Critic is a very simple web monitoring tool. It periodically (every 30 seconds) polls URLs provided as values of environment variables with the name prefix WATCH_ and exports them as prometheus metrics.

Following metrics are exported for each target:

The value of this metric will be set to 1 if the probe deems target to be healthy. Target is assumed to be healthy when the HTTP request succeeds with the stats code between 100 and 499, excluding 404.

This counter increases every time probe for the target fails (either can't connect or the status code is > 500 or 404)

Request duration of the last probe in seconds.

Unix time of the TLS Certificate expiration. This metric will be exported only for server URLs with https scheme.

HTTP Status code of the last probe. If creating request has failed, value will be 0. In the case that performing request has failed, the value will be 1.