Customizable reload URI

[keithherron]

In my deployment I'm loading the Pyrra filesystem generated recording rules using Thanos rule. It is working well so far with the exception of the automatic reload.

Pyrra logs "failed to reload Prometheus" and a manual reload is necessary to pick up rules when changes are made to Pyrra.

It'd be nice to have the ability to configure Pyrra with a customizable URI for the reload action, in my case it would be http://localhost:17902/rule/-/reload (which makes use of web.(route|external)-prefix feature)

[metalmatze]

Makes sense! We can add this via a flag on the filesystem component.

Funnily enough, I've used Pyrra with Thanos before, but it was using the Prometheus Operator to reload the configs, which is why I didn't encounter this myself.