tripleo-docs/doc/source/advanced_deployment/composable_services.rst
Steven Hardy 1fb9641e6d Add docs for composable services/roles
This adds some basic docs explaining how to use composable services
and custom roles.

Change-Id: I22b84cc22db7aa60265a13a3cb26e28a98190105
2017-02-20 23:21:07 +01:00

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2.0 KiB
ReStructuredText

.. _composable_services:
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 defines a default list of services, which can be viewed in the
`roles_data.yaml` file (see `/usr/share/openstack-tripleo-heat-templates`, or
the tripleo-heat-templates_ git repository.)
The data in `roles_data.yaml` is used to set the defaults for per-role parameters
e.g `CustomControllerServices`. These defaults can be overridden via environment
files, e.g::
cat > keystone_only_params.yaml << EOF
parameter_defaults:
CustomControllerServices:
- OS::TripleO::Services::Keystone
- OS::TripleO::Services::RabbitMQ
- OS::TripleO::Services::HAproxy
- OS::TripleO::Services::MySQL
ComputeCount: 0
OvercloudCustomControllerFlavor: customcontroller
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.
.. _tripleo-heat-templates: https://git.openstack.org/openstack/tripleo-heat-templates