Is there a way to pass a parameter to a puppet resource only if it's been set? For example, say I have a manifest that creates a new user, and I may or may not want to set the uid and gid manually. Best way I can think to do is like this:
class example (
$uid = undef,
$gid = undef,
$username = 'default'
) {
user { $username:
ensure => present,
# etc
}
if $uid != undef {
user { "uid-${username}":
name => $username,
uid => $uid,
require => User[$username]
}
}
if $gid != undef {
user { "gid-${username}":
name => $username,
gid => $gid,
require => User[$username]
}
}
}
But that is a lot of code just to determine whether or not to send the uid and/or gid. Is there a better way?
I think your example would fail to compile due to multiple declarations, because name on the user resource is what is being checked for uniqueness. That being said, there are a couple ways to make this slightly better in my opinion.
The first way involves attribute amending:
...
user { $username:
ensure => present,
# etc
}
if $uid != undef {
User[$username] { uid => $uid }
}
if $gid != undef {
User[$username] { gid => $gid }
}
The second involves setting attributes from a Hash:
class example (
Hash $id = {},
String $username = 'default'
) {
user { $username:
ensure => present,
* => $id,
# etc
}
}
and then either passing the additional parameters in via declaration:
class example { 'foo':
username => 'bar',
id => { uid => 1000, gid => 1000 }
}
or using automatic Hiera lookups similar to:
example::id:
uid: 1000
gid: 1000
Note that not specifying id in either case (declaration or Hiera) will still result in the correct and expected behavior of a user resource without uid or gid altered.
You can find both methods documented at https://docs.puppet.com/puppet/latest/reference/lang_resources_advanced.html, and you may even be able to figure out another method or two from that document.