better resolv.conf, add DNSCacheUpdater logs

programs/server/Server.cpp

@@ -716,6 +716,7 @@ int Server::main(const std::vector<std::string> & /*args*/)
     {
         /// Disable DNS caching at all
         DNSResolver::instance().setDisableCacheFlag();
+        LOG_DEBUG(log, "DNS caching disabled");
     }
     else
     {

src/Interpreters/DNSCacheUpdater.cpp

@@ -42,6 +42,7 @@ void DNSCacheUpdater::run()
 
 void DNSCacheUpdater::start()
 {
+    LOG_INFO(&Poco::Logger::get("DNSCacheUpdater"), "Update period {} seconds", update_period_seconds);
     task_handle->activateAndSchedule();
 }
 

tests/integration/helpers/cluster.py

@@ -727,6 +727,11 @@ services:
             - {env_file}
         security_opt:
             - label:disable
+        dns_opt:
+            - attempts:2
+            - timeout:1
+            - inet6
+            - rotate
         {networks}
             {app_net}
                 {ipv4_address}
@@ -740,8 +745,8 @@ class ClickHouseInstance:
 
     def __init__(
             self, cluster, base_path, name, custom_config_dir, custom_main_configs, custom_user_configs, macros,
-            with_zookeeper, zookeeper_config_path, with_mysql, with_kafka, with_rabbitmq, with_mongo, with_redis, with_minio, with_cassandra,
-            base_configs_dir, server_bin_path, odbc_bridge_bin_path,
+            with_zookeeper, zookeeper_config_path, with_mysql, with_kafka, with_rabbitmq, with_mongo,
+            with_redis, with_minio, with_cassandra, base_configs_dir, server_bin_path, odbc_bridge_bin_path,
             clickhouse_path_dir, with_odbc_drivers, hostname=None, env_variables=None,
             image="yandex/clickhouse-integration-test", tag="latest",
             stay_alive=False, ipv4_address=None, ipv6_address=None, with_installed_binary=False, tmpfs=None):

tests/integration/test_host_ip_change/test.py

@@ -111,8 +111,13 @@ def test_ip_change_update_dns_cache(cluster_with_dns_cache_update):
     # Check that data is placed on node3
     assert node3.query("SELECT count(*) from test_table_update") == "6\n"
 
-    result = node4.exec_in_container(["bash", "-c", "/usr/bin/host node3"])
-    print("HOST RESULT %s", result)
+    curl_result = node4.exec_in_container(["bash", "-c", "curl -s 'node3:8123'"])
+    assert curl_result == 'Ok.\n'
+    cat_resolv = node4.exec_in_container(["bash", "-c", "cat /etc/resolv.conf"])
+    print("RESOLV {}".format(cat_resolv))
+
+
+    assert node4.query("SELECT * FROM remote('node3', 'system', 'one')") == "0\n"
 
     # Because of DNS cache update, ip of node3 would be updated
     assert_eq_with_retry(node4, "SELECT count(*) from test_table_update", "6", sleep_time=3)