HTTP monitors

What it checks

Requests a URL on a schedule and decides success from three things, in order:

The request completed within the timeout
The response status is in your accepted set
The keyword assertion passes, if you set one

Any of them failing counts as one failed check.

Fields

Field	Range	Default	Notes
URL	up to 2048 chars	—	`http` or `https` only
Interval	20 s – 24 h	60 s
Timeout	1 – 60 s	10 s	Whole request
Failures before down	1 – 10	2
Accepted status	codes and ranges	`200`	e.g. `200-299,301`
Max redirects	0 – 10	0	0 = do not follow
Keyword	up to 200 chars	none
Keyword inverted	on / off	off	Fail if the keyword is present
Re-alert every	5 min – 24 h, or off	off
Second opinion	on / off	on

Accepted status expressions

A comma-separated list of codes and inclusive ranges:

200
200-299
200-299,301
200,204,301-302

Whitespace is ignored, so 200-299 , 301 is fine. A reversed range (299-200) is rejected at save time rather than silently never matching.

Use a range, not a single code. 200 alone means a 204 No Content health endpoint pages you at 3am for working correctly.

Redirects

0 means do not follow — the redirect status itself is what gets checked. Combine with an accepted status of 301 to assert that a URL does redirect:

URL:             http://example.com/
Accepted status: 301
Max redirects:   0

That monitor fails if the redirect ever stops happening — which is the actual thing you wanted to know.

Set a non-zero value to follow to the final response. Each hop counts against the timeout.

Keyword assertions

After the status check, assert on the response body.

Normal — the body must contain the keyword. Use a marker that only appears when the page genuinely rendered: a heading, a nav item, or something that appears after the database call. Do not use text from a template shell that renders even when the app is broken.

Inverted — the body must not contain the keyword. Use for error markers: Application error, 502 Bad Gateway, Under maintenance.

The first 256 KB of the body is read. Anything past that is not searched, so put your marker where it will actually appear.

An empty keyword means no assertion. Clearing the field removes the assertion rather than matching an empty string.

Failure messages

status 503 (accepted: 200-299)
body does not contain "ready"
body contains "Application error"
connect failed: Connection refused (os error 111)
dns error: failed to lookup address information
timed out after 10000ms

Restrictions

Private-network targets are refused unless the deployment explicitly opts in. That covers loopback, RFC1918, link-local including the cloud metadata address, and CGNAT ranges, with the IPv6 equivalents.

Credentials in the URL are rejected. https://user:pass@example.com/ is refused, because those credentials would be sent to the target on every check. Use a header-free health endpoint, or a token in the path.

Only http and https.

Worked example

Monitoring an API health endpoint that returns 204 and sits behind a redirect:

URL:                  https://api.example.com/health
Interval:             60 s
Timeout:              10 s
Accepted status:      200-299
Max redirects:        2
Keyword:              (none — a 204 has no body)
Failures before down: 2
Re-alert every:       30 min