This project assumes you have a basic knowledge of how ansible works and have already prepared your hosts for
configuration by ansible.
After you've cloned the ``ceph-ansible`` repository, selected your branch and installed ansible then you'll need to create
your inventory file, playbook and configuration for your ceph cluster.
Inventory
---------
The ansible inventory file defines the hosts in your cluster and what roles each host plays in your ceph cluster. The default
location for an inventory file is ``/etc/ansible/hosts`` but this file can be placed anywhere and used with the ``-i`` flag of
ansible-playbook. An example inventory file would look like::
[mons]
mon1
mon2
mon3
[osds]
osd1
osd2
osd3
..note::
For more information on ansible inventories please refer to the ansible documentation: http://docs.ansible.com/ansible/latest/intro_inventory.html
Playbook
--------
You must have a playbook to pass to the ``ansible-playbook`` command when deploying your cluster. There is a sample playbook at the root of the ``ceph-ansible``
project called ``site.yml.sample``. This playbook should work fine for most usages, but it does include by default every daemon group which might not be
appropriate for your cluster setup. Perform the following steps to prepare your playbook:
The configuration for your ceph cluster will be set by the use of ansible variables that ``ceph-ansible`` provides. All of these options and their default
values are defined in the ``group_vars/`` directory at the root of the ``ceph-ansible`` project. Ansible will use configuration in a ``group_vars/`` directory
that is relative to your inventory file or your playbook. Inside of the ``group_vars/`` directory there are many sample ansible configuration files that relate
to each of the ceph daemon groups by their filename. For example, the ``osds.yml.sample`` contains all the default configuation for the OSD daemons. The ``all.yml.sample``
file is a special ``group_vars`` file that applies to all hosts in your cluster.
..note::
For more information on setting group or host specific configuration refer to the ansible documentation: http://docs.ansible.com/ansible/latest/intro_inventory.html#splitting-out-host-and-group-specific-data
At the most basic level you must tell ``ceph-ansible`` what version of ceph you wish to install, the method of installation, your clusters network settings and
how you want your OSDs configured. To begin your configuration rename each file in ``group_vars/`` you wish to use so that it does not include the ``.sample``
at the end of the filename, uncomment the options you wish to change and provide your own value.
An example configuration that deploys the upstream ``jewel`` version of ceph with OSDs that have collocated journals would look like this in ``group_vars/all.yml``::
The supported method for defining your ceph.conf is to use the ``ceph_conf_overrides`` variable. This allows you to specify configuration options using
an INI format. This variable can be used to override sections already defined in ceph.conf (see: ``roles/ceph-common/templates/ceph.conf.j2``) or to provide
new configuration options. The following sections in ceph.conf are supported: [global], [mon], [osd], [mds] and [rgw].
