Slack alerts

Post a message to Slack when a rule changes state.

Uptimer sends alerts through one webhook per workspace. Point it at a Slack incoming webhook and you get a message in your channel whenever a rule flips up → down (or recovers).

Set it up

1. In Slack, create an Incoming Webhook and copy its URL.
2. In Uptimer, open Workspace → Settings → Webhook URL, paste it, and save.

On the next status change, Uptimer POSTs a Slack-formatted message — green when a rule recovers, red when it goes down — with a link back to the rule’s history.

Alerts fire on state transitions, not on every check: one message when a rule goes down, one when it recovers — not one per interval.

The webhook is configured in the dashboard (not the REST API), and there is one URL per workspace. It covers every rule in that workspace — there is no per-rule switch: set the URL and all rules alert. To send somewhere other than Slack, see Webhooks.

When an alert actually fires

An alert is sent on a status transition, so Uptimer must already have a status to change from. That has a few consequences worth knowing when you’re testing:

• A brand-new rule’s first check only records its starting status — no alert is sent for it.
• So a rule that is down from the moment you create it never alerts — it has no healthy baseline to fall from. Point a new rule at a healthy URL first, let it go Up, and it will then alert on the next real outage.
• Give it at least two check intervals (≥ 2 minutes at the default one-minute cadence) to produce the first transition.
• A rule stuck at No Data (no region assigned) never alerts — it isn’t being checked at all.

The webhook is called from the Uptimer server (or its container), so the URL must be reachable from there — a localhost receiver on your laptop is not reachable from inside the container. If nothing arrives, check the server logs for the outgoing webhook POST.

Delivery is best-effort. Uptimer sends the webhook once, in the background — there is no delivery-status indicator, retry, or “send test” button yet, and a failed POST is recorded only in the server logs, not the dashboard. If alerts don’t arrive and the URL is reachable, the logs are the place to look.