A script and classes for generating UID and GID mappings for unprivileged LXC containers because it's a pain in the arse to do by hand.
Now manages multiple UIDs and GIDs as well as ranges to transpose.
./lxc-idmap.rb and follow the prompts. You could roll your own i/f around the LxcIdMap class as well.
You can enter your UIDs and UID ranges using this format:
501 890-899 2084-2525 4000 4040
and same again for your GIDs.
It doesn't support transposing a container UID you specify to a different host UID. Just 1:1. You can specify your own offset for the default mapping the background, or leave it at 100000.
See https://pve.proxmox.com/wiki/Unprivileged_LXC_containers
NB: After adding the maps to the config and starting the container, the mapping mightn't take first go. Stop and restart the container and check again. I had to reboot a couple of times while testing.
Please check your results when applying, this code is in beta.