Developer Guide

Developer quick-start

Setting Up a Development Environment

This page describes how to setup a working Python development environment that can be used in developing MagnetoDB on Ubuntu. These instructions assume you’re already familiar with git. Following these instructions will allow you to run the MagnetoDB unit tests. If you want to be able to run MagnetoDB, you will also need to install Cassandra and Devstack.

Virtual environments

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 here. You can also use this documentation.

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 MagnetoDB on Ubuntu (12.04-64) distribution. Feel free to add notes and change according to your experiences or operating system.

Install the prerequisite packages:

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

Getting the code

Grab the code from GitHub:

$ git clone
$ cd magnetodb

Running unit tests

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

$ ./

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 do it for you:

$ python tools/

This will install all of the Python packages listed in the requirements.txt file and also those listed in the test-requirements.txt file into your virtualenv. There will also be some additional packages (pip, setuptools, greenlet) that are installed by the tools/ file into the virutalenv.

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

MagnetoDB development environment setup is complete.

To activate the MagnetoDB 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/ <your command>

Remote development

Some modern IDE such as PyCharm (commercial/open source) support remote developing. Some useful links:

Also, watch this video setting up dev environment for cases when MagnetoDB installed on the separate machines with Devstack:

MagnetoDB dev env configuration

Contributing Your Work

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

Unit Tests

MagnetoDB contains a suite of unit tests, in the /magnetodb/tests/unittests directory.

Any proposed code change will be automatically rejected by the OpenStack Jenkins server if the change causes unit test failures.

Preferred way to run the tests

The preferred way to run the unit tests is using tox. See the unit testing section of the Testing wiki page for more information.

To run the Python 2.7 tests:

$ tox -e py27

To run the style tests:

$ tox -e pep8

You can request multiple tests, separated by commas:

$ tox -e py27, pep8

Older way to run the tests

Using tox is preferred. It is also possible to run the unit tests using the script found at the top level of the project. The remainder of this document is focused on

Run the unit tests by doing:

$ ./

This script is a wrapper around the testr test runner and the flake8 checker.


The script supports several flags. You can view a list of flags by doing:

$ ./ -h

This will show the following help information:

Usage: ./ [OPTION]...
Run MagnetoDB's test suite(s)

 -V, --virtual-env        Use virtualenv.  Install automatically if not present.
                          (Default is to run tests in local environment)
 -F, --force              Force a clean re-build of the virtual environment. Useful when dependencies have been added.
 -f, --func               Functional tests have been removed.
 -u, --unit               Run unit tests (default when nothing specified)
 -p, --pep8               Run pep8 tests
 --all                    Run pep8 and unit tests
 -c, --coverage           Generate coverage report
 -d, --debug              Run tests with testtools instead of testr. This allows you to use the debugger.
 -h, --help               Print this usage message

Because is a wrapper around testrepository, it also accepts the same flags as testr. See the testr user manual for details about these additional flags.

Running a subset of tests

Instead of running all tests, you can specify an individual directory, file, class, or method that contains test code.

To run the tests in the /magnetodb/tests/unittests/api/openstack/v1 directory:

$ ./ v1

To run the tests in the /magnetodb/tests/unittests/api/openstack/v1/ file:

$ ./ test_get_item

To run the tests in the GetItemTestCase class in /magnetodb/tests/unittests/api/openstack/v1/

$ ./ test_get_item.GetItemTestCase

To run the GetItemTestCase.test_get_item test method in /magnetodb/tests/unittests/api/openstack/v1/

$ ./ test_get_item.GetItemTestCase.test_get_item

Also note, that as all these tests (using tox or are run by testr test runner, it is not possible to use pdb breakpoints in tests or the code being tested. To be able to use debugger breakpoints you should directly use testtools as in the following:

$ python -m magnetodb.tests.unittests.test_get_item.GetItemTestCase.test_get_item


By default, the tests use the Python packages installed inside a virtualenv. (This is equivalent to using the -V, –virtualenv flag).

If you wish to recreate the virtualenv, call with the flag:

-f, --force

Recreating the virtualenv is useful if the package dependencies have changed since the virtualenv was last created. If the requirements.txt or tools/ files have changed, it’s a good idea to recreate the virtualenv.

Integration and functional tests

MagnetoDB contains a suite of integration tests (in the /magnetodb/tests/storage directory) and functional tests (in the /tempest directory).

Any proposed code change will be automatically rejected by the OpenStack Jenkins server if the change causes unit test failures.

Refer to Tests on environment with devstack for information, how to install and set environment and how to run such kind of tests.

Other Resources

Project hosting with Launchpad

Launchpad hosts the MagnetoDB project. The MagnetoDB project homepage on Launchpad is .

