libnss-pgsql2 binary package in Ubuntu Xenial amd64

 This module works as a replacement for the flat file databases /etc/passwd,
 /etc/group etc. It is a plugin to glibc's name service switch.
 .
 The module uses tables in a PostgreSQL database to store user, group, and
 shadow information. The module can be configured to use custom queries to
 retrieve it's information from a database. The module allows one to separate
 the configuration for shadow information from group and user information to
 restrict access to shadow information to privileged users (i.e. root or the
 shadow group).

Source package