HTTP(S) monitors

Check a URL's status code, response time and body — with custom methods, headers, redirects, TLS verification and assertions.

An HTTP monitor makes a request to a URL and decides whether the response was good. It is the type most people start with.

Minimum setup

A URL and an interval. By default Glowo sends a GET, follows up to 5 redirects, verifies TLS, and treats any 2xx as healthy.

Request options

Option	Allowed values	Default
`method`	`GET`, `POST`, `PUT`, `PATCH`, `DELETE`, `HEAD`, `OPTIONS`	`GET`
`headers`	up to 20; names must be valid tokens, values max 4096 chars	none
`body`	up to 65536 characters (64 KiB)	none
`basicAuth`	`username` + `password`, 255 characters each	none
`followRedirects`	boolean	`true`
`maxRedirects`	0–10	5
`verifySsl`	boolean	`true`
`targetIp`	a valid IPv4 or IPv6 address	none

Header values may not contain carriage returns or line feeds — that is a response-splitting vector and is rejected at validation.

targetIp sends the request to a specific address while keeping the URL’s hostname in the Host header and TLS SNI. That lets you check one node behind a DNS round-robin, or verify a new server before you move DNS to it.

Deciding pass or fail

Expected status codes

expectedStatusCodes accepts up to 10 codes. Set it when a healthy response is not a 2xx — an endpoint that correctly returns 401 to an unauthenticated probe, for example.

Response-time thresholds

Option	Effect
`degradedAfterMs`	Slower than this → `DEGRADED`
`failedAfterMs`	Slower than this → `DOWN`

Both are independent of timeout. timeout is when Glowo gives up on the request entirely; these thresholds judge a response that did arrive.

Assertions

For anything about the body, headers or timing, use assertions — up to 20 per monitor, each able to mark the result DEGRADED or DOWN.

A worked example

Checking a JSON health endpoint that must return 200, respond within 800 ms, and report "status": "ok":

Method GET, URL https://api.example.com/health
Expected status codes 200
degradedAfterMs 800
Assertion — source json_body, property status, comparison equals, value ok, severity fail

Anything slower than 800 ms shows as degraded on your status page without paging anyone; a wrong status value pages you.