root: implement db backups with monitored task, update docs

passbook/lib/tasks/backup.py

@@ -0,0 +1,34 @@
+"""Database backup task"""
+from datetime import datetime
+from io import StringIO
+
+from botocore.exceptions import BotoCoreError, ClientError
+from django.contrib.humanize.templatetags.humanize import naturaltime
+from django.core import management
+from structlog import get_logger
+
+from passbook.lib.tasks import MonitoredTask, TaskResult, TaskResultStatus
+from passbook.root.celery import CELERY_APP
+
+LOGGER = get_logger()
+
+
+@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) as exc:
+        self.set_status(TaskResult(TaskResultStatus.ERROR).with_error(exc))