I would like to add via puppet a system user to Debian boxes.
The user is:
user { 'puppet':
ensure => 'present',
comment => 'puppetserver daemon',
gid => '109',
groups => ['www-data'],
home => '/opt/puppetlabs/server/data/puppetserver',
shell => '/bin/false',
uid => '107',
}
(uid and gid taken from user created by the package puppetserver).
Can I be confident uid 107 is not already taken on some boxes by other services? Are there safe uids on Debian? How does it work the system users' uid allocation in Debian?
If you google for "Debian user id" you will find the Debian Policy Manual which describes different ranges in the uid space.
UIDs 100-999 are used for packages, so collisions are possible and you should not use that. Instead put your site-local schema into the 1000-59999 range. I would also suggest not to start at 1000 and use 1007, because some system may have eight "real" user accounts. Start your own range of Puppet-generated and managed uids at some high number, e.g. at 50000.