[feature] Added connection notification logic from openwisp-monitoring …

…#269

Moves code from openwisp-monitoring to openwisp-controller:
openwisp/openwisp-monitoring#226

Closes #269

openwisp_controller/connection/apps.py

@@ -3,9 +3,12 @@
 from django.db import transaction
 from django.db.models.signals import post_save
 from django.utils.translation import ugettext_lazy as _
+from openwisp_notifications.signals import notify
+from openwisp_notifications.types import register_notification_type
 from swapper import load_model
 
 from ..config.signals import config_modified
+from .signals import is_working_changed
 
 _TASK_NAME = 'openwisp_controller.connection.tasks.update_config'
 
@@ -21,6 +24,7 @@ def ready(self):
         to the ``update_config`` celery task
         which will be executed in the background
         """
+        self.register_notification_types()
         config_modified.connect(
             self.config_modified_receiver, dispatch_uid='connection.update_config'
         )
@@ -31,6 +35,11 @@ def ready(self):
             sender=Config,
             dispatch_uid='connection.auto_add_credentials',
         )
+        is_working_changed.connect(
+            self.is_working_changed_receiver,
+            sender=load_model('connection', 'DeviceConnection'),
+            dispatch_uid='is_working_changed_receiver',
+        )
 
     @classmethod
     def config_modified_receiver(cls, **kwargs):
@@ -64,3 +73,49 @@ def _is_update_in_progress(cls, device_pk):
                 if task['name'] == _TASK_NAME and str(device_pk) in task['args']:
                     return True
         return False
+
+    @classmethod
+    def is_working_changed_receiver(cls, instance, is_working, **kwargs):
+        device = instance.device
+        notification_opts = dict(sender=instance, target=device)
+        if not is_working:
+            notification_opts['type'] = 'connection_is_not_working'
+        else:
+            notification_opts['type'] = 'connection_is_working'
+        notify.send(**notification_opts)
+
+    def register_notification_types(self):
+        register_notification_type(
+            'connection_is_not_working',
+            {
+                'verbose_name': 'Device Connection PROBLEM',
+                'verb': 'not working',
+                'level': 'error',
+                'email_subject': (
+                    '[{site.name}] PROBLEM: Connection to '
+                    'device {notification.target}'
+                ),
+                'message': (
+                    '{notification.actor.credentials} connection to '
+                    'device [{notification.target}]({notification.target_link}) '
+                    'is {notification.verb}. {notification.actor.failure_reason}'
+                ),
+            },
+        )
+        register_notification_type(
+            'connection_is_working',
+            {
+                'verbose_name': 'Device Connection RECOVERY',
+                'verb': 'working',
+                'level': 'info',
+                'email_subject': (
+                    '[{site.name}] RECOVERY: Connection to '
+                    'device {notification.target}'
+                ),
+                'message': (
+                    '{notification.actor.credentials} connection to '
+                    'device [{notification.target}]({notification.target_link}) '
+                    'is {notification.verb}. {notification.actor.failure_reason}'
+                ),
+            },
+        )

