Improve system behavior on low memory situation (#3781)

* Improve system behavior on low memory situation

Adjust OOM killer score to prevent crucial services from getting
selected.

* Adjust OOM score of DNS plug-in as well

supervisor/docker/addon.py

@@ -489,6 +489,7 @@ class DockerAddon(DockerInterface):
                 environment=self.environment,
                 volumes=self.volumes,
                 tmpfs=self.tmpfs,
+                oom_score_adj=200,
             )
         except DockerNotFound:
             self.sys_resolution.create_issue(

supervisor/docker/dns.py

@@ -50,6 +50,7 @@ class DockerDNS(DockerInterface, CoreSysAttributes):
                 str(self.sys_config.path_extern_dns): {"bind": "/config", "mode": "rw"},
                 DBUS_PATH: DBUS_VOLUME,
             },
+            oom_score_adj=-300,
         )
 
         self._meta = docker_container.attrs

supervisor/docker/homeassistant.py

@@ -149,6 +149,7 @@ class DockerHomeAssistant(DockerInterface):
                 ENV_TOKEN_OLD: self.sys_homeassistant.supervisor_token,
             },
             tmpfs={"/tmp": ""},
+            oom_score_adj=-300,
         )
 
         self._meta = docker_container.attrs

supervisor/docker/observer.py

@@ -55,6 +55,7 @@ class DockerObserver(DockerInterface, CoreSysAttributes):
             },
             volumes={"/run/docker.sock": {"bind": "/run/docker.sock", "mode": "ro"}},
             ports={"80/tcp": 4357},
+            oom_score_adj=-300,
         )
 
         self._meta = docker_container.attrs