Getting started with development

PlainBox uses python3 for development. The core is really system independent but you will need Ubuntu to really make the best of it and experience it as we do. We encourage everyone to use the most recent Ubuntu release for development. Usually this brings the best, most recent tools without having to search for software on the Internet.

PlainBox has almost no dependencies itself, almost, because we depend on the mighty CheckBox project to provide us with a lot of existing infrastructure. Testing PlainBox requires additional packages and some non-packaged software. You will typically want to install it and take advantage of the integration we provide.

Note

If you are working with the source please be aware that PlainBox requires an installed copy of CheckBox. CheckBox in turns is has many scripts that depend on various system packages, including python packages that cannot be installed from pypi. If you were planning on using virtualenv then please make sure to create it with the --system-site-packages option.

Get the source

Source code for PlainBox is kept along with several other related projects in the checkbox project on launchpad. You will need to use bzr to get a local copy.

$ bzr branch lp:checkbox

Note

If you would rather use git you can also do that (and in fact, some of us already do). Head to git-lp homepage and follow the guide there to use git-lp with this project.

Get the dependencies

You will need some tools to work on CheckBox. Scripted installation of almost everything required is available (except for VirtualBox and Vagrant, those are still manual).

From the top of the checkbox checkout run mk-venv, that script will install all the missing dependencies and set you up for work on your machine.

Getting Vagrant

While developing PlainBox you will often need to run potentially dangerous commands on your system, such as asking it to suspend and wake up automatically. We also need to support a range of Ubuntu releases, going all the way back to Ubuntu 12.04. This may cause compatibility issues that are unnoticed all until they hit our CI system. To minimize this PlainBox uses Vagrant to create lightweight execution environments that transparently share your source tree and allow you to quickly create and share testing environment that can be deployed by any developer in minutes. Vagrant uses VirtualBox and while both are packaged in Ubuntu, unless you are running Ubuntu 13.04 you should download and install the software from their upstream projects.

If you are running Ubuntu 13.04

$ sudo apt-get install vagrant

If you are running earlier version of Ubuntu follow those two links to get started:

If you have not installed VirtualBox before, you must add yourself to the vboxusers group, log out and log back in again.

$ sudo usermod -G vboxusers -a $USER

Initialize virtualenv

PlainBox will use a few unpackaged and bleeding-edge releases from pypi those are installed by additional script. By default the script assumes you have a /ramdisk directory but you can pass any path as an argument for an alternate location.

$ ./mk-venv

After everything is set up you can activate the virtualenv environment with the dot command. Note that there is a space between the dot and the forward slash. You can repeat this command in as many shells as you like.

$ . /ramdisk/venv/bin/activate

Once virtualenv is activated your shell prompt will be changed to reflect that. You should now be able to run plainbox –help to ensure everything is working properly.

Initialize vagrant

Vagrant allows us to ship a tiny text file Vagrantfile that describes the development and testing environment. This file tells vagrant how to prepare a virtual machine for testing. If you never used it before you may want to keep a tab open on vagrant getting started guide

We did all the hard work so that you don’t have to, to get everything ready just run one command:

$ vagrant up

This will download vanilla Ubuntu cloud images, initialize VirtualBox, provision virtual machines (one for each supported Ubuntu release) and allow you to ssh into them for testing with one command.

This will take a moment, depending on the speed of your network. Once that is done you should be able to log into, say, precise and run plainbox –help to see if everything is all right.

$ vagrant ssh precise
vagrant@vagrant-ubuntu-precise-32:~$ plainbox --help
usage: plainbox [-h] [-v] {run,special,self-test} ...

positional arguments:
  {run,special,self-test}
    run                 run a test job
    special             special/internal commands
    self-test           run integration tests

optional arguments:
  -h, --help            show this help message and exit
  -v, --version         show program's version number and exit
$ exit

Running PlainBox tests

PlainBox is designed to be testable so it would be silly if it was hard to run tests. Actually, there are many different ways to run tests. They all run the same code so don’t worry.

To test the current code you are working on you can:

  • Run the ./test-in-vagrant.sh from the top-level directory. This will take the longer but will go over all the tests on all the supported versions of Ubuntu. It will run CheckBox unit-tests, PlainBox unit-tests and it will even run integration tests that actually execute jobs.
  • Run plainbox self-test –unit-tests or plainbox self-test –integration-tests. This will execute all the tests right on your machine, without any virtualization (well, unless you do that after running vagrant ssh). Typically you would run unit tests while being in a virtualenv with the plainbox package in development mode, as created by running python setup.py develop
  • Run ./setup.py test this will install any required test dependencies from pypi and run unit tests.
  • Run the script test-with-coverage.sh while being in a virtualenv. This will also compute testing code coverage and is very much recommended while working on new code and tests.

Submitting Patches

We use Launchpad for most of our project management. All code changes should be submitted as merge requests. Launchpad has extensive documentation on how to use various facilities it provides.

In general we are open to contributions but we reserve the right to reject patches if they don’t fit into the needs of the Hardware Certification. If you have an idea go and talk to us on IRC on the #ubuntu-quality channel.

We have some basic rules patch acceptance:

  1. Be prepare to alter your changes.

    This is a meta-rule. One of the points of code reviews is to improve the proposal. That implies the proposal may need to change. You must be prepared and able to change your code after getting feedback.

    To do that efficiently you must structure your work in a way where each committed change works for you rather than against you. The rules listed below are a reflection of this.

  2. Each patch should be a single logical change that can be applied.

    Don’t clump lots of changes into one big patch. That will only delay review, make accepting feedback difficult and annoying. This may mean that the history has many small patches that can land in trunk in a FIFO mode. The oldest patch of your branch may be allowed to land and should make sense. This has implications on how general code editing should be performed. If you break some APIs then firsts introduce a working replacement, then change usage of the API and lastly remove any dead code.

  3. Don’t keep junk patches in your branch.

    Don’t keep patches such as “fix typo” in your branch, that makes the review process more difficult as some reviewers will read your patches one by one. This is especially important if your changes are substantial.

  4. Don’t merge with trunk, rebase on trunk.

    This way you can keep your local delta as a collection of meaningful, readable patches. Reading the full diff and following the complex merge history (especially for long-lived branches) is difficult in practice.

  5. Keep unrelated changes in separate branches.

    If you ware working on something and found a bug that needed immediate fixing, typo or anything else that is small and quick to fix, do it. Then take that patch out of your development branch and into a dedicated branch and propose it. As the small change is reviewed and lands you can remove that patch from your development branch.

    This is intended to help both the developer and the reviewer. Seemingly trivial patches may turn out to be more complicated than initially assumed (and may have their own feedback cycle and iterations). The reviewer can focus on logical changes and not on a collection of unrelated alterations. Lastly we may need to apply some fixes to other supported branches and release those.

  6. Don’t propose untested code.

    We generally like tests for new code. This is not a super-strict requirement but unless writing tests is incredibly hard we’d rather wait. If testing is hard we’d rather invest some time in refactoring the code or building required support infrastructure.

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