[change] Timeseries data is deleted when device is deleted #419

Closes #419

openwisp_monitoring/device/tests/test_models.py

@@ -649,6 +649,29 @@ def test_unknown_critical(self):
         dm.refresh_from_db()
         self.assertEqual(dm.status, 'critical')
 
+    def test_deleting_device_deletes_tsdb(self):
+        dm1, ping1, _, _ = self._create_env()
+        device2 = self._create_device(
+            name='default.test.device2',
+            mac_address='22:33:44:55:66:77',
+            organization=dm1.device.organization,
+        )
+        dm2 = device2.monitoring
+        dm2.status = 'ok'
+        dm2.save()
+        ping2 = self._create_object_metric(
+            name='ping', key='ping', field_name='reachable', content_object=device2
+        )
+        ping1.write(0)
+        ping2.write(0)
+        self.assertNotEqual(ping1.read(), [])
+        self.assertNotEqual(ping2.read(), [])
+        dm1.device.delete()
+        # Only the metric related to the deleted device
+        # is deleted
+        self.assertEqual(ping1.read(), [])
+        self.assertNotEqual(ping2.read(), [])
+
 
 class TestWifiClientSession(TestWifiClientSessionMixin, TestCase):
     wifi_client_model = WifiClient

openwisp_monitoring/monitoring/apps.py

@@ -1,7 +1,8 @@
 from django.apps import AppConfig
 from django.conf import settings
+from django.db.models.signals import post_delete
 from django.utils.translation import gettext_lazy as _
-from swapper import get_model_name
+from swapper import get_model_name, load_model
 
 from openwisp_utils.admin_theme.menu import register_menu_group
 
@@ -21,6 +22,7 @@ def ready(self):
         for metric_name, metric_config in metrics.items():
             register_metric_notifications(metric_name, metric_config)
         self.register_menu_groups()
+        self.connect_metric_signals()
 
     def register_menu_groups(self):
         register_menu_group(
@@ -44,3 +46,11 @@ def register_menu_groups(self):
                 'icon': 'ow-monitoring',
             },
         )
+
+    def connect_metric_signals(self):
+        Metric = load_model('monitoring', 'Metric')
+        post_delete.connect(
+            Metric.post_delete_receiver,
+            sender=Metric,
+            dispatch_uid='metric_post_delete_receiver',
+        )

openwisp_monitoring/monitoring/base/models.py

@@ -33,7 +33,7 @@
 )
 from ..exceptions import InvalidChartConfigException, InvalidMetricConfigException
 from ..signals import pre_metric_write, threshold_crossed
-from ..tasks import timeseries_write
+from ..tasks import delete_timeseries, timeseries_write
 
 User = get_user_model()
 logger = logging.getLogger(__name__)
@@ -115,6 +115,10 @@ def full_clean(self, *args, **kwargs):
         self.key = self._makekey(self.key)
         return super().full_clean(*args, **kwargs)
 
+    @classmethod
+    def post_delete_receiver(cls, instance, *args, **kwargs):
+        delete_timeseries.delay(instance.key, instance.tags)
+
     @classmethod
     def _get_or_create(cls, **kwargs):
         """

openwisp_monitoring/monitoring/tasks.py

@@ -36,6 +36,11 @@ def timeseries_write(
         post_metric_write.send(**signal_kwargs)
 
 
+@shared_task
+def delete_timeseries(key, tags):
+    timeseries_db.delete_series(key=key, tags=tags)
+
+
 @shared_task
 def migrate_timeseries_database():
     """

openwisp_monitoring/monitoring/tests/test_models.py

@@ -349,3 +349,16 @@ def test_get_time_str(self):
         m = self._create_general_metric(name='load')
         now = timezone.now()
         self.assertEqual(m._get_time(now.isoformat()), now)
+
+    def test_deleting_metric_deletes_timeseries(self):
+        metric1 = self._create_general_metric(name='load')
+        metric2 = self._create_general_metric(name='traffic')
+        metric1.write(99)
+        metric2.write(5000)
+        self.assertNotEqual(metric1.read(), [])
+        self.assertNotEqual(metric2.read(), [])
+        metric1.delete()
+        self.assertEqual(metric1.read(), [])
+        # Only the timeseries data related to the deleted metric
+        # should be deleted
+        self.assertNotEqual(metric2.read(), [])