nova/doc/source/devref/development.environment.rst

Setting Up a Development Environment

This page describes how to setup a working Python development environment that can be used in developing nova on Ubuntu, Fedora or Mac OS X. These instructions assume you're already familiar with git. Refer to GettingTheCode for additional information.

Following these instructions will allow you to run the nova unit tests. If you want to be able to run nova (i.e., launch VM instances), you will also need to install libvirt and at least one of the supported hypervisors. Running nova is currently only supported on Linux, although you can run the unit tests on Mac OS X. See ../quickstart for how to get a working version of OpenStack Compute running as quickly as possible.

Virtual environments

Nova development uses virtualenv to track and manage Python dependencies while in development and testing. This allows you to install all of the Python package dependencies in a virtual environment or "virtualenv" (a special subdirectory of your nova directory), instead of installing the packages at the system level.

Note

Virtualenv is useful for running the unit tests, but is not typically used for full integration testing or production usage.

Linux Systems

Note

This section is tested for Nova on Ubuntu (10.10-64) and Fedora-based (RHEL 6.1) distributions. Feel free to add notes and change according to your experiences or operating system.

Install the prerequisite packages.

On Ubuntu:

sudo apt-get install python-dev libssl-dev python-pip git-core

On Fedora-based distributions (e.g., Fedora/RHEL/CentOS/Scientific Linux):

sudo yum install python-devel openssl-devel python-pip git

Mac OS X Systems

Install virtualenv:

sudo easy_install virtualenv

Check the version of OpenSSL you have installed:

openssl version

If you have installed OpenSSL 1.0.0a, which can happen when installing a MacPorts package for OpenSSL, you will see an error when running nova.tests.auth_unittest.AuthTestCase.test_209_can_generate_x509.

The stock version of OpenSSL that ships with Mac OS X 10.6 (OpenSSL 0.9.8l) or Mac OS X 10.7 (OpenSSL 0.9.8r) works fine with nova.

Getting the code

Grab the code from GitHub:

git clone https://github.com/openstack/nova.git
cd nova

Running unit tests

The unit tests will run by default inside a virtualenv in the .venv directory. Run the unit tests by doing:

./run_tests.sh

The first time you run them, you will be asked if you want to create a virtual environment (hit "y"):

No virtual environment found...create one? (Y/n)

See unit_tests for more details.

Manually installing and using the virtualenv

You can manually install the virtual environment instead of having run_tests.sh do it for you:

python tools/install_venv.py

This will install all of the Python packages listed in the tools/pip-requires file into your virtualenv. There will also be some additional packages (pip, distribute, greenlet) that are installed by the tools/install_venv.py file into the virutalenv.

If all goes well, you should get a message something like this:

Nova development environment setup is complete.

To activate the Nova virtualenv for the extent of your current shell session you can run:

$ source .venv/bin/activate

Or, if you prefer, you can run commands in the virtualenv on a case by case basis by running:

$ tools/with_venv.sh <your command>

Contributing Your Work

Once your work is complete you may wish to contribute it to the project. Add your name and email address to the Authors file, and also to the .mailmap file if you use multiple email addresses. Your contributions can not be merged into trunk unless you are listed in the Authors file. Nova uses the Gerrit code review system. For information on how to submit your branch to Gerrit, see GerritWorkflow.