Merge pull request #10034 from gyuho/init-metrics-3.1

etcdserver/api/v3rpc: display all registered gRPC metrics at start (v3.1)

etcdserver/api/v3rpc/grpc.go

@@ -19,6 +19,8 @@ import (
 
 	"github.com/coreos/etcd/etcdserver"
 	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+
+	"github.com/grpc-ecosystem/go-grpc-prometheus"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/grpclog"
@@ -45,5 +47,8 @@ func Server(s *etcdserver.EtcdServer, tls *tls.Config) *grpc.Server {
 	pb.RegisterAuthServer(grpcServer, NewAuthServer(s))
 	pb.RegisterMaintenanceServer(grpcServer, NewMaintenanceServer(s))
 
+	// to display all registered metrics with zero values
+	grpc_prometheus.Register(grpcServer)
+
 	return grpcServer
 }