feat(request_forwarder): Add config option to set DNS cache TTL

coco/core.py

@@ -85,10 +85,17 @@ def __init__(self, conf, reset=False, check_config=False):
             raise ConfigError(
                 f"Failed parsing value 'timeout' ({self.config['timeout']})."
             ) from e
+        try:
+            dns_cache_ttl = str2total_seconds(self.config["dns_cache_ttl"])
+        except Exception as e:
+            raise ConfigError(
+                f"Failed parsing value 'dns_cache_ttl' ({self.config['dns_cache_ttl']})."
+            ) from e
         self.forwarder = RequestForwarder(
             self.blocklist_path,
             timeout,
             debug_connections=self.config["debug_connections"],
+            dns_cache_ttl=dns_cache_ttl
         )
         self.forwarder.set_session_limit(self.config["session_limit"])
         for group, hosts in self.groups.items():

coco/request_forwarder.py

@@ -196,7 +196,7 @@ class RequestForwarder:
     """
 
     def __init__(
-        self, blocklist_path: os.PathLike, timeout: int, debug_connections: bool = False
+        self, blocklist_path: os.PathLike, timeout: int, debug_connections: bool = False, dns_cache_ttl: int = 10
     ):
         self._endpoints = dict()
         self._groups = dict()
@@ -210,6 +210,7 @@ def __init__(
         self.queue_wait_time = None
         self.response_time = None
         self._debug_connections = debug_connections
+        self._connector = aiohttp.TCPConnector(limit=0, ttl_dns_cache=dns_cache_ttl)
 
     def set_session_limit(self, session_limit):
         """
@@ -421,9 +422,8 @@ async def external(self, name, request, hosts, method, params=None, timeout=None
         if timeout is None:
             timeout = self.timeout
 
-        connector = aiohttp.TCPConnector(limit=0)
         async with aiohttp.ClientSession(
-            connector=connector,
+            connector=self._connector,
             trace_configs=([_trace_config()] if self._debug_connections else None),
         ) as session, TaskPool(self.session_limit) as tasks:
             for host in hosts:

coco/test/coco_runner.py

@@ -18,6 +18,7 @@
     "host": "localhost",
     "port": 12055,
     "log_level": "DEBUG",
+    "dns_cache_ttl": 60,
     "blocklist_path": str(BLOCKLIST_PATH),
     "storage_path": STATE_DIR.name,
 }