http_check — HTTP(S) checks with TLS expiry

Free tier. Checks a list of URLs every cycle: status validation, latency broken down by phase (DNS, connect, TLS handshake, time-to-first-byte, total), response size, optional content matching — and the remaining validity of the TLS certificate as a first-class metric.

Quick start

# probes.d/30-web.yaml
- name: web-checks
  type: http_check
  params:
    targets:
      - "https://www.example.com"
      - "https://api.example.com/healthz"
    interval: 60

Parameters

Parameter	Must set	Default	Description
targets	Yes	-	URLs to check. Example: https://app.example.com/health
method	No	GET	HTTP method. One of GET, HEAD, POST, PUT, DELETE, OPTIONS, PATCH
timeout	No	10	Whole-request budget in seconds
interval	No	60	Seconds between cycles
expected_status	No	-	Exact status that counts as up; empty means any 2xx or 3xx
content_match	No	-	Regular expression the body must match. Example: "status":"ok"
insecure_skip_verify	No	false	Accept self-signed certificates

insecure_skip_verify is for a lab, not for production. Targets are checked in parallel (bounded). Redirects are reported, not followed: a 301 is the measured answer of the target.

Metrics

One series per metric per target (target tag).

Metric	Unit	Description
senhub.httpcheck.up	bool	Expected status (and content, if configured)
senhub.httpcheck.status.code	code	Last response status
httpcheck.duration	s	Total request time
senhub.httpcheck.duration.dns / .connect / .tls / .ttfb	ms	Phase breakdown
senhub.httpcheck.response.size	B	Body size (1 MiB read cap)
senhub.httpcheck.tls.expiry	days	Days until the certificate expires — negative once expired. Alert under 30
senhub.httpcheck.content.match	bool	Only when content_match is configured

A failing or unreachable target is a measurement (up = 0), never a probe failure.

Metric reference

Every metric this probe can emit. Metric is the OpenTelemetry name the OTLP, Prometheus and Zabbix outputs derive theirs from. Name is what a Nagios check and the API metrics= filter match. PRTG channel is the label PRTG shows, placeholders filled from the series' tags.

Metric	Name	PRTG channel	Unit	Description
senhub.httpcheck.up	senhub.httpcheck.up	HTTP {target} Up	#	1 when the target answered with the expected status (and content, if configured)
senhub.httpcheck.status.code	senhub.httpcheck.status.code	HTTP {target} Status Code	#	HTTP status code of the last response
httpcheck.duration	httpcheck.duration	HTTP {target} Total Time	ms	Wall-clock time of the whole request
senhub.httpcheck.duration.dns	senhub.httpcheck.duration.dns	HTTP {target} DNS Time	ms	DNS resolution phase
senhub.httpcheck.duration.connect	senhub.httpcheck.duration.connect	HTTP {target} Connect Time	ms	TCP connect phase
senhub.httpcheck.duration.tls	senhub.httpcheck.duration.tls	HTTP {target} TLS Handshake Time	ms	TLS handshake phase (HTTPS targets only)
senhub.httpcheck.duration.ttfb	senhub.httpcheck.duration.ttfb	HTTP {target} Time To First Byte	ms	Time from request start to the first response byte
senhub.httpcheck.response.size	senhub.httpcheck.response.size	HTTP {target} Response Size	B	Response body size (capped at 1 MiB read)
senhub.httpcheck.tls.expiry	senhub.httpcheck.tls.expiry	HTTP {target} Certificate Days Left	#	Days until the leaf certificate expires (negative once expired)
senhub.httpcheck.tls.valid	senhub.httpcheck.tls.valid	HTTP {target} Certificate Valid	#	1 when the leaf TLS certificate is currently valid (not expired), 0 otherwise
senhub.httpcheck.content.match	senhub.httpcheck.content.match	HTTP {target} Content Match	#	1 when the configured content_match regexp matched the response body