10.5. Applying Custom Puppet Configuration

In certain circumstances, you might need to install and configure some additional components to your Overcloud nodes. You can achieve this with a custom Puppet manifest that applies to nodes on after the main configuration completes. As a basic example, you might aim to install motd to each node. The process for accomplishing is to first create a Heat template (/home/stack/templates/custom_puppet_config.yaml) that launches Puppet configuration. 
heat_template_version: 2014-10-16

description: >
  Run Puppet extra configuration to set new MOTD

parameters:
  servers:
    type: json

resources:
  ExtraPuppetConfig:
    type: OS::Heat::SoftwareConfig
    properties:
      config: {get_file: motd.pp}
      group: puppet
      options:
        enable_hiera: True
        enable_facter: False

  ExtraPuppetDeployments:
    type: OS::Heat::SoftwareDeployments
    properties:
      config: {get_resource: ExtraPuppetConfig}
      servers: {get_param: servers}
This includes the /home/stack/templates/motd.pp within the template and passes it to nodes for configuration. The motd.pp file itself contains our Puppet classes to install and configure motd.
Next, create an environment file (/home/stack/templates/puppet_post_config.yaml) that registers our Heat template as the OS::TripleO::NodeExtraConfigPost: resource type. 
resource_registry:
  OS::TripleO::NodeExtraConfigPost: /home/stack/templates/custom_puppet_config.yaml
And finally include this environment file when creating or updating the Overcloud stack: 
$ openstack overcloud deploy --templates -e /home/stack/templates/puppet_post_config.yaml
This applies the configuration from motd.pp to all nodes in the Overcloud.