Grpc server injection (#2208)

* plugin: update grpc server readme

* plugin: refactor gprc server test

This is a no-op change to enable test logic reuse for different
combinations.

* plugin: grpc server test Init after New

* plugin: allow grpc.Server to be injected

plugins/server/grpc/README.md

@@ -1,6 +1,6 @@
 # GRPC Server
 
-The grpc server is a [micro.Server](https://godoc.org/github.com/micro/go-micro/server#Server) compatible server.
+The grpc server is a [micro.Server](https://pkg.go.dev/github.com/asim/go-micro/server#Server) compatible server.
 
 ## Overview
 
@@ -13,8 +13,8 @@ Specify the server to your micro service
 
 ```go
 import (
-        "github.com/micro/go-micro"
-        "github.com/micro/go-plugins/server/grpc"
+        "github.com/asim/go-micro/v3"
+        "github.com/asim/go-micro/plugins/server/grpc/v3"
 )
 
 func main() {

plugins/server/grpc/grpc.go

@@ -119,10 +119,23 @@ func (g *grpcServer) configure(opts ...server.Option) {
 		return
 	}
 
+	// Optionally use injected grpc.Server if there's a one
+	var srv *grpc.Server
+	if srv = g.getGrpcServer(); srv != nil {
+		g.srv = srv
+	}
+
 	for _, o := range opts {
 		o(&g.opts)
 	}
 
+	g.rsvc = nil
+
+	// NOTE: injected grpc.Server doesn't have g.handler registered
+	if srv != nil {
+		return
+	}
+
 	maxMsgSize := g.getMaxMsgSize()
 
 	gopts := []grpc.ServerOption{
@@ -139,7 +152,6 @@ func (g *grpcServer) configure(opts ...server.Option) {
 		gopts = append(gopts, opts...)
 	}
 
-	g.rsvc = nil
 	g.srv = grpc.NewServer(gopts...)
 }
 
@@ -188,6 +200,18 @@ func (g *grpcServer) getListener() net.Listener {
 	return nil
 }
 
+func (g *grpcServer) getGrpcServer() *grpc.Server {
+	if g.opts.Context == nil {
+		return nil
+	}
+
+	if srv, ok := g.opts.Context.Value(grpcServerKey{}).(*grpc.Server); ok && srv != nil {
+		return srv
+	}
+
+	return nil
+}
+
 func (g *grpcServer) handler(srv interface{}, stream grpc.ServerStream) error {
 	if g.wg != nil {
 		g.wg.Add(1)

plugins/server/grpc/grpc_test.go

@@ -5,19 +5,23 @@ import (
 	"fmt"
 	"testing"
 
-	"github.com/asim/go-micro/v3"
-	bmemory "github.com/asim/go-micro/plugins/broker/memory/v3"
-	"github.com/asim/go-micro/v3/client"
-	gcli "github.com/asim/go-micro/plugins/client/grpc/v3"
-	"github.com/asim/go-micro/v3/errors"
-	rmemory "github.com/asim/go-micro/plugins/registry/memory/v3"
-	"github.com/asim/go-micro/v3/server"
-	gsrv "github.com/asim/go-micro/plugins/server/grpc/v3"
-	tgrpc "github.com/asim/go-micro/plugins/transport/grpc/v3"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/status"
 
+	"github.com/asim/go-micro/v3"
+	"github.com/asim/go-micro/v3/broker"
+	"github.com/asim/go-micro/v3/client"
+	"github.com/asim/go-micro/v3/errors"
+	"github.com/asim/go-micro/v3/registry"
+	"github.com/asim/go-micro/v3/server"
+	"github.com/asim/go-micro/v3/transport"
+
+	bmemory "github.com/asim/go-micro/plugins/broker/memory/v3"
+	gcli "github.com/asim/go-micro/plugins/client/grpc/v3"
+	rmemory "github.com/asim/go-micro/plugins/registry/memory/v3"
+	gsrv "github.com/asim/go-micro/plugins/server/grpc/v3"
 	pb "github.com/asim/go-micro/plugins/server/grpc/v3/proto"
+	tgrpc "github.com/asim/go-micro/plugins/transport/grpc/v3"
