68e3f202b4
The documentation of the inventory started to be spread out, but also massive to be inside one page. This moves it to the inventory section of the reference, but at the same time, to improve readability, moves the previous content into sub pages. Change-Id: If2c6b83abafdc66879d818df4c9690142389a965
100 lines
4.6 KiB
ReStructuredText
100 lines
4.6 KiB
ReStructuredText
.. _inventory-in-depth:
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Understanding the inventory
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===========================
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The default layout of containers and services in OpenStack-Ansible (OSA) is
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determined by the ``/etc/openstack_deploy/openstack_user_config.yml`` file and
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the contents of both the ``/etc/openstack_deploy/conf.d/`` and
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``/etc/openstack_deploy/env.d/`` directories. You use these sources to define
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the *group* mappings that the playbooks use to target hosts and containers for
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roles used in the deploy.
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* You define host groups, which gather the target hosts into *inventory
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groups*, through the ``/etc/openstack_deploy/openstack_user_config.yml``
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file and the contents of the ``/etc/openstack_deploy/conf.d/`` directory.
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* You define *container groups*, which can map from the service components
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to be deployed up to host groups, through files in the
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``/etc/openstack_deploy/env.d/`` directory.
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To customize the layout of the components for your deployment, modify the
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host groups and container groups appropriately before running the installation
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playbooks.
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.. _inventory-confd:
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Understanding host groups (conf.d structure)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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As part of the initial configuration, each target host appears either in the
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``/etc/openstack_deploy/openstack_user_config.yml`` file or in files within
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the ``/etc/openstack_deploy/conf.d/`` directory. The format used for files in
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the ``conf.d/`` directory is identical to the syntax used in the
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``openstack_user_config.yml`` file.
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In these files, the target hosts are listed under one or more
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headings, such as ``shared-infra_hosts`` or ``storage_hosts``, which serve as
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Ansible group mappings. These groups map to the physical
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hosts.
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The ``haproxy.yml.example`` file in the ``conf.d/`` directory provides
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a simple example of defining a host group (``haproxy_hosts``) with two hosts
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(``infra1`` and ``infra2``).
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The ``swift.yml.example`` file provides a more complex example. Here, host
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variables for a target host are specified by using the ``container_vars`` key.
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OpenStack-Ansible applies all entries under this key as host-specific
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variables to any component containers on the specific host.
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.. note::
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To manage file size, we recommend that you define new inventory groups,
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particularly for new services, by using a new file in the
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``conf.d/`` directory.
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.. _inventory-envd:
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Understanding container groups (env.d structure)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Additional group mappings are located within files in the
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``/etc/openstack_deploy/env.d/`` directory. These groups are treated as
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virtual mappings from the host groups (described above) onto the container
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groups, that define where each service deploys. By reviewing files within the
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``env.d/`` directory, you can begin to see the nesting of groups represented
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in the default layout.
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For example, the ``shared-infra.yml`` file defines a container group,
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``shared-infra_containers``, as a subset of the ``all_containers``
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inventory group. The ``shared- infra_containers`` container group is
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mapped to the ``shared-infra_hosts`` host group. All of the service
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components in the ``shared-infra_containers`` container group are
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deployed to each target host in the ``shared-infra_hosts host`` group.
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Within a ``physical_skel`` section, the OpenStack-Ansible dynamic inventory
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expects to find a pair of keys. The first key maps to items in the
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``container_skel`` section, and the second key maps to the target host groups
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(described above) that are responsible for hosting the service component.
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To continue the example, the ``memcache.yml`` file defines the
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``memcache_container`` container group. This group is a subset of the
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``shared-infra_containers`` group, which is itself a subset of
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the ``all_containers`` inventory group.
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.. note::
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The ``all_containers`` group is automatically defined by OpenStack-Ansible.
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Any service component managed by OpenStack-Ansible maps to a subset of the
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``all_containers`` inventory group, directly or indirectly through
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another intermediate container group.
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The default layout does not rely exclusively on groups being subsets of other
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groups. The ``memcache`` component group is part of the ``memcache_container``
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group, as well as the ``memcache_all`` group and also contains a ``memcached``
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component group. If you review the ``playbooks/memcached-install.yml``
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playbook, you see that the playbook applies to hosts in the ``memcached``
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group. Other services might have more complex deployment needs. They define and
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consume inventory container groups differently. Mapping components to several
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groups in this way allows flexible targeting of roles and tasks.
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