I have an existing user database in Keycloak.
I want to build a Linux machine which logs in users according to the user database in Keycloak (username, password).
How can I accomplish this?
You would have to implement the following:
While it's not impossible it would be quite some development work.
The usual way of having centralized user management for Unix/Linux is to set up a LDAP server storing the relevant data. And then configure Keycloak to use this LDAP server for retrieving user data and check passwords.