Online hosting and collaboration

As well as managing our own codes and documents, another important use of version control is for collaboration...

Online hosting

As already discussed, Git uses a “distributed” model that allows everyone working on a project to have their own independent copy of the entire repository. To collaborate effectively though we need a central version of the code base which is used to unify everyones’ efforts. Typically the best place for such a central repository is online.

There are a number of excellent options for online hosting of git repositories (for a list see this Wikipedia entry). However, there are two options in particular which stand out in my opinion:

• Bitbucket: This site overs unlimited free public repositories (where anyone can see and checkout your project). If you have an email address from an academic institution though, then you can also get unlimited free private repositories! These repositories only allow users who you specify to have access.
• Github: This is site also offers unlimited free public repositories. With an academic institution email address you can also get 5 free private repositories. Github is probably the place for new open source software and tools. It’s a fantastic service and well worth using, especially if you want to take your own code open source. You can also use Github to serve web pages for free. This tutorial is open sourced on Github.

Cloning a repository

If you have the address (and correct permissions) for an online repository then you can grab your own copy using the clone command. Try cloning your own copy of the source for this tutorial (make sure you are not in your a_paper repository when you do this):

% git clone git://github.com/AstroinformaticsAU/VersionControlTutorial.git
% cd VersionControlTutorial

You are now inside your own personal copy of the repository and can do whatever you want with it. Try:

% git log

and you will see that you also have the full commit history.

Collaboration strategies

Unfortunately, it is out-with the scope of this tutorial to cover all of the different ways you can collaborate with Git. There are a number of options for how to get your changes incorporated into the central repository for everyone to have access to. These include, forking and pull requests, email patches, and direct pushing.

The basic work-flow is almost always the same though:

• Make your changes in your own personal copy of the repository, ideally in a new branch.
• “Pull” (using the command git pull) the most recent version of the central repository into your master branch. This makes sure you are up-to-date with any changes which were made by someone else subsequent to when you last pulled (or made your original clone).
• Merge your changes from your new branch into master.
• Once any conflicts are resolved you can update the central repository with your new code (using for example git push).

Further reading

For a proper introduction to hosting and collaborating with Git, see the excellent online book, Pro Git. The help pages of Github are also an excellent resource.