10.2. Customizing Overcloud Pre-Configuration

The Overcloud uses Puppet for core configuration of OpenStack components. The director provides a set of resources to provide custom configuration after the first boot completes and before the core configuration begins. These resources include:
OS::TripleO::ControllerExtraConfigPre
Additional configuration applied to Controller nodes before the core Puppet configuration.
OS::TripleO::ComputeExtraConfigPre
Additional configuration applied to Compute nodes before the core Puppet configuration.
OS::TripleO::CephStorageExtraConfigPre
Additional configuration applied to CephStorage nodes before the core Puppet configuration.
OS::TripleO::NodeExtraConfig
Additional configuration applied to all nodes roles before the core Puppet configuration.
In this example, we first create a basic Heat template (/home/stack/templates/nameserver.yaml) that runs a script to append each node's resolv.conf with a variable nameserver. 
heat_template_version: 2014-10-16

description: >
  Extra hostname configuration

parameters:
  server:
    type: string
  nameserver_ip:
    type: string
  DeployIdentifier:
    type: string

resources:
  ExtraPreConfig:
    type: OS::Heat::SoftwareConfig
    properties:
      group: script
      config:
        str_replace:
          template: |
            #!/bin/sh
            echo "nameserver _NAMESERVER_IP_" >> /etc/resolv.conf
          params:
            _NAMESERVER_IP_: {get_param: nameserver_ip}

  ExtraPreDeployment:
    type: OS::Heat::SoftwareDeployment
    properties:
      config: {get_resource: ExtraPreConfig}
      server: {get_param: server}
      actions: ['CREATE','UPDATE']
      input_values:
        deploy_identifier: {get_param: DeployIdentifier}

outputs:
  deploy_stdout:
    description: Deployment reference, used to trigger pre-deploy on changes
    value: {get_attr: [ExtraPreDeployment, deploy_stdout]}
In this example, the `resources` section contains the following:
ExtraPreConfig
This defines a software configuration. In this example, we define a Bash script and Heat replaces _NAMESERVER_IP_ with the value stored in the nameserver_ip parameter.
ExtraPreDeployments
This executes a software configuration, which is the software configuration from the ExtraPreConfig resource. Note the following:
  • The server parameter is provided by the parent template and is mandatory in templates for this hook.
  • input_values contains a parameter called deploy_identifier, which stores the DeployIdentifier from the parent template. This parameter provides a timestamp to the resource for each deployment update. This ensures the resource reapplies on subsequent overcloud updates.
Next, create an environment file (/home/stack/templates/pre_config.yaml) that registers our Heat template as the OS::TripleO::NodeExtraConfig resource type. 
resource_registry:
  OS::TripleO::NodeExtraConfig: /home/stack/templates/nameserver.yaml

parameter_defaults:
  nameserver_ip: 192.168.1.1
To add the configuration, add the environment file to the stack when creating or updating the Overcloud. For example: 
$ openstack overcloud deploy --templates -e /home/stack/templates/pre_config.yaml
This adds the configuration to all nodes before the core configuration begins on either the initial Overcloud creation or subsequent updates.

Important

You can only register these resources to only one Heat template each. Subsequent usage overrides the Heat template to use per resource.