Fix compatibility with latest grpc library

options.go

@@ -18,7 +18,7 @@ import (
 )
 
 type options struct {
-	creds                credentials.Credentials
+	creds                credentials.TransportCredentials
 	logger               grpclog.Logger
 	maxConcurrentStreams uint32
 }
@@ -43,7 +43,7 @@ func MaxConcurrentStreams(n uint32) ProxyOption {
 }
 
 // Creds returns a ProxyOption that sets credentials for server connections.
-func Creds(c credentials.Credentials) ProxyOption {
+func Creds(c credentials.TransportCredentials) ProxyOption {
 	return func(o *options) {
 		o.creds = c
 	}

patch/get_transport.go

@@ -0,0 +1,11 @@
+package grpc
+
+import (
+	"golang.org/x/net/context"
+	"google.golang.org/grpc/transport"
+)
+
+// GetTransport returns the balancer of the connection.
+func (cc *ClientConn) GetTransport(ctx context.Context) (transport.ClientTransport, func(), error) {
+	return cc.getTransport(ctx, BalancerGetOptions{})
+}

proxy.go

@@ -84,7 +84,7 @@ func (s *Proxy) Serve(lis net.Listener) error {
 			return err
 		}
 		var authInfo credentials.AuthInfo = nil
-		if creds, ok := s.opts.creds.(credentials.TransportAuthenticator); ok {
+		if creds, ok := s.opts.creds.(credentials.TransportCredentials); ok {
 			var conn net.Conn
 			conn, authInfo, err = creds.ServerHandshake(c)
 			if err != nil {
@@ -206,8 +206,9 @@ func backendTransportStream(director StreamDirector, ctx context.Context) (trans
 			return nil, nil, grpc.Errorf(codes.Aborted, "cant dial to backend: %v", err)
 		}
 	}
-	// TODO(michal): ClientConn.Picker() IS NOT IN UPSTREAM GRPC! https://github.com/grpc/grpc-go/pull/397
-	backendTrans, err := grpcConn.Picker().Pick(ctx)
+	// TODO(michal): ClientConn.GetTransport() IS NOT IN UPSTREAM GRPC!
+  // To make this work, copy patch/get_transport.go to google.golang.org/grpc/
+	backendTrans, _, err := grpcConn.GetTransport(ctx)
 	frontendStream, _ := transport.StreamFromContext(ctx)
 	callHdr := &transport.CallHdr{
 		Method: frontendStream.Method(),