core: fix backup task not being registered, add fallback for api to remove info on ImportError

celery only discovers tasks from installed apps, which `lib` is not, hence the schedule didn't trigger it

passbook/core/tasks.py

@@ -1,4 +1,11 @@
 """passbook core tasks"""
+from datetime import datetime
+from io import StringIO
+
+from boto3.exceptions import Boto3Error
+from botocore.exceptions import BotoCoreError, ClientError
+from django.contrib.humanize.templatetags.humanize import naturaltime
+from django.core import management
 from django.utils.timezone import now
 from structlog import get_logger
 
@@ -24,3 +31,24 @@ def clean_expired_models(self: MonitoredTask):
         LOGGER.debug("Deleted expired models", model=cls, amount=amount)
         messages.append(f"Deleted {amount} expired {cls._meta.verbose_name_plural}")
     self.set_status(TaskResult(TaskResultStatus.SUCCESSFUL, messages))
+
+
+@CELERY_APP.task(bind=True, base=MonitoredTask)
+def backup_database(self: MonitoredTask):  # pragma: no cover
+    """Database backup"""
+    try:
+        start = datetime.now()
+        out = StringIO()
+        management.call_command("dbbackup", quiet=True, stdout=out)
+        self.set_status(
+            TaskResult(
+                TaskResultStatus.SUCCESSFUL,
+                [
+                    f"Successfully finished database backup {naturaltime(start)}",
+                    out.getvalue(),
+                ],
+            )
+        )
+        LOGGER.info("Successfully backed up database.")
+    except (IOError, BotoCoreError, ClientError, Boto3Error) as exc:
+        self.set_status(TaskResult(TaskResultStatus.ERROR).with_error(exc))