systemd timers are the modern replacement for cron on Linux systems. Like cron jobs, they fail silently by default. Alert24 heartbeat checks give you visibility: if a timer stops firing or its service exits with an error, Alert24 creates an incident.

Before you start

In Alert24, go to Monitoring → Add check → Heartbeat
Give it a name matching your service (e.g., "Data sync timer")
Set the Expected interval to match your timer's OnCalendar or OnBootSec frequency
Set a Grace period (300 seconds is a safe default for hourly-or-less timers)

Save — you'll get a heartbeat URL:

https://app.alert24.net/api/hb/YOUR_TOKEN

Add the ping to your service unit

Edit your service file (/etc/systemd/system/your-job.service) and add an ExecStartPost directive:

[Unit]
Description=Daily data sync
After=network.target

[Service]
Type=oneshot
User=app
ExecStart=/usr/local/bin/sync-data.sh
ExecStartPost=/bin/bash -c 'curl -fsS --retry 3 https://app.alert24.net/api/hb/YOUR_TOKEN || true'

[Install]
WantedBy=multi-user.target

The ExecStartPost line runs after ExecStart exits. Use || true to prevent the post step from masking the exit code of the main command.

Important: ExecStartPost only runs if ExecStart exits with code 0. If your service fails, no ping is sent — which is the correct behavior. Alert24 fires an incident after the grace period expires.

Alternative: OnSuccess handler (systemd 250+)

If you're on a recent systemd version, use OnSuccess to chain a ping unit:

# your-job.service
[Unit]
Description=Daily data sync
[email protected]

[Service]
Type=oneshot
ExecStart=/usr/local/bin/sync-data.sh

# /etc/systemd/system/[email protected]
[Unit]
Description=Alert24 heartbeat ping for %i

[Service]
Type=oneshot
ExecStart=/usr/bin/curl -fsS --retry 3 https://app.alert24.net/api/hb/%i

Your timer file stays unchanged

# your-job.timer
[Unit]
Description=Run data sync daily

[Timer]
OnCalendar=daily
Persistent=true

[Install]
WantedBy=timers.target

Reload and restart after changes:

systemctl daemon-reload
systemctl restart your-job.timer

Tips

journalctl -u your-job.service: Use this to view logs if the service fails and the ping is never sent.
Persistent=true: With this set, if the system was off when the timer was supposed to fire, it runs immediately on next boot. Alert24's grace period accommodates brief system downtime — set it longer than your typical maintenance window.
Multiple services: Create one Alert24 heartbeat check per timer service. The [email protected] pattern (Option 2) makes it easy to add a ping to any service without duplicating configuration.