Add timezone support for backup scheduling

Author: mrwogu

README.md

@@ -40,6 +40,18 @@ Files are backed up uncompressed by default, on the assumption a snapshotting or
 - `bz2`
 - `plain` (no compression - the default)
 
+## Timezone support
+
+You can now control the timezone used for scheduled backups by setting the `TZ` environment variable. For example:
+
+```yaml
+environment:
+  - TZ=Europe/Warsaw
+  - SCHEDULE=0 3 * * *
+```
+
+This ensures that the schedule is interpreted in the specified timezone. If `TZ` is not set, the system default timezone is used.
+
 ### Example `docker-compose.yml`
 
 ```yml

db-auto-backup.py

@@ -13,6 +13,7 @@
 
 import docker
 import pycron
+import pytz
 import requests
 from docker.models.containers import Container
 from dotenv import dotenv_values
@@ -158,6 +159,7 @@ def backup_redis(container: Container) -> str:
 
 BACKUP_DIR = Path(os.environ.get("BACKUP_DIR", "/var/backups"))
 SCHEDULE = os.environ.get("SCHEDULE", "0 0 * * *")
+TZ = os.environ.get("TZ")
 SHOW_PROGRESS = sys.stdout.isatty()
 COMPRESSION = os.environ.get("COMPRESSION", "plain")
 INCLUDE_LOGS = bool(os.environ.get("INCLUDE_LOGS"))
@@ -186,10 +188,24 @@ def get_container_names(container: Container) -> Iterable[str]:
     return names
 
 
+def get_localized_now(dt: datetime, tz_name: str) -> datetime:
+    tz = pytz.timezone(tz_name)
+    return dt.astimezone(tz)
+
+
 @pycron.cron(SCHEDULE)
 def backup(now: datetime) -> None:
     print("Starting backup...")
 
+    # Apply timezone if TZ is set
+    if TZ:
+        try:
+            tz = pytz.timezone(TZ)
+            now = now.astimezone(tz)
+        except Exception as e:
+            print(f"Invalid timezone '{TZ}': {e}")
+            sys.exit(1)
+
     docker_client = docker.from_env()
     containers = docker_client.containers.list()
 
@@ -253,7 +269,7 @@ def backup(now: datetime) -> None:
 
 if __name__ == "__main__":
     if os.environ.get("SCHEDULE"):
-        print(f"Running backup with schedule '{SCHEDULE}'.")
+        print(f"Running backup with schedule '{SCHEDULE}' (TZ={TZ}).")
         pycron.start()
     else:
         backup(datetime.now())

dev-requirements.txt

@@ -4,4 +4,5 @@ black==23.12.1
 ruff==0.11.8
 mypy==1.15.0
 types-requests
+types-pytz
 pytest==8.3.5

tests/tests.py

@@ -1,10 +1,12 @@
+from datetime import datetime
 from importlib.machinery import SourceFileLoader
 from importlib.util import module_from_spec, spec_from_loader
 from pathlib import Path
 from typing import Any, Callable
-from unittest.mock import MagicMock
+from unittest.mock import MagicMock, patch
 
 import pytest
+import pytz
 
 BACKUP_DIR = Path.cwd() / "backups"
 
@@ -130,3 +132,9 @@ def test_get_backup_provider(container_name: str, name: str) -> None:
 
     assert provider is not None
     assert provider.name == name
+
+def test_get_localized_now():
+    dt = datetime(2025, 5, 27, 12, 0, 0)
+    localized = db_auto_backup.get_localized_now(dt, "Europe/Warsaw")
+    assert localized.tzinfo is not None
+    assert localized.tzinfo.zone == "Europe/Warsaw"