Node scope variables

[Robin Y.]

Greetings,

I could use some clarity on node scope, class scope, and best practices.  I have the following:

# Node definition

if $hostname == 'mynode-dev' {

    $app_version = '1.0'

    include robin_dev

}

# Class definition 

class robin_dev {

    if $app_version == undef {

        $app_version = '0.5'

    }

    include robin_dev::install

}

class robin_dev::install {

    package {

        "app_name":                       ensure => $robin_dev::app_version;

    }

}

My intent is to set $app_version within my node definition.  If $app_version is not set there, I 'd like it to default to a version that is set within class robin_dev itself, which is 0.5 in the above example.

While the above example works as I just described, i'm not understanding how $robin_dev::app_version referenced in class robin_dev::install returns "1.0" when I its assigned in the node definition.  I initially assumed that class robin_dev would need to re-assign the variable within the class itself like this:

# Class definition 

class robin_dev {

    if $app_version == undef {

        $version = '0.5'

    } else {

                    $version = $app_version

    include robin_dev::install

}

 class robin_dev::install {

    package {

        "app_name":                       ensure => $robin_dev::version;

    }

}

 Any insights would be appreciated.  Thank you.

[Craig Dunn]

You seem to have a couple of misunderstandings here - Firstly what you call a node definition isn't a node definition, that would look something like

node 'mynode-dev' {
include robin_dev
}

Secondly, you want to make your robin_dev class parameterized to achieve what you want, e.g.:

class robin_dev (
$app_version = '0.5'
) {
include robin_dev::install
}

This parameter can now be overridden when you declare the class in the node definition….

class { 'robin_dev':
app_version => '1.0',
}

Or even better, use Hiera and override it there and include the class without parameters

eg: hosts/mynode-dev.yaml
---
robin_dev::app_version: 1.0

Regards
Craig

--
Enviatics | Automation and Configuration Management
http://www.enviatics.com | @Enviatics
Puppet Training Courses http://www.enviatics.com/training/

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