xDS: improve status messages from xDS resolver failures (#29975)

src/core/ext/filters/client_channel/resolver/xds/xds_resolver.cc

@@ -187,7 +187,9 @@ class XdsResolver : public Resolver {
       Ref().release();  // ref held by lambda
       resolver_->work_serializer_->Run(
           [this]() {
-            resolver_->OnResourceDoesNotExist();
+            resolver_->OnResourceDoesNotExist(
+                absl::StrCat(resolver_->lds_resource_name_,
+                             ": xDS listener resource does not exist"));
             Unref();
           },
           DEBUG_LOCATION);
@@ -226,7 +228,9 @@ class XdsResolver : public Resolver {
       Ref().release();  // ref held by lambda
       resolver_->work_serializer_->Run(
           [this]() {
-            resolver_->OnResourceDoesNotExist();
+            resolver_->OnResourceDoesNotExist(absl::StrCat(
+                resolver_->route_config_name_,
+                ": xDS route configuration resource does not exist"));
             Unref();
           },
           DEBUG_LOCATION);
@@ -357,7 +361,7 @@ class XdsResolver : public Resolver {
   void OnListenerUpdate(XdsListenerResource listener);
   void OnRouteConfigUpdate(XdsRouteConfigResource rds_update);
   void OnError(absl::string_view context, absl::Status status);
-  void OnResourceDoesNotExist();
+  void OnResourceDoesNotExist(std::string context);
 
   absl::StatusOr<RefCountedPtr<ServiceConfig>> CreateServiceConfig();
   void GenerateResult();
@@ -977,7 +981,7 @@ void XdsResolver::OnError(absl::string_view context, absl::Status status) {
   result_handler_->ReportResult(std::move(result));
 }
 
-void XdsResolver::OnResourceDoesNotExist() {
+void XdsResolver::OnResourceDoesNotExist(std::string context) {
   gpr_log(GPR_ERROR,
           "[xds_resolver %p] LDS/RDS resource does not exist -- clearing "
           "update and returning empty service config",
@@ -991,6 +995,7 @@ void XdsResolver::OnResourceDoesNotExist() {
   grpc_error_handle error = GRPC_ERROR_NONE;
   result.service_config = ServiceConfigImpl::Create(args_, "{}", &error);
   GPR_ASSERT(*result.service_config != nullptr);
+  result.resolution_note = std::move(context);
   result.args = grpc_channel_args_copy(args_);
   result_handler_->ReportResult(std::move(result));
 }

test/cpp/end2end/xds/xds_core_end2end_test.cc

@@ -395,20 +395,18 @@ INSTANTIATE_TEST_SUITE_P(
 
 TEST_P(TimeoutTest, LdsServerIgnoresRequest) {
   balancer_->ads_service()->IgnoreResourceType(kLdsTypeUrl);
-  CheckRpcSendFailure(
-      DEBUG_LOCATION, StatusCode::UNAVAILABLE,
-      // TODO(roth): Improve this error as part of
-      // https://github.com/grpc/grpc/issues/22883.
-      "empty address list: ", RpcOptions().set_timeout_ms(4000));
+  CheckRpcSendFailure(DEBUG_LOCATION, StatusCode::UNAVAILABLE,
+                      absl::StrCat("empty address list: ", kServerName,
+                                   ": xDS listener resource does not exist"),
+                      RpcOptions().set_timeout_ms(4000));
 }
 
 TEST_P(TimeoutTest, LdsResourceNotPresentInRequest) {
   balancer_->ads_service()->UnsetResource(kLdsTypeUrl, kServerName);
-  CheckRpcSendFailure(
-      DEBUG_LOCATION, StatusCode::UNAVAILABLE,
-      // TODO(roth): Improve this error as part of
-      // https://github.com/grpc/grpc/issues/22883.
-      "empty address list: ", RpcOptions().set_timeout_ms(4000));
+  CheckRpcSendFailure(DEBUG_LOCATION, StatusCode::UNAVAILABLE,
+                      absl::StrCat("empty address list: ", kServerName,
+                                   ": xDS listener resource does not exist"),
+                      RpcOptions().set_timeout_ms(4000));
 }
 
 TEST_P(TimeoutTest, LdsSecondResourceNotPresentInRequest) {
@@ -434,18 +432,17 @@ TEST_P(TimeoutTest, LdsSecondResourceNotPresentInRequest) {
       SendRpcMethod(stub2.get(), rpc_options, &context, request, &response);
   EXPECT_EQ(StatusCode::UNAVAILABLE, status.error_code());
   EXPECT_THAT(status.error_message(),
-              // TODO(roth): Improve this error as part of
-              // https://github.com/grpc/grpc/issues/22883.
-              "empty address list: ");
+              absl::StrCat("empty address list: ", kNewServerName,
+                           ": xDS listener resource does not exist"));
 }
 
