Use correct default value for AddressResolver for DQ (#7922)

Author: Krock21

ydb/library/yql/providers/dq/actors/yt/resource_manager.h

@@ -73,7 +73,7 @@ namespace NYql {
 
         bool ForceIPv4 = false;
 
-        NYT::NYson::TYsonString AddressResolverConfig;
+        std::optional<NYT::NYson::TYsonString> AddressResolverConfig;
 
         // Pinger
         TString DieOnFileAbsence; // see YQL-14099

ydb/library/yql/providers/dq/actors/yt/yt_resource_manager.cpp

@@ -656,7 +656,9 @@ namespace NYql {
                                                 .Item(NCommonJobVars::OPERATION_SIZE).Value(ToString(nodes.size()))
                                                 .Item(NCommonJobVars::UDFS_PATH).Value(fileCache)
                                                 .Item(NCommonJobVars::ACTOR_NODE_ID).Value(ToString(nodeId))
-                                                .Item(NCommonJobVars::ADDRESS_RESOLVER_CONFIG).Value(ToString(NYT::NYson::ConvertToYsonString(Options.AddressResolverConfig, NYT::NYson::EYsonFormat::Text)))
+                                                .DoIf(!!Options.AddressResolverConfig, [&](NYT::TFluentMap fluent) {
+                                                    fluent.Item(NCommonJobVars::ADDRESS_RESOLVER_CONFIG).Value(ToString(NYT::NYson::ConvertToYsonString(Options.AddressResolverConfig, NYT::NYson::EYsonFormat::Text)));
+                                                })
                                                 .DoIf(!!GetEnv("YQL_DETERMINISTIC_MODE"), [&](NYT::TFluentMap fluent) {
                                                     fluent.Item("YQL_DETERMINISTIC_MODE").Value("1");
                                                 })

ydb/library/yql/tools/dq/worker_job/dq_worker.cpp

@@ -172,7 +172,6 @@ namespace NYql::NDq::NWorker {
         TString fileCacheDir = GetEnv(NCommonJobVars::UDFS_PATH);
         TString ytCoordinatorStr = GetEnv(TString("YT_SECURE_VAULT_") + NCommonJobVars::YT_COORDINATOR);
         TString ytBackendStr = GetEnv(TString("YT_SECURE_VAULT_") + NCommonJobVars::YT_BACKEND);
-        NYT::NYson::TYsonString addressResolverYson = NYT::NYson::TYsonString(GetEnv(NCommonJobVars::ADDRESS_RESOLVER_CONFIG));
 
         TString operationId = GetEnv("YT_OPERATION_ID");
         TString jobId = GetEnv("YT_JOB_ID");
@@ -190,11 +189,20 @@ namespace NYql::NDq::NWorker {
         TRangeWalker<int> portWalker(startPort, startPort+100);
         auto ports = BindInRange(portWalker);
 
-        auto addressResolverConfig = NYT::NYTree::ConvertTo<NYT::NNet::TAddressResolverConfigPtr>(addressResolverYson);
-        NYT::NNet::TAddressResolver::Get()->Configure(addressResolverConfig);
-
         auto forceIPv4 = IsTrue(GetEnv(TString("YT_SECURE_VAULT_") + NCommonJobVars::YT_FORCE_IPV4, ""));
 
+        auto addressResolverStr = GetEnv(NCommonJobVars::ADDRESS_RESOLVER_CONFIG, "");
+        if (!addressResolverStr.Empty()) {
+            auto addressResolverConfig = NYT::NYTree::ConvertTo<NYT::NNet::TAddressResolverConfigPtr>(NYT::NYson::TYsonString(addressResolverStr));
+            NYT::NNet::TAddressResolver::Get()->Configure(addressResolverConfig);
+        } else if (forceIPv4) {
+            // Keep the previous behavior for compatibility.
+            auto config = NYT::New<NYT::NNet::TAddressResolverConfig>();
+            config->EnableIPv4 = true;
+            config->EnableIPv6 = false;
+            NYT::NNet::TAddressResolver::Get()->Configure(config);
+        }
+
         auto [host, ip] = NYql::NDqs::GetLocalAddress(
             coordinatorConfig.HasHostName() ? &coordinatorConfig.GetHostName() : nullptr,
             forceIPv4 ? AF_INET : AF_INET6