buildouts

Buildout is a software tool for deploying Python applications by composing components, or parts, from reusable recipes. Originating in the Zope ecosystem, buildouts have been adopted by many Python projects to create repeatable, self-contained deployment environments. A buildout configuration is written in plain text and specifies the runtime requirements, the components to install, and how they are configured.

A buildout is described by a buildout.cfg file and optional companion files such as a versions section. The core concepts are parts, recipes, eggs, and versions. Parts are the defined components, each with a recipe that performs installation or configuration tasks. Recipes are small Python modules that implement the steps needed to assemble a component, such as fetching packages, configuring a web server, or generating configuration files. Eggs are Python packages that the application depends on. Versions pin specific package versions to ensure reproducible deployments.

The typical workflow is bootstrap, which prepares the buildout executable; then run buildout, which resolves dependencies, downloads eggs from indexes, and installs components into a single location, often a self-contained directory with a Python interpreter and scripts placed in bin/ (or Scripts/ on Windows). The result is a reproducible environment that can be deployed to different servers with minimal drift.

Common use cases include deploying complex Python applications with multiple components, notably Plone. Buildouts emphasize declarative configuration and extension through recipes, but can be complex to set up and maintain, and may be slower for large projects compared with more granular tooling.