Monitoring Cloudflare sites should just work out of the box but there are a few things to keep in mind.
The IP addresses we monitor from do not change often and we have an up-to-date list, as well as a prebuilt Cloudflare WAF expression rule.
We also use our own user-agent to identify ourselves in your logs.
Note: if you proxy all requests (ie: don't cache in Cloudflare), the source you'll see on your server(s) could still be Cloudflare.
Monitor the backend
In general, it's good to monitor your site twice:
- The standard setup as you normally would,
- Using a secret query string in the URL or a secret header, to be configured in Cloudflare to always send to your backend.
This way Oh Dear can monitor both Cloudflare and your backend is working, just in case Cloudflare returns a cached response but your backend is offline.
Keep your cache warm
Check out this blog post showing you how to use the broken links crawler and varnish to keep you cache warm!