ez_setup.py

#!/usr/bin/env python
"""Bootstrap setuptools installation

To use setuptools in your package's setup.py, include this
file in the same directory and add this to the top of your setup.py::

 from ez_setup import use_setuptools
 use_setuptools()

To require a specific version of setuptools, set a download
mirror, or use an alternate download directory, simply supply
the appropriate options to ``use_setuptools()``.

This file can also be run as a script to install or upgrade setuptools.
"""
import os
import shutil
import sys
import tempfile
import zipfile
import optparse
import subprocess
import platform
import textwrap
import contextlib

from distutils import log

try:
 from site import USER_SITE
except ImportError:
 USER_SITE = None

DEFAULT_VERSION = "3.1"
DEFAULT_URL = "https://pypi.python.org/packages/source/s/setuptools/"

def _python_cmd(*args):
 """
 Return True if the command succeeded.
 """
 args = (sys.executable,) + args
 return subprocess.call(args) == 0


def _install(archive_filename, install_args=()):
 with archive_context(archive_filename):
 # installing
 log.warn('Installing Setuptools')
 if not _python_cmd('setup.py', 'install', *install_args):
 log.warn('Something went wrong during the installation.')
 log.warn('See the error message above.')
 # exitcode will be 2
 return 2


def _build_egg(egg, archive_filename, to_dir):
 with archive_context(archive_filename):
 # building an egg
 log.warn('Building a Setuptools egg in %s', to_dir)
 _python_cmd('setup.py', '-q', 'bdist_egg', '--dist-dir', to_dir)
 # returning the result
 log.warn(egg)
 if not os.path.exists(egg):
 raise IOError('Could not build the egg.')


def get_zip_class():
 """
 Supplement ZipFile class to support context manager for Python 2.6
 """
 class ContextualZipFile(zipfile.ZipFile):
 def __enter__(self):
 return self
 def __exit__(self, type, value, traceback):
 self.close
 return zipfile.ZipFile if hasattr(zipfile.ZipFile, '__exit__') else \
 ContextualZipFile


@contextlib.contextmanager
def archive_context(filename):
 # extracting the archive
 tmpdir = tempfile.mkdtemp()
 log.warn('Extracting in %s', tmpdir)
 old_wd = os.getcwd()
 try:
 os.chdir(tmpdir)
 with get_zip_class()(filename) as archive:
 archive.extractall()

 # going in the directory
 subdir = os.path.join(tmpdir, os.listdir(tmpdir)[0])
 os.chdir(subdir)
 log.warn('Now working in %s', subdir)
 yield

 finally:
 os.chdir(old_wd)
 shutil.rmtree(tmpdir)


def _do_download(version, download_base, to_dir, download_delay):
 egg = os.path.join(to_dir, 'setuptools-%s-py%d.%d.egg'
 % (version, sys.version_info[0], sys.version_info[1]))
 if not os.path.exists(egg):
 archive = download_setuptools(version, download_base,
 to_dir, download_delay)
 _build_egg(egg, archive, to_dir)
 sys.path.insert(0, egg)

 # Remove previously-imported pkg_resources if present (see
 # https://bitbucket.org/pypa/setuptools/pull-request/7/ for details).
 if 'pkg_resources' in sys.modules:
 del sys.modules['pkg_resources']

 import setuptools
 setuptools.bootstrap_install_from = egg


def use_setuptools(version=DEFAULT_VERSION, download_base=DEFAULT_URL,
 to_dir=os.curdir, download_delay=15):
 to_dir = os.path.abspath(to_dir)
 rep_modules = 'pkg_resources', 'setuptools'
 imported = set(sys.modules).intersection(rep_modules)
 try:
 import pkg_resources
 except ImportError:
 return _do_download(version, download_base, to_dir, download_delay)
 try:
 pkg_resources.require("setuptools>=" + version)
 return
 except pkg_resources.DistributionNotFound:
 return _do_download(version, download_base, to_dir, download_delay)
 except pkg_resources.VersionConflict as VC_err:
 if imported:
 msg = textwrap.dedent("""
 The required version of setuptools (>={version}) is not available,
 and can't be installed while this script is running. Please
 install a more recent version first, using
 'easy_install -U setuptools'.

