Alert rules
Every alert rule type DownCTL supports, which ones need a threshold, and which checks they're based on.
Alert rules decide when you get notified. Alert channels decide where — a rule can target one or more channels at once.
Rule types
| Rule | Based on | Threshold |
|---|---|---|
| Site down | Uptime checks — automatic, every minute | None |
| Slow response | Response time on every uptime check | Milliseconds (e.g. 3000) |
| CPU usage | Server metrics | Percent (e.g. 90) |
| Memory usage | Server metrics | Percent (e.g. 85) |
| Disk usage | Server metrics | Percent (e.g. 80) |
| Error rate | Error tracking | Error count in a time window |
| SSL certificate expiring | Automatic daily SSL check | Days remaining (e.g. 14) |
| Domain registration expiring | Automatic daily domain check | Days remaining (e.g. 30) |
| DNS resolution failure | Automatic daily DNS check | None |
| IP blacklist listing | Automatic daily blacklist check | None |
| API monitor failing | API monitors | None |
| Cron job failing | Cron monitors | None |
| Ping unreachable | Ping monitoring | None |
| Port monitor down | Port monitors | None |
Rules without a threshold fire as soon as the underlying check fails — there's nothing to configure beyond picking which channels to notify.
Setting up a rule
- Open a site's Alerts tab and click New rule.
- Pick a rule type from the table above.
- If it requires a threshold, enter the value — DownCTL shows the unit (%, ms, days) automatically.
- Error rate rules also need a time window (e.g. "10 errors in 5 minutes").
- Choose one or more alert channels to notify.
- Save. The rule takes effect on the next check.
What's automatic vs. what you set up
Site down, slow response, SSL expiring, domain expiring, DNS failure, and blacklist listing are all based on checks that run automatically the moment you add a site — you only need to create the alert rule, not the underlying check. CPU/memory/disk require the server agent to be installed first. Error rate requires error tracking to be wired up. API monitor, cron job, ping, and port rules require you to create that monitor first.