PyPAC: Proxy auto-config for Python

PyPAC is a Python library for finding proxy auto-config (PAC) files and making HTTP requests that respect them. PAC files are often used in organizations that need fine-grained and centralized control of proxy settings.

PyPAC can find PAC files according to the DNS portion of the Web Proxy Auto-Discovery (WPAD) protocol. On Windows, PyPAC will automatically get the PAC file URL from the Internet Options dialog. On macOS, PyPAC will automatically get the PAC file URL from System Preferences.

PyPAC provides a subclass of a Requests Session, so you can start using it immediately, with any PAC file transparently discovered and honoured:

>>> from pypac import PACSession
>>> session = PACSession()
>>> session.get('http://example.org')
...

If a PAC file isn't found, then PACSession behaves like a regular Session.

If you're looking to add basic PAC functionality to a library that you're using, try the pac_context_for_url() context manager:

from pypac import pac_context_for_url
import boto3

with pac_context_for_url('https://example.amazonaws.com'):
    client = boto3.client('sqs')
    client.list_queues()

This sets up proxy environment variables at the start of the scope, based on any auto-discovered PAC and the given URL. pac_context_for_url() should work for any library that honours proxy environment variables.

Features

• The same Requests API that you already know and love
• Honour PAC setting from Windows Internet Options and macOS System Preferences
• Follow DNS Web Proxy Auto-Discovery protocol
• Proxy authentication pass-through
• Proxy failover and load balancing
• Generic components for adding PAC support to other code

PyPAC supports Python 2.7 and 3.5+.

Installation

Install PyPAC using pip:

$ python -m pip install pypac

Documentation

PyPAC's documentation is available at http://pypac.readthedocs.io/.