openwisp_controller/connection/tests/test_notifications.py

@@ -0,0 +1,124 @@
+from django.apps.registry import apps
+from django.core import mail
+from django.urls import reverse
+from django.utils.html import strip_tags
+from openwisp_notifications.types import unregister_notification_type
+from swapper import load_model
+
+from .utils import CreateConnectionsMixin
+
+Notification = load_model('openwisp_notifications', 'Notification')
+Credentials = load_model('connection', 'Credentials')
+DeviceConnection = load_model('connection', 'DeviceConnection')
+
+
+class TestNotifications(CreateConnectionsMixin):
+    app_label = 'connection'
+
+    def setUp(self):
+        self._create_admin()
+        self.d = self._create_device()
+        self.creds = Credentials.objects.create(
+            connector='openwisp_controller.connection.connectors.ssh.Ssh'
+        )
+        self.dc = DeviceConnection.objects.create(credentials=self.creds, device=self.d)
+
+    def _generic_notification_test(
+        self, exp_level, exp_type, exp_verb, exp_message, exp_email_subject
+    ):
+        n = Notification.objects.first()
+        url_path = reverse('notifications:notification_read_redirect', args=[n.pk])
+        exp_email_link = f'https://example.com{url_path}'
+        exp_target_link = f'https://example.com/admin/config/device/{self.d.id}/change/'
+        exp_email_body = '{message}' f'\n\nFor more information see {exp_email_link}.'
+
+        email = mail.outbox.pop()
+        html_message, _ = email.alternatives.pop()
+        self.assertEqual(n.type, exp_type)
+        self.assertEqual(n.level, exp_level)
+        self.assertEqual(n.verb, exp_verb)
+        self.assertEqual(n.actor, self.dc)
+        self.assertEqual(n.target, self.d)
+        self.assertEqual(
+            n.message, exp_message.format(n=n, target_link=exp_target_link)
+        )
+        self.assertEqual(
+            n.email_subject, exp_email_subject.format(n=n),
+        )
+        self.assertEqual(email.subject, n.email_subject)
+        self.assertEqual(
+            email.body, exp_email_body.format(message=strip_tags(n.message))
+        )
+        self.assertIn(
+            f'<a href="{exp_email_link}">'
+            'For further information see "device: default.test.device".</a>',
+            html_message,
+        )
+
+    def test_connection_working_notification(self):
+        self.assertEqual(Notification.objects.count(), 0)
+        self.dc = DeviceConnection.objects.create(
+            credentials=self.creds, device=self.d, is_working=False
+        )
+        self.dc.is_working = True
+        self.dc.save()
+        self.assertEqual(Notification.objects.count(), 1)
+        self._generic_notification_test(
+            exp_level='info',
+            exp_type='connection_is_working',
+            exp_verb='working',
+            exp_message=(
+                '<p>(SSH) connection to device <a href="{target_link}">'
+                '{n.target}</a> is {n.verb}. </p>'
+            ),
+            exp_email_subject='[example.com] RECOVERY: Connection to device {n.target}',
+        )
+
+    def test_connection_not_working_notification(self):
+        self.assertEqual(Notification.objects.count(), 0)
+        self.dc.is_working = False
+        self.dc.save()
+        self.assertEqual(Notification.objects.count(), 1)
+        self._generic_notification_test(
+            exp_level='error',
+            exp_type='connection_is_not_working',
+            exp_verb='not working',
+            exp_message=(
+                '<p>(SSH) connection to device <a href="{target_link}">'
+                '{n.target}</a> is {n.verb}. </p>'
+            ),
+            exp_email_subject='[example.com] PROBLEM: Connection to device {n.target}',
+        )
+
+    def test_unreachable_after_upgrade_notification(self):
+        self.assertEqual(Notification.objects.count(), 0)
+        self.dc.is_working = False
+        self.dc.failure_reason = 'Giving up, device not reachable anymore after upgrade'
+        self.dc.save()
+        self.assertEqual(Notification.objects.count(), 1)
+        self._generic_notification_test(
+            exp_level='error',
+            exp_type='connection_is_not_working',
+            exp_verb='not working',
+            exp_message=(
+                '<p>(SSH) connection to device <a href="{target_link}">'
+                '{n.target}</a> is {n.verb}. '
+                'Giving up, device not reachable anymore after upgrade</p>'
+            ),
+            exp_email_subject='[example.com] PROBLEM: Connection to device {n.target}',
+        )
+
+    def test_default_notification_type_already_unregistered(self):
+        # Simulates if 'default notification type is already unregistered
+        # by some other module
+
+        # Unregister "config_error" and "device_registered" notification
+        # types to avoid getting rasing ImproperlyConfigured exceptions
+        unregister_notification_type('connection_is_not_working')
+        unregister_notification_type('connection_is_working')
+
+        # This will try to unregister 'default' notification type
+        # which is already got unregistered when Django loaded.
+        # No exception should be raised as the exception is already handled.
+        app = apps.get_app_config(self.app_label)
+        app.register_notification_types()

tests/openwisp2/sample_connection/tests.py

@@ -5,6 +5,9 @@
 from openwisp_controller.connection.tests.test_models import (
     TestModelsTransaction as BaseTestModelsTransaction,
 )
+from openwisp_controller.connection.tests.test_notifications import (
+    TestNotifications as BaseTestNotifications,
+)
 from openwisp_controller.connection.tests.test_ssh import TestSsh as BaseTestSsh
 
 
@@ -25,7 +28,12 @@ class TestSsh(BaseTestSsh):
     pass
 
 
+class TestNotifications(BaseTestNotifications):
+    app_label = 'sample_connection'
+
+
 del BaseTestAdmin
 del BaseTestModels
 del BaseTestModelsTransaction
 del BaseTestSsh
+del BaseTestNotifications