Deploying with Heat Templates
=============================

It is possible to use the ``--templates`` and ``--environment-file``
options to override specific templates or even deploy using a separate
set of templates entirely.


Deploying an Overcloud using the default templates
--------------------------------------------------

The ``--templates`` option without an argument enables deploying using
the packaged Heat templates::

    openstack overcloud deploy --templates

.. note::

    The default location for the templates is
    `/usr/share/openstack-tripleo-heat-templates`.


Overriding specific templates with local versions
-------------------------------------------------

You may use heat environment files (via the ``--environment-file`` or ``-e``
option), combined with the ``--templates`` option to override specific
templates, e.g to test a bugfix outside of the location of the packaged
templates.

The mapping between heat resource types and the underlying templates can be
found in
`/usr/share/\
openstack-tripleo-heat-templates/overcloud-resource-registry-puppet.yaml`

Here is an example of copying a specific resource template and overriding
so the deployment uses the local version::

    mkdir local_templates
    cp /usr/share/openstack-tripleo-heat-templates/puppet/controller-puppet.yaml local_templates
    cat > override_templates.yaml << EOF
    resource_registry:
        OS::TripleO::Controller: local_templates/controller-puppet.yaml
    EOF
    openstack overcloud deploy --templates --environment-file override_templates.yaml

.. note::

    The ``--environment-file``/``-e`` option may be specified multiple times,
    if duplicate keys are specified in the environment files, the last one
    takes precedence.

.. note::

    You must also pass the environment files (again using the ``-e`` or
    ``--environment-file`` option) whenever you make subsequent changes to the
    overcloud, such as :doc:`../post_deployment/scale_roles`,
    :doc:`../post_deployment/delete_nodes` or
    :doc:`../post_deployment/package_update`.

.. _custom-template-location:

Using a custom location for all templates
-----------------------------------------

You may specify a path to the ``--templates`` option, such that the packaged
tree may be copied to another location, which is useful e.g for developer usage
where you wish to check the templates into a revision control system.

.. note::

    Use caution when using this approach as you will need to rebase any local
    changes on updates to the openstack-tripleo-heat-templates package, and
    care will be needed to avoid modifying anything in the tree which the CLI
    tools rely on (such as top-level parameters).  In many cases using the
    :doc:`ExtraConfig <extra_config>` interfaces or specific template overrides
    as outlined above may be preferable.

Here is an example of copying the entire tripleo-heat-templates tree to a
local directory and launching a deployment using the new location::

    cp -r /usr/share/openstack-tripleo-heat-templates /home/stack/
    openstack overcloud deploy --templates /home/stack/openstack-tripleo-heat-templates