Class composition + parameterization

[Joaquin Menchaca]

I am sleuthing for this and haven't found anything obvious yet.

I have an init.pp that looks like this

class dk_oracle_java (

  $docroot     = $::dk_oracle_java::params::docroot,

  Optional[String] $local_repo  = $::dk_oracle_java::params::local_repo,

  $version     = $::dk_oracle_java::params::version,

  $javas       = $::dk_oracle_java::params::javas,

) inherits ::dk_oracle_java::params {

    include ::dk_oracle_java::install

}

And I want to access the $version in my install.pp, but I am not sure how to do this.

class dk_oracle_java::install {

  package { 'oracle-java8-installer':

    ensure => $version,

  }

}

How can I get this to work, or what is the best practice.  Can the install.pp access parameters from the base class, $::version?  Or does this need to be passed downward?

[Joaquin Menchaca]

I spotted it, seems obvious now:

class dk_oracle_java::install inherits dk_oracle_java {

[a...@example42.com]

Actually you don't have to inherit, you can (and should) just have something like:

class dk_oracle_java::install {
  include dk_oracle_java

  package { 'oracle-java8-installer':

    ensure => $::dk_oracle_java::version,

  }

}

The above include is not necessary if you are already incuding the dk_oracle_java class somewhere else, just be sure that the class is included before you refer to its variables.
The only currently acceptable reasons to use class inheritance is:
- when using the params patterm (main class of a module inheriting the params one), which is actully now totally unnecessary and can be replaced by data in module.
- when for whatever reason you have to change some parameters of a resource already declared in the inherited class, and also for this case you can have other workarounds.

Anyway inheritance still works, and so if it works for you it's ok.

[Thomas Müller]

Am Montag, 7. Mai 2018 09:21:20 UTC+2 schrieb a...@example42.com:

Actually you don't have to inherit, you can (and should) just have something like:

class dk_oracle_java::install {
  include dk_oracle_java

  package { 'oracle-java8-installer':

    ensure => $::dk_oracle_java::version,

  }

}

 

The above include is not necessary if you are already incuding the dk_oracle_java class somewhere else, just be sure that the class is included before you refer to its variables.

I personally consider the *::install, *::config, *::service classes as private and they should not include the parent class - they should be contained from the main class. Outside of the module only the main class should be included. The *::install and other classes should fail if included from outside (maybe with help of: https://github.com/puppetlabs/puppetlabs-stdlib#assert_private).

And if not yet using: I would recommend you the PDK (https://puppet.com/docs/pdk/1.x/pdk.html) which will also create basic test classes for you.

- Thomas