Installation
============

`git-deps` requires [pygit2](http://www.pygit2.org/), which in return
requires [libgit2](https://libgit2.github.com/).  `git-deps` and
pygit2 are both Python modules, but libgit2 is not.  This means
that there are a few ways to approach installation, detailed below.
Corrections and additions to these instructions are very welcome!

Before you pick an option, it is very important to consider that [only
certain combinations of libgit2 and pygit2 will work
together](http://www.pygit2.org/install.html#version-numbers).

## Option 1: Install pygit2 and libgit2 from OS packages, and `git-deps` as a Python module

if you are using Linux, there is a good chance that your distribution
already offers packages for both pygit2 and libgit2, in which case
installing pygit2 from packages should also automatically install
libgit2.  For example, on openSUSE, just do:

    sudo zypper install python-pygit2

or on Debian:

    sudo apt-get install python-pygit2

pygit2's website also has installation instructions for
[Windows](http://www.pygit2.org/install.html#installing-on-windows)
and [Mac OS](http://www.pygit2.org/install.html#installing-on-os-x).

Finally, install `git-deps` via `pip`:

    pip install git-deps

## Option 2: Install libgit2 from OS packages, and `git-deps` / pygit2 as Python modules

In this case it may be enough to install libgit2 via your
distribution's packaging tool, e.g. on openSUSE:

    sudo zypper install libgit2-24

Then install `git-deps` which should also automatically install pygit2
as one of its dependencies:

    pip install git-deps

However be aware that this will pick a pygit2 version based on
`requirements.txt` from `git-deps`, which may not be compatible with
the libgit2 you have installed from OS packages.

## Option 3: Install everything from source

First follow
[the installation instructions for pygit2](http://www.pygit2.org/install.html).

Then clone this repository and follow the standard Python module
installation route, e.g.

    python setup.py install

## Option 4: Installation via Docker

Rather than following the above manual steps, you can try
[an alternative approach created by Paul Wellner Bou which facilitates running `git-deps` in a Docker container](https://github.com/paulwellnerbou/git-deps-docker).
This has been tested on Ubuntu 14.10, where it was used as a way to
circumvent difficulties with installing libgit2 >= 0.22.

However, at the time of writing, [this repository needs to be adapted
to the module-based installation
mechanism](https://github.com/paulwellnerbou/git-deps-docker/issues/2)
which was [recently introduced to
`git-deps`](https://github.com/aspiers/git-deps/pull/71).

## Check installation

Now `git-deps` should be on your `$PATH`, which means that executing
it and also `git deps` (with a space, not a hyphen) should both work.

## Install support for web-based graph visualization (`--serve` option)

The web-based graph visualization code uses Javascript and relies on
many third-party modules.  If you've installed `git-deps` via `pip`
then these files should all be magically installed without any extra
effort, so you can skip reading the rest of this section.

If however you are installing `git-deps` from source and you want to
use the shiny new graph visualization web server functionality, you
will need to fetch these Javascript libraries yourself.  Currently
only one approach to installation is listed below, but any Javascript
experts who have suggestions about other ways to install are [warmly
encouraged to submit them](CONTRIBUTING.md).

*   Install `browserify`.  For example (at least on Linux) if you want
    it to be accessible directly from the command-line then you can
    use the `-g` option of `npm` by running this as `root`:

         npm install -g browserify

*   To install the required Javascript libraries, you will need
    [`npm`](https://www.npmjs.com/) installed, and then type:

        cd git_deps/html
        npm install
        browserify -t coffeeify -d js/git-deps-graph.coffee -o js/bundle.js

    (If you are developing `git-deps` then replace `browserify` with
    `watchify -v` in order to continually regenerate `bundle.js`
    whenever any of the input files change.)

*   You will need the [Flask](http://flask.pocoo.org/) Python
    module installed.

Now you should be able to run `git deps --serve` and point your
browser at the URL it outputs.