In the past year I moved our teams entire infrastructure monitoring from Nagios/collectd to Prometheus. The amount of visibility into our infrastructure it has provided that we didn’t have before has been invaluable.
We host a bunch of small WordPress and other custom built websites (along with a couple very large sites) that we use the Blackbox exporter to monitor the response code and SSL Certificate status. I wanted to be able to keep all the sites we monitored in two files without having to modify the prometheus.yml every time I needed to add or remove a site which could require a reload of Prometheus.
I ended up using the file based service discovery for this. I had to dig quite a bit to find an example (which I think I found in a Github issue). Someday I want to expand this to use proper service discovery (like we do for all the other exporters) but I wanted something simple to start.
Below is examples how I have this setup in the Prometheus and Blackbox exporter configs.
1) Add the blackbox exporter job to the prometheus.yml file:
2) Then we need to configure the Blackbox Exporter on how to handle our two config files (one for http one for https):
3) Finally our last two configs. These are the actually lists of sites that the blackbox exporter will be monitoring.
That should be it. Any changes you make to either of the http_2xx.yml or https_2xx.yml config will automatically be picked up by Prometheus based on your scrape_interval setting.
Feel free to give me a shout if you have any questions or issues.