Puppet - test if a package already defined?

Question

I\'m writing some puppet modules and have a package defined in two modules hence get the following error:

err: Could not retrieve catalog from remote server: Err         


        

Answer 1

You are missing Package[] inside defined(). The correct way to do it:

if ! defined(Package['gnome-session-fallback']) {
    package { 'gnome-session-fallback':
        ensure => installed,
    }
}

Answer 2

The cleanest way to do this is to use the ensure_resource function from puppetlabs-stdlib:

ensure_resource('package', 'gnome-session-fallback', {'ensure' => 'present'})

Answer 3

To answer my own question about what the "proper" approach is : This issue is discussed at https://groups.google.com/forum/?fromgroups=#!topic/puppet-users/julAujaVsVk and jcbollenger offers what looks like a "best-practice" solution - resources which are defined multiple times should be moved into their own module and included into the classes on which they depend. I applied this and solved my problem.

This doesn't actually answer why "if !defined" fails however...

Answer 4

One cleaner way (among multiple ways) is to create a virtual package resource and then realize it. You can realize the same virtual package multiple times without error.

@package { 'gnome-session-fallback':
    ensure => installed,
}

And then where you need it:

realize( Package[ 'gnome-session-fallback' ] )