Add a module which will create notifications for all users when the license is at its expiration period, and terminate the process when the license expires.

util/expiration.py

@@ -0,0 +1,76 @@
+import calendar
+import sys
+
+from email.utils import formatdate
+from apscheduler.scheduler import Scheduler
+from datetime import datetime, timedelta
+
+from data import model
+
+
+class ExpirationScheduler(object):
+  def __init__(self, utc_create_notifications_date, utc_terminate_processes_date):
+    self._scheduler = Scheduler()
+    self._termination_date = utc_terminate_processes_date
+
+    soon = datetime.now() + timedelta(seconds=1)
+
+    if utc_create_notifications_date > datetime.utcnow():
+      self._scheduler.add_date_job(model.delete_all_notifications_by_kind, soon,
+                                   ['expiring_license'])
+
+      local_notifications_date = self._utc_to_local(utc_create_notifications_date)
+      self._scheduler.add_date_job(self._generate_notifications, local_notifications_date)
+    else:
+      self._scheduler.add_date_job(self._generate_notifications, soon)
+
+    local_termination_date = self._utc_to_local(utc_terminate_processes_date)
+    self._scheduler.add_date_job(self._terminate, local_termination_date)
+
+  @staticmethod
+  def _format_date(date):
+    """ Output an RFC822 date format. """
+    if date is None:
+      return None
+    return formatdate(calendar.timegm(date.utctimetuple()))
+
+  @staticmethod
+  def _utc_to_local(utc_dt):
+    # get integer timestamp to avoid precision lost
+    timestamp = calendar.timegm(utc_dt.timetuple())
+    local_dt = datetime.fromtimestamp(timestamp)
+    return local_dt.replace(microsecond=utc_dt.microsecond)
+
+  def _generate_notifications(self):
+    for user in model.get_active_users():
+      model.create_unique_notification('expiring_license', user,
+                                       {'expires_at': self._format_date(self._termination_date)})
+
+  @staticmethod
+  def _terminate():
+    sys.exit(1)
+
+  def start(self):
+    self._scheduler.start()
+
+
+class Expiration(object):
+  def __init__(self, app=None):
+    self.app = app
+    if app is not None:
+      self.state = self.init_app(app)
+    else:
+      self.state = None
+
+  def init_app(self, app):
+    expiration = ExpirationScheduler(app.config['LICENSE_EXPIRATION_WARNING'],
+                                     app.config['LICENSE_EXPIRATION'])
+    expiration.start()
+
+    # register extension with app
+    app.extensions = getattr(app, 'extensions', {})
+    app.extensions['expiration'] = expiration
+    return expiration
+
+  def __getattr__(self, name):
+    return getattr(self.state, name, None)