feature: the router makes scheduled backups to a local folder, copied to the cloud with rclone, or to a Proxmox Backup Server, and vpn-router-backup restores them.

debian-package/src/usr/lib/vpn-router/setup

@@ -63,6 +63,9 @@ MANAGER_PORT   = 7080
 #: The password of the metrics service account, which setup makes and keeps (root only).
 METRICS_SECRET = pathlib.Path('/etc/vpn-router/metrics.secret')
 
+#: The schedule of the backup timer, written from backup.schedule.
+BACKUP_SCHEDULE = pathlib.Path('/etc/systemd/system/vpn-router-backup.timer.d/schedule.conf')
+
 #: The configuration of Caddy, the HTTPS proxy, which the package's drop-in for caddy.service names;
 #: Caddy runs as the user and group CADDY_GROUP, which the caddy package creates.
 CADDYFILE   = pathlib.Path('/etc/caddy/vpn-router.Caddyfile')
@@ -566,6 +569,27 @@ def manage_metrics(ctx):
     run(['systemctl', 'restart', unit], check=False)
 
 
+def manage_backup(cfg):
+    """Run the backup timer on backup.schedule while backups are enabled, and stop it when not.
+
+    The schedule is a drop-in of the timer, BACKUP_SCHEDULE, which replaces the OnCalendar of the shipped unit.
+    """
+    unit = 'vpn-router-backup.timer'
+    if not cfg['backup']['enabled']:
+        run(['systemctl', 'disable', '--now', unit], check=False)
+        if BACKUP_SCHEDULE.exists():
+            BACKUP_SCHEDULE.unlink()
+            run(['systemctl', 'daemon-reload'], check=False)
+        return
+    text = f'[Timer]\nOnCalendar=\nOnCalendar={cfg["backup"]["schedule"]}\n'
+    if not BACKUP_SCHEDULE.exists() or BACKUP_SCHEDULE.read_text(encoding='utf-8') != text:
+        BACKUP_SCHEDULE.parent.mkdir(parents=True, exist_ok=True)
+        BACKUP_SCHEDULE.write_text(text, encoding='utf-8')
+        run(['systemctl', 'daemon-reload'], check=False)
+        run(['systemctl', 'restart', unit], check=False)
+    run(['systemctl', 'enable', '--now', unit], check=False)
+
+
 def run_platform_setup(cfg, ctx):
     """Let the platform module apply its own state, if it defines any."""
     module = vpnrouter.platform_module(cfg)
@@ -734,6 +758,8 @@ def main():
     refresh_web(cfg, ctx)
     progress('running', 'metrics service')
     manage_metrics(ctx)
+    progress('running', 'backup timer')
+    manage_backup(cfg)
     if problem:
         progress('failed', failed_step, problem)
         print(f'vpn-router: error: {problem}', file=sys.stderr)