From 74fe073e9acce820ff3815b78e49aadd10439d59 Mon Sep 17 00:00:00 2001
From: Doug Fawley <dfawley@google.com>
Date: Thu, 17 Jun 2021 16:53:52 -0700
Subject: [PATCH] Revert "xds: require router filter when filters are empty"
 (#4556)

This reverts commit 00ae0c57cc0a418f5208906d4f68c4b682dc662c.
---
 xds/internal/resolver/serviceconfig.go     | 3 +++
 xds/internal/resolver/xds_resolver_test.go | 5 -----
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/xds/internal/resolver/serviceconfig.go b/xds/internal/resolver/serviceconfig.go
index bf1c53fc93b..9eaff52dbcc 100644
--- a/xds/internal/resolver/serviceconfig.go
+++ b/xds/internal/resolver/serviceconfig.go
@@ -255,6 +255,9 @@ func (cs *configSelector) generateHash(rpcInfo iresolver.RPCInfo, hashPolicies [
 }
 
 func (cs *configSelector) newInterceptor(rt *route, cluster *routeCluster) (iresolver.ClientInterceptor, error) {
+	if len(cs.httpFilterConfig) == 0 {
+		return nil, nil
+	}
 	interceptors := make([]iresolver.ClientInterceptor, 0, len(cs.httpFilterConfig))
 	for _, filter := range cs.httpFilterConfig {
 		if router.IsRouterFilter(filter.Filter) {
diff --git a/xds/internal/resolver/xds_resolver_test.go b/xds/internal/resolver/xds_resolver_test.go
index 46229823580..9bce8ffe8bf 100644
--- a/xds/internal/resolver/xds_resolver_test.go
+++ b/xds/internal/resolver/xds_resolver_test.go
@@ -1197,11 +1197,6 @@ func (s) TestXDSResolverHTTPFilters(t *testing.T) {
 		selectErr    string
 		newStreamErr string
 	}{
-		{
-			name:       "empty filters",
-			ldsFilters: []xdsclient.HTTPFilter{},
-			selectErr:  "no router filter present",
-		},
 		{
 			name: "no router filter",
 			ldsFilters: []xdsclient.HTTPFilter{