Use github.com/sercand/kuberesolver for grpc forwarding in kubernetes

Author: singron

cmd/veneur/main.go

@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/getsentry/raven-go"
+	"github.com/sercand/kuberesolver"
 	"github.com/sirupsen/logrus"
 	"github.com/stripe/veneur"
 	"github.com/stripe/veneur/ssf"
@@ -47,6 +48,10 @@ func main() {
 	}
 
 	logger := logrus.StandardLogger()
+	// This is safe outside of a cluster althouth attempting to use a
+	// kubernetes:// url will cause a failure.
+	kuberesolver.RegisterInCluster()
+
 	server, err := veneur.NewFromConfig(logger, conf)
 	veneur.SetLogger(logger)
 	if err != nil {

example.yaml

@@ -40,6 +40,10 @@ tls_authority_certificate: ""
 # Use a static host for forwarding
 #forward_address: "http://veneur.example.com"
 # Do not add a prefix when setting the forward address for gRPC.
+# If using grpc in a kubernetes cluster, you may use urls compatible with
+# https://github.com/sercand/kuberesolver to get better native load balancing
+# behavior than the connection-based load balancing provided by kubernetes
+# services.
 #forward_address: "veneur.example.com"
 forward_address: ""
 

server.go

@@ -32,6 +32,7 @@ import (
 	"github.com/zenazn/goji/bind"
 	"github.com/zenazn/goji/graceful"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/balancer/roundrobin"
 
 	"github.com/pkg/profile"
 
@@ -842,7 +843,8 @@ func (s *Server) Start() {
 	// Initialize a gRPC connection for forwarding
 	if s.forwardUseGRPC {
 		var err error
-		s.grpcForwardConn, err = grpc.Dial(s.ForwardAddr, grpc.WithInsecure())
+		s.grpcForwardConn, err = grpc.Dial(s.ForwardAddr, grpc.WithInsecure(),
+			grpc.WithBalancerName(roundrobin.Name))
 		if err != nil {
 			log.WithError(err).WithFields(logrus.Fields{
 				"forwardAddr": s.ForwardAddr,