In OpenStack, certain user IDs are reserved and used to run specific OpenStack services and own specific OpenStack files. These users are set up according to the distribution packages. The following table gives an overview. Some OpenStack packages generate and assign user IDs automatically during package installation. In these cases, the user ID value is not important. The existence of the user ID is what matters.

Reserved user IDs

Name	Description	ID
ceilometer	OpenStack Ceilometer Daemons	166	Assigned during package installation
cinder	OpenStack Cinder Daemons	165	Assigned during package installation
glance	OpenStack Glance Daemons	161	Assigned during package installation
heat	OpenStack Heat Daemons	187	Assigned during package installation
keystone	OpenStack Keystone Daemons	163	Assigned during package installation
neutron	OpenStack Neutron Daemons	164	Assigned during package installation
nova	OpenStack Nova Daemons	162	96	Assigned during package installation
swift	OpenStack Swift Daemons	160	Assigned during package installation
trove	OpenStack Trove Daemons	Assigned during package installation

Each user belongs to a user group with the same name as the user.