.. _run:

Running Tenks
=============

Commands
--------

Tenks has a variable ``cmd`` which specifies the command to be run. This
variable can be set in your override file (see :ref:`configuration`). The
possible values it can take are:

* ``deploy``: create a virtual cluster to the specification given. This is the
  default command.
* ``teardown``: tear down any existing virtual cluster with the specification
  given.

Execution
---------

Currently, Tenks does not have a CLI or wrapper. Before running any of the
``ansible-playbook`` commands in this section, ensure that your Tenks
virtualenv is active (see :ref:`installation`). In this section,
``override.yml`` represents the path to your override file (see
:ref:`configuration`).

The ``deploy.yml`` playbook will run deployment from start to finish. This can
be run by calling::

  (tenks) $ ansible-playbook --inventory ansible/inventory ansible/deploy.yml --extra-vars=@override.yml

``teardown.yml`` is ``deploy.yml``'s "mirror image" to tear down a cluster.
This can be run by calling::

  (tenks) $ ansible-playbook --inventory ansible/inventory ansible/teardown.yml --extra-vars=@override.yml

``deploy.yml`` and ``teardown.yml`` automatically set ``cmd`` appropriately,
and they contain various constituent playbooks which perform different parts of
the deployment.  An individual section of Tenks can be run separately by
substituting the path to the playbook(s) you want to run into one of the
commands above.  The current playbooks can be seen in the Ansible structure
diagram in :ref:`architecture`. Bear in mind that you will have to set ``cmd``
in your override file if you are running any of the sub-playbooks individually.

Once a cluster has been deployed, it can be reconfigured by modifying the Tenks
configuration and rerunning ``deploy.yml``. Node specs can be changed
(including increasing/decreasing the number of nodes); node types can also be
reconfigured. Existing nodes will be preserved where possible.