Defining puppet class ordering when if statement exists

Question

I have a Puppet class which, among other things, sets up a whole bunch of Debian repositories, performs an apt-get update and then installs a few packages.

The ordering must be strictly as follows:

setup apt sources
apt-get update
install application packages

To define the ordering, I have used the following chaining after declaring all of my resources:

File['/etc/apt/apt.conf','/etc/apt/sources.list'] ->
Exec['apt-get update'] ->
Class['vim','sudo', ..., ..., ]

However, here is the issue:

If I set vim to install only if the host is a virtual machine, and the host I am performing the Puppet run on is physical, the run will fail. I assume this is because it is attempting to run Class['vim'] as per my chaining but cannot find the class declaration due to the contents of the if statement not being parsed.

Here is the code:

if $::is_virtual == 'true' {
    class {'vim': 
      set_default => true,
  }
}

I can work around this by adding a "requires => Exec['apt-get update']" to my vim resource declaration and removing from my chain, but this feels a bit hacky. Here is what my class declaration looks like once I do this:

if $::is_virtual == 'true' {
    class {'vim':
      requires => Exec['apt-get update'],
      set_default => true,
  }
}

Does anybody have any other methods of dealing with such ordering issues? Is there anyway I can deal with ordering classes held within conditional statements which may or may not be triggered via chaining? Any advice is appreciated.

Writing dependency chains like this is hacky exactly because of issues like the one you're dealing with now. It's much safer to handle dependencies by require/notify/subscribe. — Mateusz M.

Felix Frank Felix Frank · Accepted Answer · 2015-07-27T12:58:56

Your approach using require is sound. If you really have to stick to the chaining operator, you can wrap the if block in yet another class.

class site::vim {
    if $::is_virtual == 'true' { ... }
}

Then include and chain Class[site::vim], which will honor the is_virtual value on its own.

Defining puppet class ordering when if statement exists

1 Answers