I am creating a grpc service in go, I set up my grpc as follows
func setupGrpc() {
lis, err := net.Listen("tcp", ":9000")
if err != nil {
log.Fatalf("failed to listen: %v", err)
}
s := followerservice.UserServer{}
grpcServer := grpc.NewServer()
gen.RegisterUserServiceServer(grpcServer, &s)
// for ease of cli dev
reflection.Register(s) // this doesn't work!
if err := grpcServer.Serve(lis); err != nil {
log.Fatalf("failed to serve: %s", err)
}
}
My UserServer looks like this
type UserServer struct {
gen.UnimplementedUserServiceServer
}
func (s *UserServer) Create(ctx context.Context, in *gen.CreateUserRequest)(*gen.CreateUserResponse, error) {
log.Printf("Receive message body from client: %s", in.Email)
return &gen.CreateUserResponse{Id: "new id!"}, nil
}
At the line marked in func setupGrpc() I get a compile time error:
followerservice.UserServer does not implement reflection.GRPCServer (missing GetServiceInfo method)
but I can't find out how to implement it, I've been googling for hours now. It feels like protoc could generate this for me, but I'm kinda confused.
You have to reflection.Register the *grpc.Server that you got from the grpc.NewServer() constructor, not your own implementation.
grpcServer := grpc.NewServer()
gen.RegisterUserServiceServer(grpcServer, &s)
reflection.Register(grpcServer)
Related
I tried using the following code but the client hangs and never receives from the mock server.
I thought this part: Do(rs.EXPECT().Send(&proto.Response{Result: "steve"})would make the mock server response to the client, it never worked out.
For a server-streaming grpc mock, a typical approach like:
mockServer.EXPECT().FetchResponse(&proto.Request{Id: 123}, rs).Times(1).Return(...)
doesn't work, the return value is expected to be an error, not a streaming message.
Could someone with a kind heart please explain how this problem should be handled properly?
Code
func Test_Streaming(t *testing.T) {
// create listiner
lis, err := net.Listen("tcp", ":50005")
if err != nil {
log.Fatalf("failed to listen: %v", err)
}
// create grpc server
s := grpc.NewServer()
c := gomock.NewController(t)
mockServer := mock_proto.NewMockStreamServiceServer(c)
proto.RegisterStreamServiceServer(s, mockServer)
go func() {
log.Println("start server")
// and start...
if err := s.Serve(lis); err != nil {
log.Fatalf("failed to serve: %v", err)
}
}()
rs := mock_proto.NewMockStreamService_FetchResponseServer(c)
mockServer.EXPECT().FetchResponse(&proto.Request{Id: 123}, rs).Times(1).Do(rs.EXPECT().Send(&proto.Response{Result: "steve"}))
// client call FetchResponse
ClientConnect()
}
I am a new Go developer and I am trying to build a single project that has both a gRPC server and a Gin HTTP server. This is what my code roughly looks like:
package main
import (
"log"
"net"
"github.com/gin-gonic/gin"
"google.golang.org/grpc"
)
func main() {
startGRPCServer()
startHTTPServer()
}
func startGRPCServer() {
listener, err := net.Listen("tcp", ":9000")
if err != nil {
log.Fatalf("could not attach listener to port: %v", err)
}
s := grpc.NewServer()
if err := s.Serve(listener); err != nil {
log.Fatalf("could not start grpc server: %v", err)
}
}
func startHTTPServer() {
g := gin.Default()
if err := g.Run(":8000"); err != nil {
log.Fatalf("could not start http server: %v", err)
}
}
When I run the code above, only the gRPC server starts. The startHTTPServer() function doesn't even get invoked. When I switch the order of the calls (move startHTTPServer() above startGRPCServer()), the startGRPCServer() function never gets called. Why does this happen? How can I fix this so that both functions get called and both servers run?
The startGRPCServer function blocks on running the grpc server. Run the GRPC server in a goroutine so that startGRPCServer returns.
func startGRPCServer() {
listener, err := net.Listen("tcp", ":9000")
if err != nil {
log.Fatalf("could not attach listener to port: %v", err)
}
s := grpc.NewServer()
go func() {
if err := s.Serve(listener); err != nil {
log.Fatalf("could not start grpc server: %v", err)
}
}()
}
So I have the following:
type Node struct {
Table map[string]string
thing.UnimplementedGreeterServer
address string
}
func (n *Node) Start() {
lis, err := net.Listen("tcp", port)
if err != nil {
log.Fatalf("failed to listen: %v", err)
}
s := grpc.NewServer()
thing.RegisterGreeterServer(s, n)
if err := s.Serve(lis); err != nil {
log.Fatalf("failed to serve: %v", err)
}
}
In my main function I'll spin up mulitple nodes like so:
func main() {
n :=Node{Table: map[string]string{}}
go n.Start()
conn, err := grpc.Dial("localhost:50051", grpc.WithInsecure(), grpc.WithBlock())
}
The problem is, because I'm spinning up the node concurrently, there's a chance the dial up connection might not work because the node might not have been setup yet.
