HackingHowto

Hacking HOWTO

So you want to hack on GNU MediaGoblin?

First thing to do is check out the web site where we list all the project infrastructure including:

• the IRC channel
• the mailing list
• the issue tracker

Additionally, we have information on how to get involved, who to talk to, what needs to be worked on, and other things besides!

Second thing to do is take a look at codebase chapter where we've started documenting how GNU MediaGoblin is built and how to add new things.

Third you'll need to get the requirements.

Fourth, you'll need to build a development environment. We use an in-package checkout of virtualenv. This isn't the convenional way to install virtualenv (normally you don't install virtualenv inside the package itself) but we've found that it's significantly easier for newcomers who aren't already familiar with virtualenv. If you *are* already familiar with virtualenv, feel free to just install mediagoblin in your own virtualenv setup... the necessary adjustments should be obvious.

Getting requirements

First, you need to have the following installed before you can build an environment for hacking on GNU MediaGoblin:

• Python 2.6 or 2.7 - http://www.python.org/ (You'll need Python as well as the dev files for building modules.)
• python-lxml - http://lxml.de/
• git - http://git-scm.com/
• MongoDB - http://www.mongodb.org/
• Python Imaging Library (PIL) - http://www.pythonware.com/products/pil/
• virtualenv - http://www.virtualenv.org/

Note, MongoDB can get to be pretty huge. You might want to consider looking at Scaling Down if you are installing this on a smallish instance.

GNU/Linux

Debian and derivatives

If you're running Debian GNU/Linux or a Debian-derived distribution such as Debian, Mint, or Ubuntu 10.10+, running the following should install these requirements:

sudo apt-get install mongodb git-core python python-dev python-lxml python-imaging python-virtualenv

Fedora / RedHat(?)

On Fedora:

yum install mongodb-server python-paste-deploy python-paste-script git-core python python-devel python-lxml python-imaging python-virtualenv

Mac OS X

On Mac OS X Lion:

Download the Newest Python.

Git is already installed.

Install MongoDB from these instructions: http://www.mongodb.org/display/DOCS/Quickstart+OS+X

Python-lxml: http://muffinresearch.co.uk/archives/2009/03/05/install-lxml-on-osx/ with sudo

Python Imaging Library (PIL): http://code.google.com/appengine/docs/python/images/installingPIL.html#mac

Libjpeg & Libpng: http://ethan.tira-thompson.org/Mac_OS_X_Ports.html Combo Installer

---

You can help:

If you have instructions for other GNU/Linux distributions, Windows, or Mac OS X to set up requirements, let us know!

How to set up and maintain an environment for hacking with virtualenv

Requirements

No additional requirements.

Create a development environment

After installing the requirements, follow these steps:

1. Clone the repository: git clone git://gitorious.org/mediagoblin/mediagoblin.git
2. Set up the in-package virtualenv: virtualenv . && ./bin/python setup.py develop

That's it!

(If you have troubles in the remaining steps, consider try installing virtualenv with one of the flags --setuptools, --distribute or possibly --no-site-packages. Additionally, if your system has python3.X as the default, you might need to do virtualenv --python=python2.7 or --python=python2.6)

If you have problems, please let us know!

Updating for dependency changes

While hacking on GNU MediaGoblin over time, you'll eventually have to update your development environment because the dependencies have changed.

To do that, run:

./bin/python setup.py develop --upgrade && ./bin/gmg migrate.

Updating for code changes

You don't need to do anything---code changes are automatically available as long as you're doing a git pull or etc.

Running Mongo Database

Startup the Database if you haven't already. On most systems, this should be started automatically. If not, consult the documentation for your distribution or the MongoDB docs themselves.

Running the server

If you want to get things running quickly and without hassle, just run:

./lazyserver.sh.

This will start up a python server where you can begin playing with mediagoblin. It will also run celery in "always eager" mode so you don't have to start a separate process for it.

By default, the instance is not sending out confirmation mails. Instead they are redirected to the standard output (the console) of lazyserver.sh.

You can change this behavior setting email_debug_mode to false in mediagoblin.ini

This is fine in development, but if you want to actually run celery separately for testing (or deployment purposes), you'll want to run the server independently:

./bin/paster serve paste.ini --reload

Running celeryd

If you aren't using ./lazyserver.sh or otherwise aren't running celery in always eager mode, you'll need to do this if you want your media to process and actually show up. It's probably a good idea in development to have the web server (above) running in one terminal and celeryd in another window.

Run:

CELERY_CONFIG_MODULE=mediagoblin.init.celery.from_celery ./bin/celeryd

Running the test suite

Run:

./runtests.sh

Running a shell

If you want a shell with your database pre-setup and an instantiated application ready and at your fingertips....

Run:

./bin/gmg shell

Troubleshooting

pymongo.errors.AutoReconnect: could not find master/primary

If you see this:

   pymongo.errors.AutoReconnect: could not find master/primary

then make sure mongodb is installed and running.

If it's installed, check the mongodb log. On my machine, that's /var/log/mongodb/mongodb.log. If you see something like:

   old lock file: /var/lib/mongodb/mongod.lock.  probably means...

in that case you might have had an unclean shutdown. Try:

sudo mongod --repair

If that didn't work, just delete the lock file and relaunch mongodb.

Anyway, then start the mongodb server in whatever way is appropriate for your distro / OS.

Wiping your user data

You can completely wipe all data from the instance by doing:

gmg wipealldata

Note:

Unless you're doing development and working on and testing creating a new instance, you will probably never have to do this. Will plans to do this work and thus he documented it.

Quickstart for Django programmers

We're not using Django, but the codebase is very Django-like in its structure.

• routing.py is like urls.py in Django
• models.py has mongokit ORM definitions
• views.py is where the views go

We're using MongoDB. Basically, instead of a relational database with tables, you have a big JSON structure which acts a lot like a Python dict.

YouCanHelp

If there are other things that you think would help orient someone new to GNU MediaGoblin but coming from Django, let us know!

Bite-sized bugs to start with

Now you should visit our latest list of bite-sized issues because squishing bugs is messy fun. If you're interested in other things to work on, or need help getting started on a bug, let us know on the mailing list or on the IRC channel.