Running Skyline in a Python virtualenv

Running Skyline in a Python virtualenv is the recommended way to run Skyline. This allows for Skyline apps and all dependencies to be isolated from the system Python version and packages and allows Skyline be be run with a specific version of Python and as importantly specific versions of the dependencies packages.

The possible overhead of adding Python virtualenv functionality to any configuration management is probably worth the effort in the long run.


Use sudo appropriately for your environment wherever necessary.

HOWTO Python virtualenv Skyline


Building Python versions from the Python sources in Python virtualenv requires the following system dependencies:

  • RedHat family
yum -y install epel-release
yum -y install autoconf zlib-devel openssl-devel sqlite-devel bzip2-devel \
  gcc gcc-c++ readline-devel ncurses-devel gdbm-devel compat-readline5 \
  freetype-devel libpng-devel python-pip wget tar git
  • Debian family
apt-get -y install build-essential
apt-get -y install autoconf zlib1g-dev libssl-dev libsqlite3-dev libbz2-dev \
  libreadline6-dev libgdbm-dev libncurses5 libncurses5-dev libncursesw5 \
  libfreetype6-dev libxft-dev python-pip wget tar git


Regardless of your OS as long as you have pip installed you can install virtualenv. NOTE: if you are using a version of Python virtualenv already, this may not suit your setup.

virtualenv must be >= 15.0.1 and <16.0.0 due to some recent changes in pip, setuptools and virtualenv, see Recent changes in the pip environment section in Requirements for more details.

This is using your system pip at this point only to install virtualenv.

pip install 'virtualenv==15.2.0'

Python version


Python-2.7.14 should still work as well, but all documentation has been updated to use Python-2.7.16.

Below we use the path /opt/python_virtualenv, which you can substitute with any path you choose. We are going to use the Python-2.7.16 source and build and install an isolated Python-2.7.16, this has no effect on your system Python:


mkdir -p "${PYTHON_VIRTUALENV_DIR}/projects"

wget -q "${PYTHON_VERSION}/Python-${PYTHON_VERSION}.tgz"
tar -zxvf "Python-${PYTHON_VERSION}.tgz"

./configure --prefix=${PYTHON_VIRTUALENV_DIR}/versions/${PYTHON_VERSION}

# Optionally here if you have the time or interest you can run
# make test

make altinstall

You will now have a Python-2.7.16 environment with the Python executable: /opt/python_virtualenv/versions/2.7.16/bin/python2.7

Create a Skyline Python virtualenv

A word of warning relating to pip, setuptools and distribute if you have opted not to use the above as you have Python virtualenv already. As of virtualenv 15.0.1 the pip community adopted the new pkg_resources _markerlib package structure, which means the following in the virtualenv context:

  • distribute cannot be installed
  • pip must be >=8.1.0
  • setuptools must be >=20.2.2

Once again using Python-2.7.16:


cd "${PYTHON_VIRTUALENV_DIR}/projects"
virtualenv --python="${PYTHON_VIRTUALENV_DIR}/versions/${PYTHON_VERSION}/bin/python${PYTHON_MAJOR_VERSION}" "$PROJECT"

Make sure to add the /etc/skyline/skyline.conf file - see Installation