How to Monitor Cron Jobs
Cron jobs silent-fail — the most common cause of data loss. Default cron: on error, email (if SMTP set up), otherwise nothing. Right approach: heartbeat monitoring (dead-man's switch) — cron pings a URL on success, monitoring service waits for a ping and alerts if missed. Solutions: Enterno Heartbeat, Healthchecks.io, Cronitor.
Below: step-by-step, working examples, common pitfalls, FAQ.
Step-by-Step Setup
- Create a heartbeat monitor at Enterno Heartbeat → get a unique ping URL
- Add curl to the end of your cron line:
5 2 * * * /usr/bin/backup.sh && curl -fsS PING_URL - For logging failures:
curl -fsS PING_URL/failon the error path - Set expected interval (hourly = 60 min grace period)
- Configure alerts: Email/Telegram/Slack on missed ping
- Verify: comment the cron → after expected time you get an alert
- For batch jobs: ping /start at the beginning + /PING_URL at end → measures duration
Working Examples
| Scenario | Config |
|---|---|
| Simple success ping | 0 3 * * * /usr/local/bin/backup.sh && curl -fsS https://heartbeat.enterno.io/ping/abc123 > /dev/null |
| Ping with duration | 0 3 * * * curl -fsS -m 10 https://heartbeat.enterno.io/start/abc123 &&
/usr/local/bin/backup.sh &&
curl -fsS https://heartbeat.enterno.io/ping/abc123 |
| Fail ping on error | 0 3 * * * /backup.sh || curl -fsS https://heartbeat.enterno.io/fail/abc123 |
| With exit code | 0 3 * * * (/backup.sh; STATUS=$?; curl -fsS https://heartbeat.enterno.io/ping/abc123/$STATUS) |
| Systemd timer alternative | # /etc/systemd/system/backup.service
[Service]
ExecStart=/backup.sh
ExecStartPost=curl -fsS https://heartbeat.enterno.io/ping/abc123 |
Common Pitfalls
- curl missing -fsS flags — silent fail on 500, nothing pings
- Grace period too low — false positives on short cron delays
- && between commands: if backup fails, ping skips — that's correct for alerting
- Ping URL in a git repo — others can ping and hide real failures
- Multi-step pipeline: needs heartbeat per step, not just the final one
Why teams trust us
How it works
Create heartbeat
Ping URL from cron
Get alert on miss
What is Heartbeat Monitoring?
A heartbeat monitor is a "reverse monitor": instead of us polling the service, the service signals us that it's alive. If no signal arrives within the set interval — we send an alert.
Simple Integration
One GET request to a unique URL — and the monitor knows the job completed.
Grace Period
Set an acceptable ping delay to avoid false alerts.
Smart Notifications
Email and Telegram on missed ping. Repeated alert if silence continues.
Execution History
Full ping log with timestamps — see every job execution.
Who uses this
DevOps
cron job monitoring
Developers
background worker check
Sysadmins
dead man's switch
Business
payment queue monitoring
Common Mistakes
Best Practices
curl -s https://enterno.io/api/heartbeat/TOKEN — simple and reliable.Start monitoring cron for free
Heartbeat monitor: 5 tasks free, Telegram and email alerts on missed runs.
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How-to
Frequently Asked Questions
Cron sends email by default — isn't that enough?
Often SMTP isn't configured on a VPS → email never lands. Heartbeat actively alerts when cron didn't start at all (host down, cron daemon stopped).
Healthchecks.io vs Enterno?
Healthchecks — open-source + SaaS free tier. Enterno — integrated with uptime/SSL/DNS monitoring in one dashboard, + RU servers.
Kubernetes CronJob — how?
Same principle: <code>curl PING_URL</code> in postStart/postStop container lifecycle hook. Or a sidecar container.
Private network cron — how to ping?
Outbound HTTP is usually allowed. If not — self-hosted Healthchecks on internal network.