Deploying with Custom Roles

TripleO offers the option of deploying with a user-defined list of roles, each running a user defined list of services (where “role” means group of nodes, e.g “Controller”, and “service” refers to the individual services or configurations e.g “Nova API”).

See Deploying with Composable Services if you only wish to modify the default list of deployed services, or see below if you wish to modify the deployed roles.

Provided example roles

TripleO offers examples roles provided in openstack-tripleo-heat-templates. These roles can be listed using the tripleoclient by running:

openstack overcloud role list

With these provided roles, the user deploying the overcloud can generate a roles_data.yaml file that contains the roles they would like to use for the overcloud nodes. Additionally the user can manage their personal custom roles in a similar manor by storing the individual files in a directory and using the tripleoclient to generate their roles_data.yaml. For example, a user can execute the following to create a roles_data.yaml containing only the Controller and Compute roles:

openstack overcloud roles generate -o ~/roles_data.yaml Controller Compute

Deploying with custom roles

Each role is defined in the roles_data.yaml file. There is a sample file in /usr/share/openstack-tripleo-heat-templates, or the tripleo-heat-templates git repository.

The data in roles_data.yaml is used to perform templating with jinja2 such that arbitrary user-defined roles may be added, and the default roles may be modified or removed.

The steps to define your custom roles configuration are:

  1. Copy the default roles provided by tripleo-heat-templates:

    mkdir ~/roles cp /usr/share/openstack-tripleo-heat-templates/roles/* ~/roles

  2. Create a new role file with your custom role.

Additional details about the format for the roles file can be found in the README.rst in the roles/ directory from tripleo-heat-templates. The filename should match the name of the role. For example if adding a new role named Galera, the role file name should be Galera.yaml. The file should at least contain the following items:

  • name: Name of the role e.g “CustomController”, mandatory
  • ServicesDefault: List of services, optional, defaults to an empty list See the default roles_data.yaml or overcloud-resource-registry-puppet.j2.yaml for the list of supported services. Both files can be found in the top tripleo-heat-templates folder

Additional items like the ones below should be included as well:

  • CountDefault: Default number of nodes, defaults to zero
  • HostnameFormatDefault: Format string for hostname, optional
  • Description: A few sentences describing the role and information pertaining to the usage of the role.

The role file format is a basic yaml structure. The expectation is that there is a single role per file. See the roles README.rst for additional details. For example the following role might be used to deploy a pacemaker managed galera cluster:

- name: Galera
  HostnameFormatDefault: '%stackname%-galera-%index%'
  ServicesDefault:
    - OS::TripleO::Services::CACerts
    - OS::TripleO::Services::Timezone
    - OS::TripleO::Services::Ntp
    - OS::TripleO::Services::Snmp
    - OS::TripleO::Services::Kernel
    - OS::TripleO::Services::Pacemaker
    - OS::TripleO::Services::MySQL
    - OS::TripleO::Services::TripleoPackages
    - OS::TripleO::Services::TripleoFirewall
    - OS::TripleO::Services::SensuClient
    - OS::TripleO::Services::FluentdClient

Note

In the example above, if you wanted to deploy the Galera role on specific nodes you would either use predictable placement Controlling Node Placement and IP Assignment or add a custom parameter called OvercloudGaleraFlavor:

parameter_defaults:
  OvercloudGaleraFlavor: oooq_galera

Warning

When scaling your deployment out, you need as well set the role counts in the “parameter_defaults” section. The --control-scale and --compute-scale CLI args are hardcoded to the “Control” and “Compute” role names, so they’re in fact ignored when using custom roles.

  1. Create a roles_data.yaml file that contains the custom role in addition to the other roles that will be deployed. For example:

    openstack overcloud roles generate --roles-path ~/roles -o ~/my_roles_data.yaml Controller Compute Galera
    
  2. Pass the modified roles_data on deployment as follows:

    openstack overcloud deploy --templates -r ~/my_roles_data.yaml
    

Note

It is also possible to copy the entire tripleo-heat-templates tree, and modify the roles_data.yaml file in place, then deploy via –templates <copy of tht>

Warning

Note that in your custom roles you may not use any already predefined name So in practice you may not override the following roles: Controller, Compute, BlockStorage, SwiftStorage and CephStorage. You need to use different names instead.