On 4/18/24 12:35, Fiona Ebner wrote:
Am 18.04.24 um 11:27 schrieb Dominik Csapak:
ok after a bit of thinking and discussing off-list
the plan to go forward from my side is this:
(please tell if there is something obviously wrong with it or you'd
strongly prefer something differently)
extract on demand vs on upload:
i'd go with extract on demand because managing the extraction of the
tarball + subdir etc is not really a win in my book, since we have to
have most safeguards anyway and we have the same
issue of where to store/map it etc. also it's not convenient for users
that have already
a bunch of ovas and want to store them in a central place, now they'd
have to extract
them just for us (and importing should be as small a hassle as it can be)
The upside is that it would avoid all the extra cleanup handling and be
more efficient for users that want to import from a single OVA multiple
times. But you are right, the downside is also very big.
I'm thinking now, is there no way to expose a file in an OVA/tar without
actually extracting it? I.e. something like
root@pve8a1 ~ # cat B
secret
root@pve8a1 ~ # tar cf arch.tar A B dir
root@pve8a1 ~ # losetup --offset 1536 --sizelimit 512 --read-only --show -f
arch.tar
/dev/loop0
root@pve8a1 ~ # cat /dev/loop0
secret
but that doesn't seem to work with sizelimit < 512. Not claiming losetup
is a good mechanism for that, just to illustrate the idea.
AFAIU that only works for uncompressed tars and ova can by definition
be compressed, so that won't work reliably
there is archivemount[0], which can fuse mount archives
i tested that, and it's *very* slow for randomly accessing the files inside
(i guess because it must seek much further back to get the compression
state correct)
i tested a qemu-img convert from such a file and it took >10 minutes
for a file that would normally be extracted + converted in under a minute
0: https://github.com/cybernoid/archivemount
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