Environment setup for development

Checking Out a Copy of the Code

• Check out a copy of the code:

  git clone git://git.mcs.anl.gov/bcfg2.git

• Create link to src/lib:

  cd bcfg2
  ln -s src/lib Bcfg2

• Add bcfg2/src/sbin to your PATH environment variable

• Add bcfg2 to your PYTHONPATH environment variable

Using a Virtual Environment for Development

Bcfg2 is a pure Python program, and Python makes available certain tools that simplify creating isolated environments. Such environments are useful for running code under development, running code that needs to be installed without actually installing it in system locations, or running parallel, independent installations of the same packages.

One popular tool for doing this is virtualenv. The following commands will bootstrap an isolated environment where the Bcfg2 server can run. They assume you are starting from an empty directory, on a Posix-like system that has Python and the virtualenv package installed (e.g., on Debian it is available as python-virtualenv):

# Work in a scratch directory
mkdir test_env
cd test_env

# This creates the environment
virtualenv .

# "Activate" the environment. From this point forward, Python
# and its libraries will first be searched for in test_env and
# its subdirectories. When you begin a new session that should
# use this environment, re-execute this command.
. bin/activate

# The pip command is useful for installing python code from a
# variety of locations, including directly from git repositories
easy_install pip

# Install Bcfg2 from git. The -e puts the source in an editable
# git clone under the "src" dir.
pip install -e git://git.mcs.anl.gov/bcfg2.git#egg=Bcfg2

# Install a newer version of the Cheetah library, for example
pip install --upgrade cheetah

# If you want to run IPython from within the virtual
# environment, it will need to be installed locally, even if it
# is already available on the system, or else it won't find .
pip install --upgrade ipython

# Note, if you install IPython, deactivate and reactivate the
# virtualenv before attempting to use it.
deactivate
. bin/activate

Note

One caveat about this environment is that it assumes you have already installed Bcfg2’s dependencies on the system itself. Pip is capable of building packages such as lxml that include native code, but you will need to be sure its build-time prerequisites are available.

Consider using the above commands to create an isolated Bcfg2 environment in the same directory as your Bcfg2 repository. Copy your /etc/bcfg2.conf file into a local etc directory, tweak the paths as needed and you can run an independent Bcfg2 server as a non-root user. This is useful for confirming a new release of Bcfg2 and all its tools works against your current repository before upgrading.