OpenStack is a somehow complex thing to setup and to integrate into Linux distributions. Thus, I proposed an OpenStack testing hackfest at Flock, to test the latest build for Fedora, and also to bring users and developers together into one room. Currently, it is not decided, if this session is accepted, so please stay tuned.

Let’s say, one needs to create a corporate theme, named horizon_bigcorp. Then we first need to change local_settings.py. In Fedora and EPEL, that file is located at /etc/openstack-dashboard/local_settings

Append the following lines to that file

THEME_APP = 'horizon_bigcorp'

try:
    __import__(THEME_APP)
    INSTALLED_APPS = (THEME_APP,) + INSTALLED_APPS
except:
    pass

Then we’ll create a customization app:

├── __init__.py
├── __init__.pyc
├── models.py
├── models.pyc
├── static
│   └── dashboard
│       ├── img
│       │   ├── bigcorpfavicon.ico
│       │   └── bigcorplogo.png
│       └── less
│           └── bigcorptheme.less
└── templates
    ├── horizon
    │   └── common
    │       └── _sidebar.html
    └── _stylesheets.html

7 directories, 9 files

Those .py files just need to be empty files.
The magic is in _stylesheets.html, it’s basically a modified copy of file openstack_dashboard/templates/_stylesheets.html:

{% load compress %}

{% compress css %}
<link href='{{ STATIC_URL }}dashboard/less/horizon.less' type='text/less' media='screen' rel='stylesheet' />
{% endcompress %}

<link rel="shortcut icon" href="{{ STATIC_URL }}dashboard/img/favicon.ico"/>

Note, you just need a customized theme.less, if you did changes at css (most likely). Like stylesheets, theme.less is a modified copy of it’s counterpart taken from the openstack_dashboard directory.

Another example, how this can be implemented can be found here: https://github.com/mrunge/horizon/tree/customization, where I modified settings.py instead of changing local_settings.py.example

Many developers recommend using devstack to work on OpenStack. For some reasons, I can’t recommend that for Dashboard. My colleague Dan Berrange has an article with all dirty details.

Good news is, at least for OpenStack’s dashboard, devstack is not required in any case, it just runs on plain Fedora. I simply followed the instructions provided for Fedora’s test day, and they worked great for me, no rocket science and no engineering master required.

Additionally I installed git and git-review (as root):
yum -y install git git-review
then go to the location where you want to put the code, for me that’s
cd ~/work

and execute
git clone https://github.com/openstack/horizon.git && cd horizon

This will get the source code from github, will create a new directory named horizon, and change to that directory.
./manage.py runserver

starts Django’s built in development server on your host, per default on port 8000.

To visit your shiny Dashboard, direct your webbrowser to http://localhost:8000 .

When finished with your desired changes, you should submit them for review. The process around that is covered here: http://wiki.openstack.org/GerritWorkflow