use roundrobin for load balancing purposes

server.go

@@ -8,6 +8,7 @@ import (
 	"github.com/mholt/caddy/caddyhttp/httpserver"
 	"github.com/pieterlouw/caddy-grpc/proxy"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/balancer/roundrobin"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/metadata"
 
@@ -25,8 +26,10 @@ type server struct {
 // ServeHTTP satisfies the httpserver.Handler interface.
 func (s server) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
 	//dial Backend
-	opt := []grpc.DialOption{}
-	opt = append(opt, grpc.WithCodec(proxy.Codec()))
+	opt := []grpc.DialOption{
+		grpc.WithBalancerName(roundrobin.Name),
+		grpc.WithCodec(proxy.Codec()),
+	}
 	if s.backendIsInsecure {
 		opt = append(opt, grpc.WithInsecure())
 	} else {