 TEST_P(TimeoutTest, RdsServerIgnoresRequest) {
   balancer_->ads_service()->IgnoreResourceType(kRdsTypeUrl);
   CheckRpcSendFailure(
       DEBUG_LOCATION, StatusCode::UNAVAILABLE,
-      // TODO(roth): Improve this error as part of
-      // https://github.com/grpc/grpc/issues/22883.
-      "empty address list: ", RpcOptions().set_timeout_ms(4000));
+      absl::StrCat("empty address list: ", kDefaultRouteConfigurationName,
+                   ": xDS route configuration resource does not exist"),
+      RpcOptions().set_timeout_ms(4000));
 }
 
 TEST_P(TimeoutTest, RdsResourceNotPresentInRequest) {
@@ -453,9 +450,9 @@ TEST_P(TimeoutTest, RdsResourceNotPresentInRequest) {
                                           kDefaultRouteConfigurationName);
   CheckRpcSendFailure(
       DEBUG_LOCATION, StatusCode::UNAVAILABLE,
-      // TODO(roth): Improve this error as part of
-      // https://github.com/grpc/grpc/issues/22883.
-      "empty address list: ", RpcOptions().set_timeout_ms(4000));
+      absl::StrCat("empty address list: ", kDefaultRouteConfigurationName,
+                   ": xDS route configuration resource does not exist"),
+      RpcOptions().set_timeout_ms(4000));
 }
 
 TEST_P(TimeoutTest, RdsSecondResourceNotPresentInRequest) {
@@ -492,10 +489,10 @@ TEST_P(TimeoutTest, RdsSecondResourceNotPresentInRequest) {
   auto status =
       SendRpcMethod(stub2.get(), rpc_options, &context, request, &response);
   EXPECT_EQ(StatusCode::UNAVAILABLE, status.error_code());
-  EXPECT_EQ(status.error_message(),
-            // TODO(roth): Improve this error as part of
-            // https://github.com/grpc/grpc/issues/22883.
-            "empty address list: ");
+  EXPECT_THAT(
+      status.error_message(),
+      absl::StrCat("empty address list: ", kNewRouteConfigName,
+                   ": xDS route configuration resource does not exist"));
 }
 
 TEST_P(TimeoutTest, CdsServerIgnoresRequest) {

test/cpp/end2end/xds/xds_csds_end2end_test.cc

@@ -634,11 +634,10 @@ INSTANTIATE_TEST_SUITE_P(
 TEST_P(CsdsShortAdsTimeoutTest, XdsConfigDumpListenerDoesNotExist) {
   int kTimeoutMillisecond = 1000000;  // 1000s wait for the transient failure.
   balancer_->ads_service()->UnsetResource(kLdsTypeUrl, kServerName);
-  CheckRpcSendFailure(
-      DEBUG_LOCATION, StatusCode::UNAVAILABLE,
-      // TODO(roth): Improve this error as part of
-      // https://github.com/grpc/grpc/issues/22883.
-      "empty address list: ", RpcOptions().set_timeout_ms(kTimeoutMillisecond));
+  CheckRpcSendFailure(DEBUG_LOCATION, StatusCode::UNAVAILABLE,
+                      absl::StrCat("empty address list: ", kServerName,
+                                   ": xDS listener resource does not exist"),
+                      RpcOptions().set_timeout_ms(kTimeoutMillisecond));
   auto csds_response = FetchCsdsResponse();
   EXPECT_THAT(csds_response.config(0).generic_xds_configs(),
               ::testing::Contains(EqGenericXdsConfig(
@@ -653,9 +652,9 @@ TEST_P(CsdsShortAdsTimeoutTest, XdsConfigDumpRouteConfigDoesNotExist) {
                                           kDefaultRouteConfigurationName);
   CheckRpcSendFailure(
       DEBUG_LOCATION, StatusCode::UNAVAILABLE,
-      // TODO(roth): Improve this error as part of
-      // https://github.com/grpc/grpc/issues/22883.
-      "empty address list: ", RpcOptions().set_timeout_ms(kTimeoutMillisecond));
+      absl::StrCat("empty address list: ", kDefaultRouteConfigurationName,
+                   ": xDS route configuration resource does not exist"),
+      RpcOptions().set_timeout_ms(kTimeoutMillisecond));
   auto csds_response = FetchCsdsResponse();
   EXPECT_THAT(
       csds_response.config(0).generic_xds_configs(),

test/cpp/end2end/xds/xds_routing_end2end_test.cc

@@ -478,9 +478,8 @@ TEST_P(LdsDeletionTest, ListenerDeleted) {
     if (result.status.ok()) return true;  // Keep going.
     EXPECT_EQ(result.status.error_code(), StatusCode::UNAVAILABLE);
     EXPECT_EQ(result.status.error_message(),
-              // TODO(roth): Improve this error message as part of
-              // https://github.com/grpc/grpc/issues/22883.
-              "empty address list: ");
+              absl::StrCat("empty address list: ", kServerName,
+                           ": xDS listener resource does not exist"));
     return false;
   });
   // Make sure we ACK'ed the update.