Chapter 3. Parameters

Each Heat template in the director’s template collection contains a parameters section. This section defines 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.

The next few sections contain examples to demonstrate how to configure specific parameters for services in the deployment directory.

3.1. 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'

3.2. Example 2: Enabling Networking Distributed Virtual Routing (DVR)

DVR is enabled by default in new ML2/OVN deployments and disabled by default in new ML2/OVS deployments. The Heat template for the OpenStack Networking (neutron) API (deployment/neutron/neutron-api-container-puppet.yaml) contains a parameter to enable and disable Distributed Virtual Routing (DVR). To disable DVR, use the following in an environment file: 

parameter_defaults:
  NeutronEnableDVR: false

3.3. Example 3: Configuring RabbitMQ File Descriptor Limit

For certain configurations, you might need to increase the file descriptor limit for the RabbitMQ server. The deployment/rabbitmq/rabbitmq-container-puppet.yaml Heat template allows you to set the RabbitFDLimit parameter to the limit you require. Add the following to an environment file: 

parameter_defaults:
  RabbitFDLimit: 65536

3.4. Example 4: 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: 

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

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

parameter_defaults:
  DeployArtifactURLs: []

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

3.5. Example 5: 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 logrotate on both Controller and Compute nodes. To set a different different logrotate parameters for Controller and Compute nodes, create an environment file that contains both the ‘ControllerParameters’ and ‘ComputeParameters’ parameter and set the logrotate parameter for each specific role: 

parameter_defaults:
  ControllerParameters:
    LogrotateMaxsize: 10M
    LogrotatePurgeAfterDays: 30
  ComputeParameters:
    LogrotateMaxsize: 20M
    LogrotatePurgeAfterDays: 15

3.6. Identifying Parameters to Modify

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

  1. Identify the option you aim 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 director’s 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 to 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 4.5, “Puppet: Customizing Hieradata for Roles” for more information on customizing hieradata.

Workflow Example

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

  1. Identify the OpenStack parameter to configure (notification_format).

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

    $ 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. For example: 

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

    The output shows the director using 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’s environment file which in turn sets the notification_format option in the keystone.conf file during the overcloud’s configuration.