I dont use ubuntu extensively, but a quick google says this might
help
https://marc.wäckerlin.ch/computer/blog/ssh_and_ldap
Thanks! Do you know is it possible to mix public keys in local
filesystem and in LDAP? Does it search from both? Just thinking about
situation if LDAP is down for some reason, it would be good to have a
local fallback user in servers.
-Mr Vesa Alho