add goa examples

go/goa_example/cmd/host/grpc.go

@@ -0,0 +1,82 @@
+package main
+
+import (
+	"context"
+	pet_storepb "goa_example/gen/grpc/pet_store/pb"
+	petstoresvr "goa_example/gen/grpc/pet_store/server"
+	petstore "goa_example/gen/pet_store"
+	"log"
+	"net"
+	"net/url"
+	"sync"
+
+	grpcmiddleware "github.com/grpc-ecosystem/go-grpc-middleware"
+	grpcmdlwr "goa.design/goa/v3/grpc/middleware"
+	"goa.design/goa/v3/middleware"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/reflection"
+)
+
+// handleGRPCServer starts configures and starts a gRPC server on the given
+// URL. It shuts down the server if any error is received in the error channel.
+func handleGRPCServer(ctx context.Context, u *url.URL, petStoreEndpoints *petstore.Endpoints, wg *sync.WaitGroup, errc chan error, logger *log.Logger, debug bool) {
+
+	// Setup goa log adapter.
+	var (
+		adapter middleware.Logger
+	)
+	{
+		adapter = middleware.NewLogger(logger)
+	}
+
+	// Wrap the endpoints with the transport specific layers. The generated
+	// server packages contains code generated from the design which maps
+	// the service input and output data structures to gRPC requests and
+	// responses.
+	var (
+		petStoreServer *petstoresvr.Server
+	)
+	{
+		petStoreServer = petstoresvr.New(petStoreEndpoints, nil)
+	}
+
+	// Initialize gRPC server with the middleware.
+	srv := grpc.NewServer(
+		grpcmiddleware.WithUnaryServerChain(
+			grpcmdlwr.UnaryRequestID(),
+			grpcmdlwr.UnaryServerLog(adapter),
+		),
+	)
+
+	// Register the servers.
+	pet_storepb.RegisterPetStoreServer(srv, petStoreServer)
+
+	for svc, info := range srv.GetServiceInfo() {
+		for _, m := range info.Methods {
+			logger.Printf("serving gRPC method %s", svc+"/"+m.Name)
+		}
+	}
+
+	// Register the server reflection service on the server.
+	// See https://grpc.github.io/grpc/core/md_doc_server-reflection.html.
+	reflection.Register(srv)
+
+	(*wg).Add(1)
+	go func() {
+		defer (*wg).Done()
+
+		// Start gRPC server in a separate goroutine.
+		go func() {
+			lis, err := net.Listen("tcp", u.Host)
+			if err != nil {
+				errc <- err
+			}
+			logger.Printf("gRPC server listening on %q", u.Host)
+			errc <- srv.Serve(lis)
+		}()
+
+		<-ctx.Done()
+		logger.Printf("shutting down gRPC server at %q", u.Host)
+		srv.Stop()
+	}()
+}