Using composefs for filesystem?

Following the talk about composefs at FOSDEM - have you thought about using it for images and snaps?

It could help with deduplication and luckily snaps are read-only

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Side question, as I am not a snapd developer and I do not know enough about how snaps works.

But how would a composing/layered filesystem help?

For bandwith saves I think there is a mechanism for diffs between snap image updates in place.

And the snap files get mounted directly out of the squashfs images on start. Deduplication would have to happen afterwards. Maybe makes sense if you have a lot of old versions (or parallel versions) of one software around. Does neither sound like an embedded nor a common desktop use case.

Of course it would be great if it could bring size of cores and content snaps gnome/kde down. My guess would be that those do not share too many files of the same version.

May be you thought about a certain use case?

I image a composing filesystem is very useful for a tree like structure, but the structure of snap images is rather linear. Anyway would be interested in what the developers have to say

It seems to make heavy use of overlayfs, which traditionally didnt work well with apparmor confinement, not sure if that got solved upstream yet, but i remember it was a blocker in the past (we used to look at overlayfs for UbuntuCore back then)