=====================================
Using Kolla For OpenStack Development
=====================================

Kolla-ansible can be used to deploy containers in a way suitable for doing
development on OpenStack services.

.. note::

   This functionality is new in the Pike release.

Heat was the first service to be supported, and so the following will use
submitting a patch to Heat using Kolla as an example.

Only source containers are supported.

.. warning::

   Kolla dev mode is intended for OpenStack hacking or development only.
   Do not use this in production!

Enabling Kolla "dev mode"
-------------------------

To enable dev mode for all supported services, set in
``/etc/kolla/globals.yml``:

.. path /etc/kolla/globals.yml
.. code-block:: yaml

   kolla_dev_mode: true

.. end

To enable it just for heat, set:

.. path /etc/kolla/globals.yml
.. code-block:: yaml

   heat_dev_mode: true

.. end

Usage
-----

When enabled, the source repo for the service in question will be cloned under
``/opt/stack/`` on the target node(s). This will be bind mounted into the
container's virtualenv under the location expected by the service on startup.

After making code changes, simply restart the container to pick them up:

.. code-block:: console

   docker restart heat_api

.. end

Debugging
---------

``remote_pdb`` can be used to perform debugging with Kolla containers. First,
make sure it is installed in the container in question:

.. code-block:: console

   docker exec -it -u root heat_api pip install remote_pdb

.. end

Then, set your breakpoint as follows:

.. code-block:: python

   from remote_pdb import RemotePdb
   RemotePdb('127.0.0.1', 4444).set_trace()

.. end

Once you run the code(restart the container), pdb can be accessed using
``socat``:

.. code-block:: console

   socat readline tcp:127.0.0.1:4444

.. end

Learn more information about `remote_pdb
<https://pypi.org/project/remote-pdb/>`_.
