Start writing modules for Windows

Follow these steps to create a module with a single class called critical_policy that manages a collection of important settings and options in your Windows registry, most notably the legal caption and text users see before the login screen.

1. On the Puppet master, make sure you're still in the modules directory, cd /etc/puppetlabs/code/environments/production/modules, and then run mkdir -p critical_policy/manifests to create the new module directory and its manifests directory.
2. Use your text editor to create and open the critical_policy/manifests/init.pp file.
3. Edit the init.pp file so it contains the following Puppet code, and then save it and exit the editor:

   class critical_policy {
   
     registry::value { 'Legal notice caption':
       key   => 'HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System',
       value => 'legalnoticecaption',
       data  => 'Legal Notice',
       }
   
     registry::value { 'Legal notice text':
       key   => 'HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System',
       value => 'legalnoticetext',
       data  => 'Login constitutes acceptance of the End User Agreement',
       }
     }

Puppet recognizes when you create a custom class, and it can be added to the console and assigned to your Windows nodes.

1. In the console, click Classification, and select the node group you want to add your module to (for example, Windows_example).
2. On the Configuration tab, in the Add new class field, enter critical_policy.

   You might need to wait a moment or two for the class to show up in the list. You can also click Refresh.

3. Click Add class, and commit changes.

Check to make sure your module does what you expect it to: display the legal caption and text before you log in.

1. On the Windows agent node, manually set the data values of legalnoticecaption and legalnoticetext to some other values. For example, set legalnoticecaption to “Larry’s Computer” and set legalnoticetext to “This is Larry’s computer.”
2. On the Windows agent node, refresh the registry and note that the values of legalnoticecaption and legalnoticetext have been returned to the values specified in your critical_policy manifest.
3. Reboot your Windows machine to see the legal caption and text before you log in again. You have created a new class from scratch and used it to manage registry settings on your Windows server.

Many users create a "site" module for a type of machine.

1. On the Puppet master, create the /etc/puppetlabs/code/environments/production/modules/site/manifests/basic.pp file by running mkdir -p site/manifests. Then, edit it to contain the following:

   class site::basic {
     if $osfamily == 'windows' {
       include critical_policy
     }
     else {
       include motd
       include core_permissions
     }
   }

2. Run puppet agent -t to ensure site::basic is created. This class declares other classes with the include function.
   Note: The "if" conditional sets different classes for different operating systems using the $osfamily fact. In this example, if an agent node is not a Windows agent, Puppet applies the motd and core_permissions classes. For more information about declaring classes, see the modules and classes chapters of Learning Puppet.
3. In the console, remove all of the previous example classes from your nodes and groups (for example, wsus_client and critical_policy). Be sure to leave the pe_* classes in place.
4. Add the site::basic class to the console with Add new class.
5. Assign the site::basic class to the windows_example group. Your nodes are now receiving the same configurations as before, but with a simplified interface in the console. Instead of deciding which classes a new node should receive, you can decide what type of node it is and take advantage of decisions you made earlier.