Is there an existing issue for this?

• There is no existing issue for this feature

What are you currently unable to do

incus export, and more generally the backup API, writes the exported tarballs on disk. In scenarios where we do not have enough space on disk or where we would like to process the data stream with low latency, this intermediate step is problematic.

What do you think would need to be added

There are several ways to see this:

• a direct flag in the backup API endpoint allowing the data to be exported on demand through /export without dumping to disk, to minimize friction with the existing clients,
• a new GET API endpoint that behaves like /export but without a backup ID, exporting data on the go.

incus export should also use this feature