A simple script to bootstrap setuptools and pip into a Python environment which doesn't have them.

getpip.py

#
# Copyright (C) 2013 Vinay Sajip. New BSD License.
#
import argparse
import os
import shutil
from subprocess import Popen, PIPE
import sys
import tempfile
from threading import Thread
from urllib.parse import urlparse
from urllib.request import urlretrieve

def main(args=None):
    def reader(stream, verbose):
        """
        Read lines from a subprocess' output stream and either pass to a progress
        callable (if specified) or write progress information to sys.stderr.
        """
        while True:
            s = stream.readline()
            if not s:
                break
            if not verbose:
                sys.stderr.write('.')
            else:
                sys.stderr.write(s.decode('utf-8'))
                sys.stderr.flush()
        stream.close()

    def install_script(workdir, name, url, verbose):
        _, _, path, _, _, _ = urlparse(url)
        fn = os.path.split(path)[-1]
        distpath = os.path.join(workdir, fn)
        urlretrieve(url, distpath)
        if verbose:
            term = '\n'
        else:
            term = ''
        sys.stderr.write('Installing %s ...%s' % (name, term))
        sys.stderr.flush()
        args = [sys.executable, fn]
        p = Popen(args, stdout=PIPE, stderr=PIPE, cwd=workdir)
        t1 = Thread(target=reader, args=(p.stdout, verbose))
        t1.start()
        t2 = Thread(target=reader, args=(p.stderr, verbose))
        t2.start()
        p.wait()
        t1.join()
        t2.join()
        sys.stderr.write('done.\n')

    parser = argparse.ArgumentParser(description='Bootstrap setuptools and '
                                                 'pip.')
    parser.add_argument('-v', '--verbose', default=False, action='store_true',
                        help='Display output from subcommands')
    options = parser.parse_args()
    workdir = tempfile.mkdtemp()
    try:
        try:
            import setuptools
            print('setuptools already available.')
        except ImportError:
            url = 'https://bitbucket.org/pypa/setuptools/downloads/ez_setup.py'
            install_script(workdir, 'setuptools', url, options.verbose)
        try:
            import pip
            print('pip already available.')
        except ImportError:
            url = 'https://raw.github.com/pypa/pip/master/contrib/get-pip.py'
            install_script(workdir, 'pip', url, options.verbose)
    finally:
        shutil.rmtree(workdir)

if __name__ == '__main__':
    rc = 1
    try:
        main()
        rc = 0
    except Exception as e:
        print('Error: %s' % e, file=sys.stderr)
    sys.exit(rc)