Upgrade `gitlab-markup` to 1.7.0

The new version requires `python3` to be available. In omnibus
installation this is already a reality as we are currently pathing
previous `gitlab-markup` version to use `python3` instead of `python2`.

We are now requiring `python3` with the gem without having to patch it.

As a consequence to also make it easy to use it in development, we've
introduced a `Pipfile` and `Pipfile.lock`, working similarly to
`Gemfile` and `Gemfile.lock`, and added documentation on how to use
them.

1 files changed, 79 insertions, 0 deletions

diff --git a/doc/development/python_guide/index.md b/doc/development/python_guide/index.md
new file mode 100644
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+++ b/doc/development/python_guide/index.md
@@ -0,0 +1,79 @@
+# Python Development Guidelines
+
+GitLab requires Python as a dependency for [reStructuredText](http://docutils.sourceforge.net/rst.html)
+markup rendering.
+
+As of GitLab 11.10, we require Python 3.
+
+## Installation
+
+There are several ways of installing python on your system. To be able to use the same version we use in production,
+we suggest you use [pyenv](https://github.com/pyenv/pyenv). It works and behave similar to its counterpart in the
+ruby world: [rbenv](https://github.com/rbenv/rbenv).
+
+### macOS
+
+To install `pyenv` on macOS, you can use [Homebrew](https://brew.sh/) with:
+
+```bash
+brew install pyenv
+```
+
+### Linux
+
+To install `pyenv` on Linux, you can run the command below:
+
+```bash
+curl https://pyenv.run | bash
+```
+
+Alternatively, you may find `pypenv` available as a system package via your distro package manager.
+
+You can read more about it in: <https://github.com/pyenv/pyenv-installer#prerequisites>.
+
+### Shell integration
+
+Pyenv installation will add required changes to Bash. If you use a different shell,
+check for any additional steps required for it.
+
+For Fish, you can install a plugin for [Fisherman](https://github.com/fisherman/fisherman):
+
+```bash
+fisher add fisherman/pyenv
+```
+
+Or for [Oh My Fish](https://github.com/oh-my-fish/oh-my-fish):
+
+```bash
+omf install pyenv
+```
+
+## Dependency management
+
+While GitLab doesn't directly contain any Python scripts, because we depend on Python to render
+[reStructuredText](http://docutils.sourceforge.net/rst.html) markup, we need to keep track on dependencies
+on the main project level, so we can run that on our development machines.
+
+Recently, an equivalent to the `Gemfile` and the [Bundler](https://bundler.io/) project has been introduced to Python:
+`Pipfile` and [Pipenv](https://pipenv.readthedocs.io/en/latest/).
+
+You will now find a `Pipfile` with the dependencies in the root folder. To install them, run:
+
+```bash
+pipenv install
+```
+
+Running this command will install both the required Python version as well as required pip dependencies.
+
+## Use instructions
+
+To run any python code under the Pipenv environment, you need to first start a `virtualenv` based on the dependencies
+of the application. With Pipenv, this is a simple as running:
+
+```bash
+pipenv shell
+```
+
+After running that command, you can run GitLab on the same shell and it will be using the Python and dependencies
+installed from the `pipenv install` command.
+