Daemon Mode

vykar daemon runs scheduled backup cycles as a foreground process. Each cycle executes the default actions (backup → prune → compact → check) for all configured repositories, sequentially. The shutdown flag is checked between steps.

Scheduling: sleep-loop with configurable interval (schedule.every, e.g. "6h") or cron expression (schedule.cron, e.g. "0 3 * * *"). Optional random jitter (jitter_seconds) spreads load across hosts.
Passphrase: the daemon validates at startup that all encrypted repos have a non-interactive passphrase source (passcommand, passphrase, or VYKAR_PASSPHRASE env). It cannot prompt interactively.
Scheduler lock: the daemon and GUI share a process-wide scheduler lock under the local config directory so only one scheduler is active at a time. On Unix this uses flock(2) and is released automatically on process exit.

Configuration:

schedule:
  enabled: true
  every: "6h"                  # fixed interval
  # cron: "0 3 * * *"         # OR 5-field cron (mutually exclusive with every)
  on_startup: false
  jitter_seconds: 0

Config reload via SIGHUP

Send SIGHUP to the daemon process to reload the configuration file without restarting:

kill -HUP $(pidof vykar)

Reload behavior:

The reload takes effect between backup cycles — a cycle in progress runs to completion first
on_startup is ignored on reload; next_run is recalculated from the schedule relative to now
If the new config is invalid (parse error, empty repositories, schedule.enabled: false, passphrase validation failure), the daemon logs a warning and continues with the previous config
If the new config is valid, repos and schedule are replaced and the next run time is recalculated

Ad-hoc backup via SIGUSR1

Send SIGUSR1 to the daemon to trigger an immediate backup cycle:

kill -USR1 $(pidof vykar)

The cycle runs between scheduled backups — a cycle in progress runs to completion first, then the triggered cycle starts
The existing schedule is preserved when the ad-hoc cycle finishes before the next scheduled slot; if it overruns the slot, the next run is recalculated from the current time (same as after any regular cycle)
With systemd: systemctl kill -s USR1 vykar

Deployment

systemd

Create a unit file at /etc/systemd/system/vykar.service:

[Unit]
Description=Vykar Backup Daemon
After=network-online.target
Wants=network-online.target

[Service]
Type=simple
ExecStartPre=+/bin/mkdir -p %h/.cache/vykar %h/.config/vykar
ExecStart=/usr/local/bin/vykar --config /etc/vykar/config.yaml daemon
ExecReload=/bin/kill -HUP $MAINPID
Restart=on-failure
RestartSec=60

# Security hardening
NoNewPrivileges=true
ProtectSystem=strict
ProtectHome=read-only
ReadWritePaths=%h/.cache/vykar %h/.config/vykar
# If backing up to a local path, add it here too, e.g.:
# ReadWritePaths=%h/.cache/vykar %h/.config/vykar /mnt/backup/vykar
PrivateTmp=true
PrivateDevices=true

# Passphrase via environment file (optional)
# EnvironmentFile=/etc/vykar/env

[Install]
WantedBy=multi-user.target

Local repositories: the ProtectSystem=strict directive makes the filesystem read-only by default. If any repository target is a local path, add it to ReadWritePaths or the backup will fail with “Read-only file system”.

Then enable and start:

systemctl daemon-reload
systemctl enable --now vykar

Reload configuration after editing the config file:

systemctl reload vykar

Check status and logs:

systemctl status vykar
journalctl -u vykar -f

Docker

The default Docker entrypoint runs vykar daemon. See Installing — Docker for container setup, volume mounts, and Docker Compose examples. To reload configuration in a running container:

docker kill --signal=HUP vykar-daemon
# or with Compose:
docker compose kill -s HUP vykar

To trigger an immediate backup:

docker kill --signal=USR1 vykar-daemon
# or with Compose:
docker compose kill -s USR1 vykar