Ask HN: How do you deal with users on your machines?

Hey, folks. Most of the software I build gets deployed to Actual Linux Boxes -- either virtual or metal -- and I have yet to find a good solution for user management on those machines.

These boxes nominally live in the cloud, and not in a datacenter that I control.

I'm looking for something that can automate the process of adding and removing shell users on a large number of boxes, including access to databases and such.

What does the HN community use to deal with this?