How do volumes work in v2 apps?

[thewilkybarkid]

I migrated a couple apps with volumes yesterday. Since the volumes only containing caches, I tried to avoid downtime by removing them manually, migrating then adding new volumes. I ran into the same problem at the last step.

I found it difficult to understand what to do, and after trying the attach-volume switch (which I couldn’t get to work) and some investigation into the scary-looking machines API I found

Some issues with Volumes on Apps v2

I still cannot seem to add a volume to my app. I’ve tried everything in this thread. I keep getting the error: Error: machine [id goes here] [app] does not have a volume configured and fly.toml expects one with destination /volume; remove the [mounts] configuration in fly.toml or use the machines API to add a volume to this machine After adding a [mounts] section to my fly.toml and redeploying the app. Also, when running fly volumes list, the volume’s “ATTACHED VM” column is empty, no matter…

So I followed that and scaled them down to 0 (so much for no downtime!), then ran a deploy and it created a new machine with the volume attached. I could then clone it to scale back up. It all seems to be ok now.