openstack/tripleo-docs
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c04ac6df923f6fc50342ef32e9da39875901e447
tripleo-docs/doc/source/install/advanced_deployment/composable_services.rst
Steven Hardy b5cec752cb Clarify composable services docs 
This references CustomController, but in fact composable services and
override of the default service list works fine for the built in
default roles, so clarify this by just referencing the ControllerServices.

Change-Id: I5aa8e5542f19d9a04e0d68f4bb543e68f5801391
2017-11-15 16:54:00 +00:00

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Deploying with Composable Services

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

Deploying with custom service lists

Each role to be used in the deployment is defined in a roles_data.yaml file. There is a sample file in /usr/share/openstack-tripleo-heat-templates, or the tripleo-heat-templates git repository. Additional example roles are located in the /usr/share/openstack-tripleo-heat-templates/roles directory and can be used to create a custom roles_data.yaml file. See custom_roles for additional usage details.

The data in roles_data.yaml is used to set the defaults for per-role parameters e.g ControllerServices. These defaults can be overridden via environment files, e.g:

cat > keystone_only_params.yaml << EOF

parameter_defaults:
  ControllerServices:
    - OS::TripleO::Services::Keystone
    - OS::TripleO::Services::RabbitMQ
    - OS::TripleO::Services::HAproxy
    - OS::TripleO::Services::MySQL
  ComputeCount: 0
EOF

The example above overrides the default list of services, and instead deploys Keystone and the services it requires. It also sets the ComputeCount to zero to enable a minimal "keystone only" deployment on a single node.

You can then pass the environment file on deployment as follows:

openstack overcloud deploy -e keystone_only_params.yaml

The same approach can be used for any role.

Warning

While considerable flexibilty is available regarding service placement with these interfaces, the flexible placement of pacemaker managed services is only available since the Ocata release.

Warning

In general moving control-plane services to the Compute role is not recommended, as the compute nodes require a different upgrade lifecycle and thus control-plane services on this role may present problems during major upgrades between releases.