 (Currently using {VC_err.args[0]!r})
 """).format(VC_err=VC_err, version=version)
 sys.stderr.write(msg)
 sys.exit(2)

 # otherwise, reload ok
 del pkg_resources, sys.modules['pkg_resources']
 return _do_download(version, download_base, to_dir, download_delay)

def _clean_check(cmd, target):
 """
 Run the command to download target. If the command fails, clean up before
 re-raising the error.
 """
 try:
 subprocess.check_call(cmd)
 except subprocess.CalledProcessError:
 if os.access(target, os.F_OK):
 os.unlink(target)
 raise

def download_file_powershell(url, target):
 """
 Download the file at url to target using Powershell (which will validate
 trust). Raise an exception if the command cannot complete.
 """
 target = os.path.abspath(target)
 cmd = [
 'powershell',
 '-Command',
 "(new-object System.Net.WebClient).DownloadFile(%(url)r, %(target)r)" % vars(),
 ]
 _clean_check(cmd, target)

def has_powershell():
 if platform.system() != 'Windows':
 return False
 cmd = ['powershell', '-Command', 'echo test']
 devnull = open(os.path.devnull, 'wb')
 try:
 try:
 subprocess.check_call(cmd, stdout=devnull, stderr=devnull)
 except:
 return False
 finally:
 devnull.close()
 return True

download_file_powershell.viable = has_powershell

def download_file_curl(url, target):
 cmd = ['curl', url, '--silent', '--output', target]
 _clean_check(cmd, target)

def has_curl():
 cmd = ['curl', '--version']
 devnull = open(os.path.devnull, 'wb')
 try:
 try:
 subprocess.check_call(cmd, stdout=devnull, stderr=devnull)
 except:
 return False
 finally:
 devnull.close()
 return True

download_file_curl.viable = has_curl

def download_file_wget(url, target):
 cmd = ['wget', url, '--quiet', '--output-document', target]
 _clean_check(cmd, target)

def has_wget():
 cmd = ['wget', '--version']
 devnull = open(os.path.devnull, 'wb')
 try:
 try:
 subprocess.check_call(cmd, stdout=devnull, stderr=devnull)
 except:
 return False
 finally:
 devnull.close()
 return True

download_file_wget.viable = has_wget

def download_file_insecure(url, target):
 """
 Use Python to download the file, even though it cannot authenticate the
 connection.
 """
 try:
 from urllib.request import urlopen
 except ImportError:
 from urllib2 import urlopen
 src = dst = None
 try:
 src = urlopen(url)
 # Read/write all in one block, so we don't create a corrupt file
 # if the download is interrupted.
 data = src.read()
 dst = open(target, "wb")
 dst.write(data)
 finally:
 if src:
 src.close()
 if dst:
 dst.close()

download_file_insecure.viable = lambda: True

def get_best_downloader():
 downloaders = [
 download_file_powershell,
 download_file_curl,
 download_file_wget,
 download_file_insecure,
 ]

 for dl in downloaders:
 if dl.viable():
 return dl

def download_setuptools(version=DEFAULT_VERSION, download_base=DEFAULT_URL,
 to_dir=os.curdir, delay=15, downloader_factory=get_best_downloader):
 """
 Download setuptools from a specified location and return its filename

 `version` should be a valid setuptools version number that is available
 as an egg for download under the `download_base` URL (which should end
 with a '/'). `to_dir` is the directory where the egg will be downloaded.
 `delay` is the number of seconds to pause before an actual download
 attempt.

 ``downloader_factory`` should be a function taking no arguments and
 returning a function for downloading a URL to a target.
 """
 # making sure we use the absolute path
 to_dir = os.path.abspath(to_dir)
 zip_name = "setuptools-%s.zip" % version
 url = download_base + zip_name
 saveto = os.path.join(to_dir, zip_name)
 if not os.path.exists(saveto): # Avoid repeated downloads
 log.warn("Downloading %s", url)
 downloader = downloader_factory()
 downloader(url, saveto)
 return os.path.realpath(saveto)

def _build_install_args(options):
 """
 Build the arguments to 'python setup.py install' on the setuptools package
 """
 return ['--user'] if options.user_install else []

def _parse_args():
 """
 Parse the command line for options
 """
 parser = optparse.OptionParser()
 parser.add_option(
 '--user', dest='user_install', action='store_true', default=False,
 help='install in user site package (requires Python 2.6 or later)')
 parser.add_option(
 '--download-base', dest='download_base', metavar="URL",
 default=DEFAULT_URL,
 help='alternative URL from where to download the setuptools package')
 parser.add_option(
 '--insecure', dest='downloader_factory', action='store_const',
 const=lambda: download_file_insecure, default=get_best_downloader,
 help='Use internal, non-validating downloader'
 )
 parser.add_option(
 '--version', help="Specify which version to download",
 default=DEFAULT_VERSION,
 )
 options, args = parser.parse_args()
 # positional arguments are ignored
 return options

def main():
 """Install or upgrade setuptools and EasyInstall"""
 options = _parse_args()
 archive = download_setuptools(
 version=options.version,
 download_base=options.download_base,
 downloader_factory=options.downloader_factory,
 )
 return _install(archive, _build_install_args(options))

if __name__ == '__main__':
 sys.exit(main())