Support some c-ares options in YT config

No description

---
3971a04217d89905831824822771973f898d4f40

Pull Request resolved: https://github.com/ytsaurus/ytsaurus/pull/500

3 files changed, 21 insertions, 1 deletions

diff --git a/yt/yt/core/dns/ares_dns_resolver.cpp b/yt/yt/core/dns/ares_dns_resolver.cpp
index 44eee4eb9c..799a681c3c 100644
--- a/yt/yt/core/dns/ares_dns_resolver.cpp
+++ b/yt/yt/core/dns/ares_dns_resolver.cpp
@@ -146,8 +146,15 @@ public:
 
         // See https://c-ares.haxx.se/ares_init_options.html for full details.
         int mask = 0;
-        Options_.flags |= ARES_FLAG_STAYOPEN;
+
+        if (Config_->ForceTcp) {
+            Options_.flags |= ARES_FLAG_USEVC;
+        }
+        if (Config_->KeepSocket) {
+            Options_.flags |= ARES_FLAG_STAYOPEN;
+        }
         mask |= ARES_OPT_FLAGS;
+
         Options_.timeout = static_cast<int>(Config_->ResolveTimeout.MilliSeconds());
         mask |= ARES_OPT_TIMEOUTMS;
 
diff --git a/yt/yt/core/dns/config.cpp b/yt/yt/core/dns/config.cpp
index 302cb67eb1..1765d7cb8d 100644
--- a/yt/yt/core/dns/config.cpp
+++ b/yt/yt/core/dns/config.cpp
@@ -18,6 +18,10 @@ void TAresDnsResolverConfig::Register(TRegistrar registrar)
         .Default(TDuration::Seconds(3));
     registrar.Parameter("jitter", &TThis::Jitter)
         .Default(0.5);
+    registrar.Parameter("force_tcp", &TThis::ForceTcp)
+        .Default(false);
+    registrar.Parameter("keep_socket", &TThis::KeepSocket)
+        .Default(true);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/yt/yt/core/dns/config.h b/yt/yt/core/dns/config.h
index b6d7c6e5cc..7e68a0fbc8 100644
--- a/yt/yt/core/dns/config.h
+++ b/yt/yt/core/dns/config.h
@@ -14,6 +14,7 @@ class TAresDnsResolverConfig
 public:
     bool EnableIPv4;
     bool EnableIPv6;
+
     //! If true, when determining local host name, it will additionally be resolved
     //! into FQDN by calling |getaddrinfo|. Setting this option to false may be
     //! useful in MTN environment, in which hostnames are barely resolvable.
@@ -33,6 +34,14 @@ public:
     //! Used to check that bootstrap is being initialized from a correct container.
     std::optional<TString> ExpectedLocalHostName;
 
+    //! If set, Ares forcefully uses TCP for DNS queries.
+    //! See ARES_FLAG_USEVC.
+    bool ForceTcp;
+
+    //! If set, Ares keeps socket open even if there are no active queries.
+    //! See ARES_FLAG_STAYOPEN.
+    bool KeepSocket;
+
     REGISTER_YSON_STRUCT(TAresDnsResolverConfig);
 
     static void Register(TRegistrar registrar);