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.

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.

Virtual environments

Nova development uses a set of shell scripts in DevStack. Virtual environments with venv are also available with the source code.

The easiest way to build a fully functional development environment is with DevStack. Create a machine (such as a VM or Vagrant box) running a distribution supported by DevStack and install DevStack there. For example, there is a Vagrant script for DevStack at https://github.com/jogo/DevstackUp.

Note

If you prefer not to use devstack, you can still check out source code on your local machine and develop from there.

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 libxml2-dev libxslt-dev pkg-config libffi-dev libpq-dev libmysqlclient-dev

On Ubuntu Precise (12.04) you may also need to add the following packages:

sudo apt-get build-dep python-mysqldb

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

sudo yum install python-devel openssl-devel python-pip git gcc libxslt-devel mysql-devel python-pip postgresql-devel libffi-devel
sudo pip-python install tox

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

See unit_tests for details.

Using a remote debugger

Some modern IDE such as pycharm (commercial) or Eclipse (open source) support remote debugging. In order to run nova with remote debugging, start the nova process with the following parameters --remote_debug-host <host IP where the debugger is running> --remote_debug-port <port it is listening on>

Before you start your nova process, start the remote debugger using the instructions for that debugger. For pycharm - http://blog.jetbrains.com/pycharm/2010/12/python-remote-debug-with-pycharm/ For Eclipse - http://pydev.org/manual_adv_remote_debugger.html

More detailed instructions are located here - http://novaremotedebug.blogspot.com

Using fake computes for tests

The number of instances supported by fake computes is not limited by physical constraints. It allows to perform stress tests on a deployment with few resources (typically a laptop). But you must avoid using scheduler filters limiting the number of instances per compute (like RamFilter, DiskFilter, AggregateCoreFilter), otherwise they will limit the number of instances per compute.

Fake computes can also be used in multi hypervisor-type deployments in order to take advantage of fake and "real" computes during tests:

• create many fake instances for stress tests
• create some "real" instances for functional tests

Fake computes can be used for testing Nova itself but also applications on top of it.

Contributing Your Work

Once your work is complete you may wish to contribute it to the project. Refer to HowToContribute for information. Nova uses the Gerrit code review system. For information on how to submit your branch to Gerrit, see GerritWorkflow.