Ideally, I'd like a done channel that tells me when the grpc server has actually started listening. How do I accomplish this?
This is essntially the same problem as How to add hook on golang grpc server start? which doesn't have an answer
s.Serve(listener) blocks, so you can't achieve your purpose by having a done chan, instead you have to implement the healthcheck and readiness for your service, and check those before performing any request by the client.
The server should implement the following proto:
syntax = "proto3";
package grpc.health.v1;
message HealthCheckRequest {
string service = 1;
}
message HealthCheckResponse {
enum ServingStatus {
UNKNOWN = 0;
SERVING = 1;
NOT_SERVING = 2;
SERVICE_UNKNOWN = 3; // Used only by the Watch method.
}
ServingStatus status = 1;
}
service Health {
rpc Check(HealthCheckRequest) returns (HealthCheckResponse);
rpc Watch(HealthCheckRequest) returns (stream HealthCheckResponse);
}
For example, the envoy proxy grpc_health_check works with the above proto.
Read GRPC Health Checking Protocol for more information.
The server can be Dialed as soon as net.Listen returns a nil error. Dial will block until the server calls Accept (which will happen somewhere in s.Serve in this case).
Either move creation of the listener into the caller and pass it as an argument:
func (n *Node) Start(lis net.Listener) {
s := grpc.NewServer()
thing.RegisterGreeterServer(s, n)
if err := s.Serve(lis); err != nil {
log.Fatalf("failed to serve: %v", err)
}
}
func main() {
lis, err := net.Listen("tcp", port)
if err != nil {
log.Fatalf("failed to listen: %v", err)
}
n := Node{Table: map[string]string{}}
go n.Start(lis)
conn, err := grpc.Dial("localhost:50051", grpc.WithInsecure(), grpc.WithBlock())
}
Or signal that the listener is up after Listen returns:
func (n *Node) Start(up chan struct{}) {
lis, err := net.Listen("tcp", port)
if err != nil {
log.Fatalf("failed to listen: %v", err)
}
if up != nil {
close(up)
}
s := grpc.NewServer()
thing.RegisterGreeterServer(s, n)
if err := s.Serve(lis); err != nil {
log.Fatalf("failed to serve: %v", err)
}
}
func main() {
n := Node{Table: map[string]string{}}
up := make(chan struct{})
go n.Start(up)
<-up
conn, err := grpc.Dial("localhost:50051", grpc.WithInsecure(), grpc.WithBlock())
}
For all those who are still looking for an answer to this, here is another simple way to do it. Start the server in a child routine. Here is a code snippet:
// Start the server in a child routine
go func() {
if err := s.Serve(listener); err != nil {
log.Fatalf("Failed to serve: %v", err)
}
}()
fmt.Println("Server succesfully started on port :50051")
In my case I am using MongoDB as well, so when you run it, you get:
grpc-go-mongodb-cobra>go run server/main.go
Starting server on port :50051...
Connecting to MongoDB...
Connected to MongoDB
Server succesfully started on port :50051
I have also written a Blog post on this, with working code in GitHub. Here is the link: https://softwaredevelopercentral.blogspot.com/2021/03/golang-grpc-microservice.html
I'm trying to abstract the start of a GRPC server
The original main function is the following:
func main() {
lis, err := net.Listen("tcp", port)
if err != nil {
log.Fatalf("failed to listen: %v", err)
}
s := grpc.NewServer()
pb.RegisterCollectionServer(s, &server.Server{})
// Register reflection service on gRPC server.
reflection.Register(s)
if err := s.Serve(lis); err != nil {
log.Fatalf("failed to serve: %v", err)
}
}
My goal is to have something like this:
func startService(sr func(*grpc.Server, interface{}), srv interface{}) error {
lis, err := net.Listen("tcp", port)
if err != nil {
return err
}
s := grpc.NewServer()
sr(s, srv)
reflection.Register(s)
return s.Serve(lis)
}
func main() {
err := startService(pb.RegisterCollectionServer, &server.Server{})
if err != nil {
log.Fatalf("failed to start Service: %v", err)
}
}
But this gives me the following error:
cannot use collection_api.RegisterCollectionServer (type func(*grpc.Server, collection_api.CollectionServer)) as type func(*grpc.Server, interface {}) in argument to startServicego
It seems that collection_api.CollectionServer is not a valid interface{} type.
Any idea how to make this work?
In your setup the function signature of collector_api.RegisterCollectionServer must match exactly func(*grpc.Server, interface{}), there is no "is-kind-of" in Go as there is in other languages.