Launchpad credentials

Creating a login on Launchpad is important even if you don’t use the Launchpad site itself, since Launchpad credentials are used for logging in on several OpenStack-related sites. These sites include:

Mailing list

The mailing list email is This is a common mailing list across the OpenStack projects. To participate in the mailing list:

The mailing list archives are at

Bug tracking

Report MagnetoDB bugs at

Feature requests (Blueprints)

MagnetoDB uses Launchpad Blueprints to track feature requests. Blueprints are at

Technical support (Answers)

MagnetoDB uses Ask OpenStack (which are not hosted on Launchpad) to track MagnetoDB technical support questions.

Code Reviews with Gerrit

MagnetoDB uses the Gerrit tool to review proposed code changes. The review site is

Gerrit is a complete replacement for Github pull requests. All Github pull requests to the MagnetoDB repository will be ignored.

See How to Contribute for information about how to get started using Gerrit. See Gerrit Workflow Quick Reference and Gerrit, Jenkins and Github for more detailed documentation on how to work with Gerrit.

Also, look at Code Review Guidelines.

Continuous Integration with Jenkins

MagnetoDB uses a Jenkins server to automate development tasks. The Jenkins front-end is at You must have an account on Launchpad to be able to access the OpenStack Jenkins site.

Jenkins performs tasks such as running static code analysis, running unit tests, and running functional tests. For more details on the jobs being run by Jenkins, see the code reviews on Tests are run automatically and comments are put on the reviews automatically with the results.

You can also get a view of the jobs that are currently running from the zuul status dashboard,

How to contribute to MagnetoDB

Improve MagnetoDB

Where can I discuss & propose changes?

Our IRC channel: IRC server #magnetodb on
Openstack mailing list: (see subscription and usage instructions).
MagnetoDB team on Launchpad: Questions&Answers/Bugs/Blueprints.

How can I start?

It is extremely simple to participate in different MagnetoDB development lines. MagnetoDB Launchpad page contains a wide range of tasks perfectly suited for you to start contributing to MagnetoDB. You can choose any unassigned bug or blueprint. As soon as you have chosen a bug, just assign it to you, and you can start fixing it. If you would like chose a blueprint, please contact core team at the #magnetodb IRC channel on

The most bugs and blueprints contain basic descriptions of what is to be done there; in case you have questions or want to share your ideas, be sure to contact us in IRC.

How to contribute?

1. First of all you need a Launchpad account. Make sure Launchpad has your SSH key, Gerrit (the code review system) uses this.

2. Sign the Contributors License Agreement as outlined in section 3 of the How To Contribute wiki page.

3.Tell git your details:

$ git config --global "Firstname Lastname"
$ git config --global ""

4.Install git-review. This tool takes a lot of the pain out of remembering commands to push code up to Gerrit for review and to pull it back down to edit it. It is installed using:

$ pip install git-review

NOTE: Several Linux distributions (notably Fedora 16 and Ubuntu 12.04) are also starting to include git-review in their repositories so it can also be installed using the standard package manager.

5.Grab the MagnetoDB repository:

$ git clone

6.Checkout a new branch to hack on:

$ git checkout -b TOPIC-BRANCH
  1. Start coding.

8.Run the test suite locally to make sure nothing broke, e.g.:

$ ./

or you can use tox test command line tool (install it with pip install tox).

NOTE: If you extend MagnetoDB with new functionality, make sure you also have provided unit tests for it.

9.Commit your work using:

$ git commit -a

or you can use the following to edit a previous commit:

$ git commit -a --amend

NOTE: Make sure you have supplied your commit with a neat commit message, containing a link to the corresponding blueprint/bug, if appropriate.

10.Push the commit up for code review using:

$ git review

That is the awesome tool you installed earlier that does a lot of hard work for you.

11.Watch your email or review site, it will automatically send your code for a battery of tests on our Jenkins setup and the core team for the project will review your code. If there is any changes that should be made they will let you know.

12.When all is good the review site will automatically merge your code.

(This tutorial is based on:

Code Review Guidelines


Any policy or guidelines form something intangible, often called “culture” or “mentality”. They effectively promote values accepted by a community or a working group. I consider such stuff as very important for any long-term project success. So I volunteered to help with this corner-stone document.

Of course this is a draft and can and must be discussed. Please come to the project IRC channel #magnetodb on FreeNode server.

Values we ... hm ... value

Excellence, even small typo can change or even ruin a newcomer’s perception.

Openness, we believe the more people contribute their best the better our product will be.

Easiness, it should be easy to start, easy to excel, easy to be happy in this big world :-)

We encourage (+1) these things

The change makes code/documents/design ...

Easier to understand

... to read (including typos)

... to maintain in the future

Better in terms of performance

... Scalability

... Simplicity

We discourage (-1) these things

The changes make code/documents/design ...

... Opposite of values above :)

Especially ...

There is no description what inside and why the change should be accepted.

There is no reference to a bug or a blueprint to track discussions, decisions, and history.

There are grammar or syntax errors.

The change is too big to be reviewed without extra efforts. It’s recommended to chop design into small chunks gathered into super-blueprint to provide a big picture.

Source documentation