SSL/HTTP-Check Reference

Configuration options for HTTP endpoint and certificate monitoring

Written By Erdinc Akay

Last updated 26 days ago

Configuration fields

Field	Type	Required	Default	Description
URL	string	Yes	—	The full HTTP or HTTPS address to monitor
Expected status code	integer	No	200	The HTTP status code the site should return. Common codes: 200 (OK), 301 (Redirect), 403 (Forbidden)
Check SSL certificate expiry	boolean	No	true	Monitor the SSL/TLS certificate expiration date
Warning threshold (days before expiry)	integer	No	30	Trigger a warning if the certificate expires within this many days. Only shown when Check SSL certificate expiry is enabled.
Error threshold (days before expiry)	integer	No	14	Trigger an error if the certificate expires within this many days. Only shown when Check SSL certificate expiry is enabled.

Multiple endpoints can be added to a single check. Each endpoint is evaluated independently.

Field	Description
Status code	The HTTP status code returned by the site (0 if the connection failed entirely)
Status code match	Whether the returned code matches the expected code
Certificate subject	The domain name on the certificate. Only shown when the certificate is within the warning or error threshold.
Days remaining	How many days until the certificate expires
Response time (ms)	How long the request took, in milliseconds
Result	OK, Warning, Critical, or Error (shown when the endpoint could not be reached) for this endpoint

Priority	Condition
Error	An endpoint is unreachable (connection failed or timed out)
Critical	An endpoint returns the wrong status code, or the certificate expires within the error threshold
Warning	An endpoint's certificate expires within the warning threshold
OK	All endpoints are reachable, return expected codes, and certificates are not near expiration

Each request has a 30-second timeout. If the site does not respond within that time, the check reports an error.
The check does not follow redirects. If a site redirects, enter the final URL to ensure the correct certificate is checked.
The certificate check retrieves the certificate from the server without validating the full trust chain. This means expired or self-signed certificates are still checked for their expiration rather than being rejected outright.
If the warning threshold is set lower than the error threshold, the check silently swaps the two values at runtime. Configuring 14/30 (inverted) behaves the same as 30/14.
If the check has no endpoints configured, it returns a Warning result and the detail view shows "No endpoints monitored."

See also: Configure an SSL/HTTP-Check