl) DoSomething() int {
    return 123
}