Rohit Agarwal's Notes

Octopress and Github: WTF is going on with the branches?

29 May 2013

This blog is powered by Octopress and hosted using Github Pages. When I checked the github repository for this blog, I found that there were two branches: master and source. But locally there was only one: source.

$ git branch
* source

To understand what was going on, I dug up the docs.

Initially when you clone the octopress repo from imathis/octopress, the local branch is called master and the remote imathis/octopress is called origin.

The magic happens when you do rake setup_github_pages.

It renames the remote pointing to imathis/octopress from origin to octopress; adds your Github Pages repository as the default origin remote and renames the master branch to source. It then creates a new directory _deploy/ and initializes a new git repository there. Finally, it adds your Github Pages repository as the default origin remote for this new repository also.

Now, when you do rake deploy, the master branch of the git repo in _deploy/ is pushed to the master branch of your Github Pages repo. And when you push the source repo to github, it becomes the source branch of your Github Pages repo.

Here are some more details:

$ cd octopress/  # THE_DIRECTORY_WHERE_YOU_CLONED_OCTOPRESS
$ git remote show origin
* remote origin
  Fetch URL: [email protected]:mindprince/mindprince.github.io.git
  Push  URL: [email protected]:mindprince/mindprince.github.io.git
  HEAD branch: master
  Remote branches:
    master new (next fetch will store in remotes/origin)
    source tracked
  Local ref configured for 'git push':
    source pushes to source (up to date)
$ cd octopress/_deploy/
$ git remote show origin
* remote origin
  Fetch URL: [email protected]:mindprince/mindprince.github.io.git
  Push  URL: [email protected]:mindprince/mindprince.github.io.git
  HEAD branch: master
  Remote branches:
    master tracked
    source new (next fetch will store in remotes/origin)
  Local ref configured for 'git push':
    master pushes to master (up to date)

To summarize, the two branches source and master on your Github Pages repo correspond to two separate git repositories: one in your octopress/ directory and another in the octopress/_deploy/ directory.

The fact that separate git repositories on your local machine can act as different branches of the same repository on github is interesting. It can probably be misused to host more than five private repositories in Github's Micro plan.

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