If you want to keep the startService function independent of the collection_api types, you can use a anonymous function in main(). If you know that you what ever you are registering is always dependent on the implementation of the anonymous function (in this case &server.Server{}), then you can leave this detail out of the function signature of startService and put it into the anonymous function:
func startService(sr func(*grpc.Server)) error {
lis, err := net.Listen("tcp", port)
if err != nil {
return err
}
s := grpc.NewServer()
sr(s)
reflection.Register(s)
return s.Serve(lis)
}
func main() {
err := startService(func(grpcServer *grpc.Server) {
pb.RegisterCollectionServer(grpcServer, &server.Server{})
}, &server.Server{})
if err != nil {
log.Fatalf("failed to start Service: %v", err)
}
}
I am trying to get the stackdriver tracer to work with gRPC and I need some help. I have been looking at these two links for reference and I still can't get it to work:
https://medium.com/#harlow/tracing-grpc-calls-in-golang-with-google-stackdriver-b22495763a06#.81oa9q21v
https://rakyll.org/grpc-trace/
For simplicity, I am just working with the hello world gRPC example. Here's my client:
func main() {
// Set up a connection to the server.
conn, err := grpc.Dial("localhost:50051", grpc.WithInsecure(), grpc.WithUnaryInterceptor(grpc.UnaryClientInterceptor(clientInterceptor)))
if err != nil {
log.Fatalf("did not connect: %v", err)
}
defer conn.Close()
c := pb.NewGreeterClient(conn)
ctx := context.Background()
tc, err := trace.NewClient(ctx, "{PROJECT-ID}")
if err != nil {
log.Fatal(err)
}
span := tc.NewSpan("/greeter/SayHello")
defer span.Finish()
ctx = trace.NewContext(ctx, span)
r, err := c.SayHello(ctx, &pb.HelloRequest{Name: "world"})
if err != nil {
log.Fatalf("could not greet: %v", err)
}
println("Response:", r.Message)
}
func clientInterceptor(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
// trace current request w/ child span
span := trace.FromContext(ctx).NewChild(method)
defer span.Finish()
// new metadata, or copy of existing
md, ok := metadata.FromContext(ctx)
if !ok {
md = metadata.New(nil)
} else {
md = md.Copy()
}
// append trace header to context metadata
// header specification: https://cloud.google.com/trace/docs/faq
md["X-Cloud-Trace-Context"] = append(
md["X-Cloud-Trace-Context"], fmt.Sprintf("%s/%d;o=1", span.TraceID(), 0),
)
ctx = metadata.NewContext(ctx, md)
return invoker(ctx, method, req, reply, cc, opts...)
}
.. and my gRPC server:
// server is used to implement helloworld.GreeterServer.
type server struct{}
// SayHello implements helloworld.GreeterServer
func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
println("HERE")
return &pb.HelloReply{Message: "Hello " + in.Name}, nil
}
func main() {
lis, err := net.Listen("tcp", ":50051")
if err != nil {
log.Fatalf("failed to listen: %v", err)
}
ctx := context.Background()
tc, err := trace.NewClient(ctx, "{PROJECT-ID}")
if err != nil {
log.Fatal(err)
}
s := grpc.NewServer(EnableGRPCTracingServerOption(tc))
pb.RegisterGreeterServer(s, &server{})
println("listening on :50051")
if err := s.Serve(lis); err != nil {
log.Fatalf("failed to serve: %v", err)
}
}
// EnableGRPCTracingServerOption enables parsing google trace header from metadata
// and adds a new child span to the incoming request context.
func EnableGRPCTracingServerOption(traceClient *trace.Client) grpc.ServerOption {
return grpc.UnaryInterceptor(serverInterceptor(traceClient))
}
func serverInterceptor(traceClient *trace.Client) grpc.UnaryServerInterceptor {
return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (resp interface{}, err error) {
// fetch metadata from request context
md, ok := metadata.FromContext(ctx)
if !ok {
md = metadata.New(nil)
}
header := strings.Join(md["X-Cloud-Trace-Context"], "")
// create new child span from google trace header, add to
// current request context
span := traceClient.SpanFromHeader(info.FullMethod, header)
defer span.Finish()
ctx = trace.NewContext(ctx, span)
return handler(ctx, req)
}
}
I when I run the client to initiate the trace, I get the error:
rpc error: code = 13 desc = stream terminated by RST_STREAM with error code: 1
I'm confused because I don't see anything else about authentication; only providing the project ID which can't be enough to initiate tracing for a specific project. What am I missing?
The issue was with:
defer span.Finish()
That call does not block so because I was just doing preliminary testing with one call my program was exiting before the traces could be uploaded. I contacted the author of https://rakyll.org/grpc-trace/ and she actually updated her post with the option of using:
defer span.FinishWait()
which blocks and that fixed it by allowing the traces to be successfully uploaded before the program exited.
Also, with a long running webserver this wouldn't have been an issue because the process wouldn't have been terminated.
I followed those same tutorials and ran into similar problems.
Header keys are converted to lowercase. If you retrieve it on the server side with header := strings.Join(md["x-cloud-trace-context"], "") you should be good.
You can also define your metadata headers with:
span := trace.FromContext(ctx).NewChild(method)
defer span.Finish()
md := metadata.Pairs(
"x-cloud-trace-context", fmt.Sprintf("%s/%d;o=1", span.TraceID(), 0),
)
ctx = metadata.NewContext(ctx, md)