Maintenance Mode Update (#6462)

* Adjust maintenance mode backend

- Save a timestamp to the setting, after which maintenance mode is not active
- Fallback to account for possibility that race condition / exception leaves maintenance mode active

* Update docstring

* Remove unused import

* Add unit tests for maintenance mode

InvenTree/InvenTree/backends.py

@@ -1,5 +1,6 @@
 """Custom backend implementations."""
 
+import datetime
 import logging
 import time
 
@@ -8,7 +9,6 @@ from django.db.utils import IntegrityError, OperationalError, ProgrammingError
 from maintenance_mode.backends import AbstractStateBackend
 
 import common.models
-import InvenTree.ready
 
 logger = logging.getLogger('inventree')
 
@@ -16,8 +16,7 @@ logger = logging.getLogger('inventree')
 class InvenTreeMaintenanceModeBackend(AbstractStateBackend):
     """Custom backend for managing state of maintenance mode.
 
-    Stores the current state of the maintenance mode in the database,
+    Stores a timestamp in the database to determine when maintenance mode will elapse.
-    using an InvenTreeSetting object.
     """
 
     SETTING_KEY = '_MAINTENANCE_MODE'
@@ -30,26 +29,45 @@ class InvenTreeMaintenanceModeBackend(AbstractStateBackend):
         """
         try:
             setting = common.models.InvenTreeSetting.objects.get(key=self.SETTING_KEY)
-            value = InvenTree.helpers.str2bool(setting.value)
+            value = str(setting.value).strip()
         except common.models.InvenTreeSetting.DoesNotExist:
             # Database is accessible, but setting is not available - assume False
-            value = False
+            return False
         except (IntegrityError, OperationalError, ProgrammingError):
             # Database is inaccessible - assume we are not in maintenance mode
-            logger.warning('Failed to read maintenance mode state - assuming True')
+            logger.debug('Failed to read maintenance mode state - assuming True')
-            value = True
+            return True
 
-        logger.debug('Maintenance mode state: %s', value)
+        # Extract timestamp from string
+        try:
+            # If the timestamp is in the past, we are now *out* of maintenance mode
+            timestamp = datetime.datetime.fromisoformat(value)
+            return timestamp > datetime.datetime.now()
+        except ValueError:
+            # If the value is not a valid timestamp, assume maintenance mode is not active
+            return False
 
-        return value
+    def set_value(self, value: bool, retries: int = 5, minutes: int = 5):
+        """Set the state of the maintenance mode.
 
-    def set_value(self, value: bool, retries: int = 5):
+        Instead of simply writing "true" or "false" to the setting,
-        """Set the state of the maintenance mode."""
+        we write a timestamp to the setting, which is used to determine
+        when maintenance mode will elapse.
+        This ensures that we will always *exit* maintenance mode after a certain time period.
+        """
         logger.debug('Setting maintenance mode state: %s', value)
 
+        if value:
+            # Save as isoformat
+            timestamp = datetime.datetime.now() + datetime.timedelta(minutes=minutes)
+            timestamp = timestamp.isoformat()
+        else:
+            # Blank timestamp means maintenance mode is not active
+            timestamp = ''
+
         while retries > 0:
             try:
-                common.models.InvenTreeSetting.set_setting(self.SETTING_KEY, value)
+                common.models.InvenTreeSetting.set_setting(self.SETTING_KEY, timestamp)
 
                 # Read the value back to confirm
                 if self.get_value() == value:

InvenTree/InvenTree/tests.py

@@ -19,6 +19,7 @@ import pint.errors
 from djmoney.contrib.exchange.exceptions import MissingRate
 from djmoney.contrib.exchange.models import Rate, convert_money
 from djmoney.money import Money
+from maintenance_mode.core import get_maintenance_mode, set_maintenance_mode
 from sesame.utils import get_user
 
 import InvenTree.conversion
@@ -1264,3 +1265,55 @@ class MagicLoginTest(InvenTreeTestCase):
         self.assertEqual(resp.url, '/api/auth/login-redirect/')
         # And we should be logged in again
         self.assertEqual(resp.wsgi_request.user, self.user)
+
+
+class MaintenanceModeTest(InvenTreeTestCase):
+    """Unit tests for maintenance mode."""
+
+    def test_basic(self):
+        """Test basic maintenance mode operation."""
+        for value in [False, True, False]:
+            set_maintenance_mode(value)
+            self.assertEqual(get_maintenance_mode(), value)
+
+        # API request is blocked in maintenance mode
+        set_maintenance_mode(True)
+
+        response = self.client.get('/api/')
+        self.assertEqual(response.status_code, 503)
+
+        set_maintenance_mode(False)
+
+        response = self.client.get('/api/')
+        self.assertEqual(response.status_code, 200)
+
+    def test_timestamp(self):
+        """Test that the timestamp value is interpreted correctly."""
+        KEY = '_MAINTENANCE_MODE'
+
+        # Deleting the setting means maintenance mode is off
+        InvenTreeSetting.objects.filter(key=KEY).delete()
+
+        self.assertFalse(get_maintenance_mode())
+
+        def set_timestamp(value):
+            InvenTreeSetting.set_setting(KEY, value, None)
+
+        # Test blank value
+        set_timestamp('')
+        self.assertFalse(get_maintenance_mode())
+
+        # Test timestamp in the past
+        ts = datetime.now() - timedelta(minutes=10)
+        set_timestamp(ts.isoformat())
+        self.assertFalse(get_maintenance_mode())
+
+        # Test timestamp in the future
+        ts = datetime.now() + timedelta(minutes=10)
+        set_timestamp(ts.isoformat())
+        self.assertTrue(get_maintenance_mode())
+
+        # Set to false, check for empty string
+        set_maintenance_mode(False)
+        self.assertFalse(get_maintenance_mode())
+        self.assertEqual(InvenTreeSetting.get_setting(KEY, None), '')