 )
 
 // server is used to implement helloworld.GreeterServer.
@@ -106,21 +110,7 @@ func BenchmarkServer(b *testing.B) {
 
 }
 */
-func TestGRPCServer(t *testing.T) {
-	r := rmemory.NewRegistry()
-	b := bmemory.NewBroker()
-	tr := tgrpc.NewTransport()
-	s := gsrv.NewServer(
-		server.Broker(b),
-		server.Name("foo"),
-		server.Registry(r),
-		server.Transport(tr),
-	)
-	c := gcli.NewClient(
-		client.Registry(r),
-		client.Broker(b),
-		client.Transport(tr),
-	)
+func testGRPCServer(t *testing.T, s server.Server, c client.Client, r registry.Registry, testRPC bool) {
 	ctx := context.TODO()
 
 	h := &testServer{}
@@ -165,6 +155,10 @@ func TestGRPCServer(t *testing.T) {
 		t.Fatal("this must return error, as we return error from handler")
 	}
 
+	if !testRPC {
+		return
+	}
+
 	cc, err := grpc.Dial(s.Options().Address, grpc.WithInsecure())
 	if err != nil {
 		t.Fatalf("failed to dial server: %v", err)
@@ -201,3 +195,63 @@ func TestGRPCServer(t *testing.T) {
 		}
 	}
 }
+
+func getTestHarness() (registry.Registry, broker.Broker, transport.Transport) {
+	r := rmemory.NewRegistry()
+	b := bmemory.NewBroker()
+	tr := tgrpc.NewTransport()
+	return r, b, tr
+}
+
+func TestGRPCServer(t *testing.T) {
+	r, b, tr := getTestHarness()
+	s := gsrv.NewServer(
+		server.Broker(b),
+		server.Name("foo"),
+		server.Registry(r),
+		server.Transport(tr),
+	)
+	c := gcli.NewClient(
+		client.Registry(r),
+		client.Broker(b),
+		client.Transport(tr),
+	)
+	testGRPCServer(t, s, c, r, true)
+}
+
+func TestGRPCServerInitAfterNew(t *testing.T) {
+	r, b, tr := getTestHarness()
+	s := gsrv.NewServer()
+	s.Init(
+		server.Broker(b),
+		server.Name("foo"),
+		server.Registry(r),
+		server.Transport(tr),
+	)
+	c := gcli.NewClient(
+		client.Registry(r),
+		client.Broker(b),
+		client.Transport(tr),
+	)
+	testGRPCServer(t, s, c, r, true)
+}
+
+func TestGRPCServerInjectedServer(t *testing.T) {
+	r, b, tr := getTestHarness()
+	srv := grpc.NewServer()
+	s := gsrv.NewServer(
+		gsrv.Server(srv),
+	)
+	s.Init(
+		server.Broker(b),
+		server.Name("foo"),
+		server.Registry(r),
+		server.Transport(tr),
+	)
+	c := gcli.NewClient(
+		client.Registry(r),
+		client.Broker(b),
+		client.Transport(tr),
+	)
+	testGRPCServer(t, s, c, r, false)
+}

plugins/server/grpc/options.go

@@ -20,6 +20,7 @@ type netListener struct{}
 type maxMsgSizeKey struct{}
 type maxConnKey struct{}
 type tlsAuth struct{}
+type grpcServerKey struct{}
 
 // gRPC Codec to be used to encode/decode requests for a given content type
 func Codec(contentType string, c encoding.Codec) server.Option {
@@ -51,6 +52,14 @@ func Listener(l net.Listener) server.Option {
 	return setServerOption(netListener{}, l)
 }
 
+// Server specifies a *grpc.Server to use instead of the default
+// This is for rare use case where user need to expose grpc.Server for
+// customization. Please NOTE however user injected grpcServer doesn't support
+// server Handler abstraction
+func Server(srv *grpc.Server) server.Option {
+	return setServerOption(grpcServerKey{}, srv)
+}
+
 // Options to be used to configure gRPC options
 func Options(opts ...grpc.ServerOption) server.Option {
 	return setServerOption(grpcOptions{}, opts)