Puppet Install specific version of package depending on application version - ruby

Question

I have a module which installs my Application.
To install system packages i'm using virtual resource:
#package {[
'unzip',
'wget',
'htop',
'xorg-x11-server-Xvfb']:
ensure => installed,
}
define myapp1_packages {
realize(
Package['unzip'],
Package['fontconfig'],
Package['libfreetype.so.6'])
}
#myapp1_packages{ 'myapp1_packages': }
Then I use realize in my manifest to install the above packages:
realize(myapp1_packages['myapp1_packages'])
But for each version of my application I also need appropriate versions of system packages.
I need something like that:
if $app_version == '1.0' {
"install unzip-1xx"
"install fontconfig-1-xx"
"install libfreetype.so.6-1-x-xx"
elseif $app_version == '2.0'
"install unzip-2xx"
"install fontconfig-2-xx"
"install libfreetype.so.6-2-x-xx"
What is most elegant way to do this? And is it possible to keep virtual resources in that case? I'm looking to use ensure_packages but i worried about resource duplication. Thanks for the help!

Answer 1

The best thing to do here is to make $app_version a parameter for your module: https://docs.puppet.com/puppet/4.10/lang_classes.html#class-parameters-and-variables. Note an example from the documentation here: https://docs.puppet.com/puppet/4.10/lang_classes.html#appendix-smart-parameter-defaults.
For your situation, the class would look like:
myclass($app_version = 'default version') {
if $app_version == '1.0' {
#package { 'unzip': ensure => '1xx' }
#package { 'fontconfig': ensure => '1-xx' }
#package { 'libfreetype': ensure => '6-1-xx' }
}
elsif $app_version == '2.0' {
#package { 'unzip': ensure => '2xx' }
#package { 'fontconfig': ensure => '2-xx' }
#package { 'libfreetype': ensure => '6-2-xx' }
}
}
thus also allowing you to retain your virtual resources.
You can then pass parameters to this class by declaring it like:
class { 'myclass': app_version => '2.0' }
or using automatic data bindings with hieradata:
# puppet manifest
include myclass
# hieradata
myclass::app_version: 2.0
Your collector elsewhere will then realize the correct versions for your packages.