Bootstrapping a buildout gives its own buildout script, independent of its Python environment. There are 2 reasons you might use this:

Enable automatic Buildout upgrade (or downgrade).

If the buildout script is local to the buildout, then Buildout will check for newest versions of Buildout and its dependencies that are consistent with any version pins and install any that are different, in which case, it restarts to use the new versions.

Doing automatic upgrades allows buildouts to be more independent of their environments and more repeatable.

Using a local buildout script may be necessary for a project that pins the version of Buildout itself and the pinned version is different from the version in the Python environment.

Avoid modifying the python environment.

From a philosophical point of view, Buildout has tried to be isolated from its environment, and requiring the Python environment to be modified, by installing Buildout, was inconsistent.

Before virtualenv existed, it might not have been possible to modify the environment without building Python from source.

Installing from scratch

We recommend to install buildout via pip install inside a virtualenv:

virtualenv my_buildout
cd my_buildout
bin/pip install zc.buildout

Local bootstrapping using the bootstrap command

You can use the bootstrap command of a buildout script installed in your Python environment to bootstrap a new buildout in the current directory:

buildout bootstrap

If you have any other buildouts that have local buildout scripts, you can use their buildout scripts:

/path/to/some/buildout/bin/buildout bootstrap

In this case, the buildout being bootstrapped will have the same Python environment as the buildout that was used to bootstrap it.

Bootstrapping requires a buildout.cfg, init creates one

Normally, when bootstrapping, the local directory must have a buildout.cfg file.

If you don’t have one, you can use the init command instead:

buildout init

If you know you’re going to use some packages, you can supply requirements on the command line after init:

buildout init bobo six

In which case it will generate and run a buildout that uses them. The command above would generate a buildout configuration file:

parts = py

recipe = zc.recipe.egg
interpreter = py
eggs =

This can provide an easy way to experiment with a package without adding it to your Python environment or creating a virtualenv.