Avoid early DNS plug-in start (#5922)

* Avoid early DNS plug-in start

A connectivity check can potentially be triggered before the DNS
plug-in is loaded. Avoid calling restart on the DNS plug-in before
it got initially loaded. This prevents starting before attaching.
The attaching makes sure that the DNS plug-in container is recreated
before the DNS plug-in is initially started, which is e.g. needed
by a potentially hassio network configuration change (e.g. the
migration required to enable/disable IPv6 on the hassio network,
see #5879).

* Mock DNS plug-in running

supervisor/host/network.py

@@ -158,6 +158,7 @@ class NetworkManager(CoreSysAttributes):
             DBUS_ATTR_PRIMARY_CONNECTION in changed
             and changed[DBUS_ATTR_PRIMARY_CONNECTION]
             and changed[DBUS_ATTR_PRIMARY_CONNECTION] != DBUS_OBJECT_BASE
+            and await self.sys_plugins.dns.is_running()
         ):
             await self.sys_plugins.dns.restart()
 

supervisor/plugins/dns.py

@@ -211,7 +211,7 @@ class PluginDns(PluginBase):
         try:
             await self.instance.restart()
         except DockerError as err:
-            raise CoreDNSError("Can't start CoreDNS plugin", _LOGGER.error) from err
+            raise CoreDNSError("Can't restart CoreDNS plugin", _LOGGER.error) from err
 
     async def start(self) -> None:
         """Run CoreDNS."""

tests/host/test_connectivity.py

@@ -2,7 +2,7 @@
 
 # pylint: disable=protected-access
 import asyncio
-from unittest.mock import PropertyMock, patch
+from unittest.mock import AsyncMock, PropertyMock, patch
 
 import pytest
 
@@ -92,7 +92,12 @@ async def test_dns_restart_on_connection_change(
 ):
     """Test dns plugin is restarted when primary connection changes."""
     await coresys.host.network.load()
-    with patch.object(PluginDns, "restart") as restart:
+    with (
+        patch.object(PluginDns, "restart") as restart,
+        patch.object(
+            PluginDns, "is_running", new_callable=AsyncMock, return_value=True
+        ),
+    ):
         network_manager_service.emit_properties_changed({"PrimaryConnection": "/"})
         await network_manager_service.ping()
         restart.assert_not_called()