Warehouse codebase

Warehouse uses the Pyramid web framework, the SQLAlchemy ORM, and Postgres for its database. Warehouse’s front end uses Jinja2 templates.

The production deployment for Warehouse is deployed using Cabotage, which manages Docker containers deployed via Kubernetes.

In the development environment, we use several Docker containers orchestrated by Docker Compose to manage running the containers and the connections between them.

Since Warehouse was built on top of an existing database (for legacy PyPI) and developers had to fit our ORM to the existing tables, some of the code in the ORM may not look like code from the SQLAlchemy documentation. There are some places where joins are done using name-based logic instead of a foreign key (but this may change in the future).

Warehouse also uses hybrid URL traversal and dispatch. Using factory classes, resources are provided directly to the views based on the URL pattern. This method of handling URLs may be unfamiliar to developers used to other web frameworks, such as Django or Flask. This article has a helpful discussion of the differences between URL dispatch and traversal in Pyramid.

Usage assumptions and concepts

See PyPI help and the glossary section of UI principles to understand projects, releases, packages, maintainers, authors, and owners.

Warehouse is specifically the codebase for the official Python Package Index, and thus focuses on architecture and features for PyPI and Test PyPI. People and groups who want to run their own package indexes usually use other tools, like devpi.

Warehouse serves three main classes of users:

  1. People who are not logged in. This accounts for the majority of browser traffic and all API download traffic.
  2. Owners/maintainers of one or more projects. This accounts for almost all writes. A user must create and use a PyPI account to maintain or own a project, and there is no particular functionality available to a logged-in user other than to manage projects they own/maintain. As of March 2018, PyPI had about 270,000 users, and Test PyPI had about 30,000 users.
  3. PyPI application administrators, e.g., Ernest W. Durbin III, Dustin Ingram, and Donald Stufft, who add classifiers, ban spam/malware projects, help users with account recovery, and so on. There are under ten such admins.

Since reads are much more common than writes (much more goes out than goes in), we try to cache as much as possible. This is a big reason that, although we have supported localization in the past, we currently don’t.

File and directory structure

The top-level directory of the Warehouse repo contains files including:

  • LICENSE
  • CONTRIBUTING.rst (the contribution guide)
  • README.rst
  • requirements.txt for the Warehouse virtual environment
  • Dockerfile: creates the Docker containers that Warehouse runs in
  • docker-compose.yml file configures Docker Compose
  • setup.cfg for test configuration
  • Makefile: commands to spin up Docker Compose and the Docker containers, run the linter and other tests, etc.
  • files associated with Warehouse’s front end, e.g., Gulpfile.babel.js

Directories within the repository:

Historical context & deprecations

For the history of Python packaging and distribution, see the PyPA history page.

From the early 2000s till April 2018, the legacy PyPI codebase, not Warehouse, powered PyPI. Warehouse deliberately does not provide some features that users may be used to from the legacy site, such as: