Chapter 4. Heat parameters

Each heat template in the director template collection contains a parameters section. This section contains definitions for all parameters specific to a particular overcloud service. This includes the following:

  • overcloud.j2.yaml - Default base parameters
  • roles_data.yaml - Default parameters for composable roles
  • deployment/*.yaml - Default parameters for specific services

You can modify the values for these parameters using the following method:

  1. Create an environment file for your custom parameters.
  2. Include your custom parameters in the parameter_defaults section of the environment file.
  3. Include the environment file with the openstack overcloud deploy command.

4.1. Example 1: Configuring the time zone

The Heat template for setting the timezone (puppet/services/time/timezone.yaml) contains a TimeZone parameter. If you leave the TimeZone parameter blank, the overcloud sets the time to UTC as a default.

To obtain lists of timezones run the timedatectl list-timezones command. The following example command retrieves the timezones for Asia: 

$ sudo timedatectl list-timezones|grep "Asia"

After you identify your timezone, set the TimeZone parameter in an environment file. The following example environment file sets the value of TimeZone to Asia/Tokyo: 

parameter_defaults:
  TimeZone: 'Asia/Tokyo'

4.2. Example 2: Configuring RabbitMQ file descriptor limit

For certain configurations, you might need to increase the file descriptor limit for the RabbitMQ server. Use the deployment/rabbitmq/rabbitmq-container-puppet.yaml heat template to set a new limit in the RabbitFDLimit parameter. Add the following entry to an environment file: 

parameter_defaults:
  RabbitFDLimit: 65536

4.3. Example 3: Enabling and disabling parameters

You might need to initially set a parameter during a deployment, then disable the parameter for a future deployment operation, such as updates or scaling operations. For example, to include a custom RPM during the overcloud creation, include the following entry in an environment file: 

parameter_defaults:
  DeployArtifactURLs: ["http://www.example.com/myfile.rpm"]

To disable this parameter from a future deployment, it is not sufficient to remove the parameter. Instead, you must set the parameter to an empty value: 

parameter_defaults:
  DeployArtifactURLs: []

This ensures the parameter is no longer set for subsequent deployments operations.

4.4. Example 4: Role-based parameters

Use the [ROLE]Parameters parameters, replacing [ROLE] with a composable role, to set parameters for a specific role.

For example, director configures sshd on both Controller and Compute nodes. To set a different sshd parameters for Controller and Compute nodes, create an environment file that contains both the ControllerParameters and ComputeParameters parameter and set the sshd parameters for each specific role: 

parameter_defaults:
  ControllerParameters:
    BannerText: "This is a Controller node"
  ComputeParameters:
    BannerText: "This is a Compute node"

4.5. Identifying parameters that you want to modify

Red Hat OpenStack Platform director provides many parameters for configuration. In some cases, you might experience difficulty identifying a certain option that you want to configure, and the corresponding director parameter. If there is an option that you want to configure with director, use the following workflow to identify and map the option to a specific overcloud parameter:

  1. Identify the option that you want to configure. Make a note of the service that uses the option.

  2. Check the corresponding Puppet module for this option. The Puppet modules for Red Hat OpenStack Platform are located under /etc/puppet/modules on the director node. Each module corresponds to a particular service. For example, the keystone module corresponds to the OpenStack Identity (keystone).

    • If the Puppet module contains a variable that controls the chosen option, move to the next step.
    • If the Puppet module does not contain a variable that controls the chosen option, no hieradata exists for this option. If possible, you can set the option manually after the overcloud completes deployment.

  3. Check the core heat template collection for the Puppet variable in the form of hieradata. The templates in deployment/* usually correspond to the Puppet modules of the same services. For example, the deployment/keystone/keystone-container-puppet.yaml template provides hieradata to the keystone module.

    • If the heat template sets hieradata for the Puppet variable, the template should also disclose the director-based parameter that you can modify.
    • If the heat template does not set hieradata for the Puppet variable, use the configuration hooks to pass the hieradata using an environment file. See Section 5.4, “Puppet: Customizing hieradata for roles” for more information on customizing hieradata.

Procedure

  1. To change the notification format for OpenStack Identity (keystone), use the workflow and complete the following steps:

    1. Identify the OpenStack parameter that you want to configure (notification_format).

    2. Search the keystone Puppet module for the notification_format setting: 

      $ grep notification_format /etc/puppet/modules/keystone/manifests/*

      In this case, the keystone module manages this option using the keystone::notification_format variable.

    3. Search the keystone service template for this variable: 

      $ grep "keystone::notification_format" /usr/share/openstack-tripleo-heat-templates/deployment/keystone/keystone-container-puppet.yaml

      The output shows that director uses the KeystoneNotificationFormat parameter to set the keystone::notification_format hieradata.

The following table shows the eventual mapping:

Director parameterPuppet hieradataOpenStack Identity (keystone) option

KeystoneNotificationFormat

keystone::notification_format

notification_format

You set the KeystoneNotificationFormat in an overcloud environment file, which then sets the notification_format option in the keystone.conf file during the overcloud configuration.