I’ve been running an instance of uptime-kuma on fly.io for a while now. Their CLI makes it easy to deploy simple container applications and you can use up to three instances with 256MB of RAM and 3GB of persistent storage for free.

A few days ago I got an email saying that my monthly bill would have been 41 cents, but since they don’t collect bills under $5, they’re giving me a 100% discount. Which is nice, but I wondered where the 41 cents came from, so I logged on to their dashboard. And it turns out that a new data volume was created four weeks ago. And because I now have two 3GB volumes instead of one, I was being charged for the usage.

I think I may have created the second volume during a migration to their new v2 instances.

So if you also use fly.io you should check your dashboard and remove unused (and empty) volumes. This can be done with a simple flyctl volumes list followed by a flyctl volumes destroy vol_123.