Pip and Github Clone URLs

Using the basic git protocol, as opposed to SSH or HTTPS is a reliable but undocumented way of getting read-only access to Github repositories.

Cloning a Github Repository

Github advertises two clone URLs for repositories: SSH and HTTPS. The usage, and benefits of each is explained on the Github help pages. An undocumented third option is to use the git protocol directly. For the repository goerz/mgplottools, three equivalent possibilities are:

git clone [email protected]:goerz/mgplottools.git
git clone https://github.com/goerz/mgplottools.git
git clone git://github.com/goerz/mgplottools.git

Note that the .git at the end of the url is optional. The SSH access is the most convenient if you have SSH set up properly. HTTPS is the most flexible, and the git protocol is for read-only access.

Pip Installation from Github

For installing a Python package from a github repository, pip can be be called with any of the three protocols:

pip install git+ssh://[email protected]/goerz/mgplottools.git@master#egg=mgplottools
pip install git+https://github.com/goerz/mgplottools.git@master#egg=mgplottools
pip install git+git://github.com/goerz/mgplottools.git@master#egg=mgplottools

Again, .git can be omitted. Also the commit (@master) and package information (#egg=mgplottols) can be omitted in certain circumstances, see the pip documentation.

When simply installing a package in this way, read-only access is the only thing required. In principle, HTTPS should do the right thing, but I have observed pip to prompt for a Github username and password when trying to clone a repository that happens to be under your own Github account (i.e. where you have read and write access). This can create significant problems when pip install is called from an installation script, where no user-interaction is possible. The "smart" HTTPS access is trying to be too smart for its own good in this case.

Therefore, firewall-rules permitting, using pip in combination with the plain git protocol should be the preferred method in installation scripts (or IPython notebooks).