Using Fuel settings¶

Fuel uses a special method to pass settings from Nailgun to Puppet manifests:

• Before the deployment process begins, Astute uploads all settings to the /etc/astute.yaml files that are located on each node.
• When Puppet is run, Facter reads the contents of all these /etc/astute.yaml files and creates a single file called $astute_settings_yaml.
• The parseyaml function (at the beginning of the site.pp file) then parses these settings and creates a rich data structure called $fuel_settings. All of the settings used during node deployment are stored there and can be used anywhere in Puppet code.

For example, single top level variables are available as $::fuel_settings[‘debug’]. More complex structures are also available as values of $::fuel_settings hash keys and can be accessed like normal hashes and arrays. Many aliases and generated values are provided to help you retrieve values easily. You can create a variable from any hash key in $fuel_settings and work with this variable within your local scope or from other classes, using fully qualified paths:

$debug = $::fuel_settings['debug']

Some variables and structures are generated from the settings hash by filtering and transformation functions. For example the $node structure only contains settings of the current node, filtered from the has of all nodes. It can be accessed as:

$node = filter_nodes($nodes_hash, 'name', $::hostname)

If you are going to use your module inside the Fuel Library and need some settings, you can get them from this $::fuel_settings structure. Most variables related to network and OpenStack services configuration are already available there and you can use them as they are. If your modules require some additional or custom settings, you must either use Custom Attributes by editing the JSON files before deployment, or, if you are integrating your project with the Fuel Library, you can contact the Fuel UI developers and ask them to add your configuration options to the Fuel setting panel.

After you have defined all classes you need inside your module, you can add this module’s declaration into the Fuel manifests such as cluster_simple.pp and cluster_ha.pp located inside the osnailyfacter/manifests folder or, if your additions are related to another class, can add them into that class.

Example module¶

To demonstrate how to add a new module to the Fuel Library, let us add a simple class that changes the terminal color of Red Hat based systems. Our module is named profile and has only one class.:

profile
profile/manifests
profile/manifests/init.pp
profile/files
profile/files/colorcmd.sh

init.pp could have a class definition such as::

class profile {
  if $::osfamily == 'RedHat' {
    file { 'colorcmd.sh' :
      ensure   => present,
      owner    => 'root',
      group    => 'root',
      mode     => '0644',
      path     => "/etc/profile.d/colorcmd.sh",
      source   => 'puppet:///modules/profile/colorcmd.sh',
    }
  }
}

This class downloads the colorcmd.sh file and places it in the defined location when the class is run on a Red Hat or CentOS system. The profile module can be added to Fuel modules by uploading its folder to /etc/puppet/modules on the Fuel Master node.

Now we need to declare this module somewhere inside the Fuel manifests. Since this module should be run on every server, we can use our main site.pp manifest found inside the osnailyfacter/examples folder. On the deployed master node, this file will be copied to /etc/puppet/manifests and used to deploy Fuel on all other nodes. The only thing we need to do here is to add the include profile to the end of the /etc/puppet/manifests/site.pp file on the already deployed master node and to the osnailyfacter/examples/site.pp file inside the Fuel repository.

Declaring a class outside of a node block forces this class to be included everywhere. If you want to include your module only on some nodes, you can add its declaration to the blocks associated with the role that is running on those nodes inside the cluster_simple and cluster_ha classes.

You can add some additional logic to allow this module to be disabled, either from the Fuel UI or by passing Customer Attributes to the Fuel configuration.:

if $::fuel_settings['enable_profile'] {
  include 'profile'
}

This block uses the enable_profile variable to enable or disable inclusion of the profile module. The variable should be passed from Nailgun and saved to the /etc/astute.yaml files on managed nodes. You can do this either by downloading the settings files and manually editing them before deployment or by asking the Fuel UI developers to include additional options in the settings panel.