Access other container's mounts while keeping permissions


I have multiple websites instances and each one has its own unprivileged container. Website data is at /web directory that is an unshifted mount from the host. At host I can the files are owned by some user at eg. /mnt/NVME1/webdata/site1 that represents the www-data user of the container.

In order to provide FTP access to the files of each website I’m running Pure-FTPd on the host. I can define users for FTP access, point them at the appropriate host’s folder where each website’s data is stored and tell it to read/write files with the specific UID/GID that matches the www-data of the container.

Now, I want to move Pure-FTPd to its own container, how can I keep it unprivileged and mount the folder where all the websites are stored while keeping the users UID/GID as the host seems them?

If I simply add a device like:

lxc config device add pureftpd webdata disk source=/mnt/NVME1/webdata path=/mnt/webdata

They’ll all show up as nobody:nogroup. What can I do here?

Thank you.