On certain servers I want IPA authentication but the local user/group database. With sssd
1.14, I could specify pam as the only service and put files in /etc/nsswitch.conf. With
sssd 1.15, I get extra groups with that setting. I had to set id_provider=none, which is
undocumented. I'd be happy to see id_provider=files for this situation, though
id_provider=none with nsswitch seems to do what I need.
I do have a user with a static password, for cases where services are down. That can be
done in pam, by having pam_unix as well as pam_sss. It would be interesting to have sssd
handle this kind of mixed case, but it seems like this is what pam is for.