FlyBackend supports mounting volume

[LiboShen]

I'm using FLAME for my project to run ML workload running on Fly. To avoid download the 4GB model data every time starting a FLAME runner, a Fly volume needs to be attached to the instance.

Currently there is a PR #22 by @benbot, however, it seems abandoned for 3 months.

Token a brief look, the tricky part seems that:

• Fly volumes don't auto-scale when creating new instance,
• and the API requires the caller to explicit specify the volume id instead of just the name.

This might become trickier when multiple nodes in the cluster trying to start the runners at the startup time causing potential race condition.

I currently forked the FlyBackend and hardcoded the volume info to make things working in my project. But a proper built-in solution would be very nice.

[benbot]

I’ve been working off of my fork for a while, just haven’t had the need to update it yet.

despite being open for a few months, it got very little attention, so I’m not sure what the plan is for volumes with FLAME.

you could modify the backend further (it’s actually really simple) to use the fly api to create volumes on the fly, but that’d be very slow.

IMO this kind of functionality should be on fly and not in flame.

that being said I’m open to adding/changing anything in my PR if it’d help :)