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Merge "[DOCS] Applies edits to the OSA install guide appendix C"

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doc/source/install-guide/app-custom-layouts.rst
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@ -2,87 +2,86 @@
Appendix C: Customizing host and service layouts
==================================================
Understanding the default layout
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The default layout of containers and services in OpenStack-Ansible (OSA) is
determined by the ``/etc/openstack_deploy/openstack_user_config.yml`` file and
the contents of both the ``/etc/openstack_deploy/conf.d/`` and
``/etc/openstack_deploy/env.d/`` directories. You use these sources to define
the *group* mappings that the playbooks use to target hosts and containers for
roles used in the deploy.
The default layout of containers and services in OpenStack-Ansible is driven
by the ``/etc/openstack_deploy/openstack_user_config.yml`` file and the
contents of both the ``/etc/openstack_deploy/conf.d/`` and
``/etc/openstack_deploy/env.d/`` directories. Use these sources to define the
group mappings used by the playbooks to target hosts and containers for roles
used in the deploy.
* You define host groups, which gather the target hosts into *inventory
groups*, through the ``/etc/openstack_deploy/openstack_user_config.yml``
file and the contents of the ``/etc/openstack_deploy/conf.d/`` directory.
Conceptually, these can be thought of as mapping from two directions. You
define host groups, which gather the target hosts into inventory groups,
through the ``/etc/openstack_deploy/openstack_user_config.yml`` file and the
contents of the ``/etc/openstack_deploy/conf.d/`` directory. You define
container groups, which can map from the service components to be deployed up
to host groups, through files in the ``/etc/openstack_deploy/env.d/``
directory.
* You define *container groups*, which can map from the service components
to be deployed up to host groups, through files in the
``/etc/openstack_deploy/env.d/`` directory.
To customize the layout of components for your deployment, modify the
host groups and container groups appropriately to represent the layout you
desire before running the installation playbooks.
To customize the layout of the components for your deployment, modify the
host groups and container groups appropriately before running the installation
playbooks.
Understanding host groups
-------------------------
~~~~~~~~~~~~~~~~~~~~~~~~~
As part of initial configuration, each target host appears in either the
As part of the initial configuration, each target host appears either in the
``/etc/openstack_deploy/openstack_user_config.yml`` file or in files within
the ``/etc/openstack_deploy/conf.d/`` directory. We use a format for files in
``conf.d/`` which is identical to the syntax used in the
``openstack_user_config.yml`` file. These hosts are listed under one or more
the ``/etc/openstack_deploy/conf.d/`` directory. The format used for files in
the ``conf.d/`` directory is identical to the syntax used in the
``openstack_user_config.yml`` file.
In these files, the target hosts are listed under one or more
headings, such as ``shared-infra_hosts`` or ``storage_hosts``, which serve as
Ansible group mappings. We treat these groupings as mappings to the physical
Ansible group mappings. These groups map to the physical
hosts.
The example file ``haproxy.yml.example`` in the ``conf.d/`` directory provides
The ``haproxy.yml.example`` file in the ``conf.d/`` directory provides
a simple example of defining a host group (``haproxy_hosts``) with two hosts
(``infra1`` and ``infra2``).
A more complex example file is ``swift.yml.example``. Here, we
specify host variables for a target host using the ``container_vars`` key.
The ``swift.yml.example`` file provides a more complex example. Here, host
variables for a target host are specified by using the ``container_vars`` key.
OpenStack-Ansible applies all entries under this key as host-specific
variables to any component containers on the specific host.
.. note::
We recommend new inventory groups, particularly for new
services, to be defined using a new file in the ``conf.d/`` directory in
order to manage file size.
To manage file size, we recommend that you define new inventory groups,
particularly for new services, by using a new file in the
``conf.d/`` directory.
Understanding container groups
------------------------------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Additional group mappings can be found within files in the
``/etc/openstack_deploy/env.d/`` directory. These groupings are treated as
Additional group mappings are located within files in the
``/etc/openstack_deploy/env.d/`` directory. These groups are treated as
virtual mappings from the host groups (described above) onto the container
groups which define where each service deploys. By reviewing files within the
groups, that define where each service deploys. By reviewing files within the
``env.d/`` directory, you can begin to see the nesting of groups represented
in the default layout.
We begin our review with ``shared-infra.yml``. In this file we define a
new container group (``shared-infra_containers``) as a subset of the
``all_containers`` group. This new container group is mapped to a new
(``shared-infra_hosts``) host group. This means you deploy all service
components under the new (``shared-infra_containers``) container group to each
target host in the host group (``shared-infra_hosts``).
For example, the ``shared-infra.yml`` file defines a container group,
``shared- infra_containers``, as a subset of the all_containers inventory
group. The ``shared- infra_containers`` container group is mapped to the
``shared-infra_hosts`` host group. All of the service components in the
``shared-infra_containers`` container group are deployed to each target host
in the ``shared-infra_hosts host`` group.
Within a ``physical_skel`` segment, the OpenStack-Ansible dynamic inventory
Within a ``physical_skel`` section, the OpenStack-Ansible dynamic inventory
expects to find a pair of keys. The first key maps to items in the
``container_skel`` and the second key maps to the target host groups
(described above) which are responsible for hosting the service component.
``container_skel`` section, and the second key maps to the target host groups
(described above) that are responsible for hosting the service component.
Next, we review ``memcache.yml``. Here, we define the new group
``memcache_container``. In this case we identify the new group as a
subset of the ``shared-infra_containers`` group, which is itself a subset of
To continue the example, the ``memcache.yml``file defines the
``memcache_container`` container group. This group is a subset of the
``shared-infra_containers`` group, which is itself a subset of
the ``all_containers`` inventory group.
