Installing
Make sure you have a recent version of pip and setuptools installed. The later needs environment marker support (setuptools>=20.6.8) and that is e.g. bundled with Python 3.4.6 but not with 3.4.4. It is probably best to do:
pip install -U pip setuptools wheel
in your environment (virtualenv, (Docker) container, etc) before installing ruamel.yaml.
ruamel.yaml itself should be installed from PyPI using:
pip install ruamel.yaml
If you want to process jinja2/YAML templates (which are not valid YAML with the default jinja2 markers), do pip install ruamel.yaml[jinja2] (you might need to quote the last argument because of the [])
There also is a commandline utility yaml available after installing:
pip install ruamel.yaml.cmd
that allows for round-trip testing/re-indenting and conversion of YAML files (JSON,INI,HTML tables)
Optional requirements
If you have the the header files for your Python executables installed then you can use the (non-roundtrip), but faster, C loader and emitter.
On Debian systems you should use:
sudo apt-get install python3-dev
you can leave out python3-dev if you don't use python3
For CentOS (7) based systems you should do:
sudo yum install python-devel