.. note::
The ``all_containers`` group is automatically defined by OpenStack-Ansible.
Any service component managed by OpenStack-Ansible maps to a subset of the
``all_containers`` inventory group, whether directly or indirectly through
``all_containers`` inventory group, directly or indirectly through
another intermediate container group.
The default layout does not rely exclusively on groups being subsets of other
@ -90,7 +89,7 @@ groups. The ``memcache`` component group is part of the ``memcache_container``
group, as well as the ``memcache_all`` group and also contains a ``memcached``
component group. If you review the ``playbooks/memcached-install.yml``
playbook, you see that the playbook applies to hosts in the ``memcached``
group. Other services may have more complex deployment needs. They define and
group. Other services might have more complex deployment needs. They define and
consume inventory container groups differently. Mapping components to several
groups in this way allows flexible targeting of roles and tasks.
@ -101,92 +100,94 @@ Deploying directly on hosts
---------------------------
To deploy a component directly on the host instead of within a container, set
the ``is_metal`` property to ``true`` for the container group under the
``container_skel`` in the appropriate file.
the ``is_metal`` property to ``true`` for the container group in the
``container_skel`` section in the appropriate file.
The use of ``container_vars`` and mapping from container groups to host groups
is the same for a service deployed directly onto the host.
.. note::
The ``cinder-volume`` component is also deployed directly on the host by
The ``cinder-volume`` component is deployed directly on the host by
default. See the ``env.d/cinder.yml`` file for this example.
Omit a service or component from the deployment
-----------------------------------------------
To omit a component from a deployment, several options exist:
To omit a component from a deployment, you can use one of several options:
- Remove the ``physical_skel`` link between the container group and
the host group. The simplest way to do this is to delete the related
file located in the ``env.d/`` directory.
- Do not run the playbook which installs the component.
Unless you specify the component to run directly on a host using
``is_metal``, a container creates for this component.
- Adjust the `affinity`_ to 0 for the host group. Unless you
specify the component to run directly on a host using ``is_metal``,
a container creates for this component.
the host group by deleting the related file located in the ``env.d/``
directory.
- Do not run the playbook that installs the component.
Unless you specify the component to run directly on a host by using the
``is_metal`` property, a container is created for this component.
- Adjust the
`affinity <http://docs.openstack.org/developer/openstack-ansible/install-guide/app-advanced-config-affinity.html>`_
to 0 for the host group. Similar to the second option listed here, Unless
you specify the component to run directly on a host by using the``is_metal``
property, a container is created for this component.
.. _affinity: app-advanced-config-affinity.rst
Deploy existing components on dedicated hosts
---------------------------------------------
Deploying existing components on dedicated hosts
------------------------------------------------
To deploy a ``shared-infra`` component to dedicated hosts, modify the
files that specify the host groups and container groups for the component.
To deploy a shared-infra component onto dedicated hosts, modify both the
files specifying the host groups and container groups for the component.
For example, to run Galera directly on dedicated hosts, you would perform the
following steps:
For example, to run Galera directly on dedicated hosts the ``container_skel``
segment of the ``env.d/galera.yml`` file might look like:
#. Modify the ``container_skel`` section of the ``env.d/galera.yml`` file.
For example:
.. code-block:: yaml
.. code-block:: yaml
container_skel:
galera_container:
belongs_to:
- db_containers
contains:
- galera
properties:
log_directory: mysql_logs
service_name: galera
is_metal: true
container_skel:
galera_container:
belongs_to:
- db_containers
contains:
- galera
properties:
log_directory: mysql_logs
service_name: galera
is_metal: true
.. note::
.. note::
If you want to deploy within containers on these dedicated hosts, omit the
``is_metal: true`` property. We include it here as a recipe for the more
commonly requested layout.
To deploy within containers on these dedicated hosts, omit the
``is_metal: true`` property.
Since we define the new container group (``db_containers`` above), we must
assign that container group to a host group. To assign the new container
group to a new host group, provide a ``physical_skel`` for the new host group
(in a new or existing file, such as ``env.d/galera.yml``). For example:
#. Assign the ``db_containers`` container group (from the preceding step) to a
host group by providing a ``physical_skel`` section for the host group
in a new or existing file, such as ``env.d/galera.yml``.
For example:
.. code-block:: yaml
.. code-block:: yaml
physical_skel:
db_containers:
belongs_to:
- all_containers
db_hosts:
belongs_to:
- hosts
physical_skel:
db_containers:
belongs_to:
- all_containers
db_hosts:
belongs_to:
- hosts
Lastly, define the host group (db_hosts above) in a ``conf.d/`` file (such as
``galera.yml``):
#. Define the host group (``db_hosts``) in a ``conf.d/`` file (such as
``galera.yml``). For example:
.. code-block:: yaml
.. code-block:: yaml
db_hosts:
db-host1:
ip: 172.39.123.11
db-host2:
ip: 172.39.123.12
db-host3:
ip: 172.39.123.13
db_hosts:
db-host1:
ip: 172.39.123.11
db-host2:
ip: 172.39.123.12
db-host3:
ip: 172.39.123.13
.. note::
.. note::
Each of the custom group names in this example (``db_containers``
and ``db_hosts``) were arbitrary. You can choose your own group names
but be sure the references are consistent between all relevant files.
Each of the custom group names in this example (``db_containers``
and ``db_hosts``) are arbitrary. Choose your own group names,
but ensure the references are consistent among all relevant files.