A script which demonstrates how to extend Python 3.3's EnvBuilder, by installing setuptools and pip in created venvs. This functionality is not provided as an integral part of Python 3.3 because, while setuptools and pip are very popular, they are third-party packages.The script needs Python 3.3 or later; invoke it using"python pyvenvex.py -h"for all the command line options. It's basically a superset of the pyvenv script which comes as part of Python 3.3. (original) (raw)

import os

import os.path

from subprocess import Popen, PIPE

import sys

from threading import Thread

from urllib.parse import urlparse

from urllib.request import urlretrieve

import venv

class ExtendedEnvBuilder(venv.EnvBuilder):

"""

This builder installs setuptools and pip so that you can pip or

easy_install other packages into the created environment.

:param nodist: If True, setuptools and pip are not installed into the

created environment.

:param nopip: If True, pip is not installed into the created

environment.

:param progress: If setuptools or pip are installed, the progress of the

installation can be monitored by passing a progress

callable. If specified, it is called with two

arguments: a string indicating some progress, and a

context indicating where the string is coming from.

The context argument can have one of three values:

'main', indicating that it is called from virtualize()

itself, and 'stdout' and 'stderr', which are obtained

by reading lines from the output streams of a subprocess

which is used to install the app.

If a callable is not specified, default progress

information is output to sys.stderr.

"""

def __init__(self, *args, **kwargs):

self.nodist = kwargs.pop('nodist', False)

self.nopip = kwargs.pop('nopip', False)

self.progress = kwargs.pop('progress', None)

self.verbose = kwargs.pop('verbose', False)

super().__init__(*args, **kwargs)

def post_setup(self, context):

"""

Set up any packages which need to be pre-installed into the

environment being created.

:param context: The information for the environment creation request

being processed.

"""

os.environ['VIRTUAL_ENV'] = context.env_dir

if not self.nodist:

self.install_setuptools(context)

# Can't install pip without setuptools

if not self.nopip and not self.nodist:

self.install_pip(context)

def reader(self, stream, context):

"""

Read lines from a subprocess' output stream and either pass to a progress

callable (if specified) or write progress information to sys.stderr.

"""

progress = self.progress

while True:

s = stream.readline()

if not s:

break

if progress is not None:

progress(s, context)

else:

if not self.verbose:

sys.stderr.write('.')

else:

sys.stderr.write(s.decode('utf-8'))

sys.stderr.flush()

stream.close()

def install_script(self, context, name, url):

_, _, path, _, _, _ = urlparse(url)

fn = os.path.split(path)[-1]

binpath = context.bin_path

distpath = os.path.join(binpath, fn)

# Download script into the env's binaries folder

urlretrieve(url, distpath)

progress = self.progress

if self.verbose:

term = '\n'

else:

term = ''

if progress is not None:

progress('Installing %s ...%s' % (name, term), 'main')

else:

sys.stderr.write('Installing %s ...%s' % (name, term))

sys.stderr.flush()

# Install in the env

args = [context.env_exe, fn]

p = Popen(args, stdout=PIPE, stderr=PIPE, cwd=binpath)

t1 = Thread(target=self.reader, args=(p.stdout, 'stdout'))

t1.start()

t2 = Thread(target=self.reader, args=(p.stderr, 'stderr'))

t2.start()

p.wait()

t1.join()

t2.join()

if progress is not None:

progress('done.', 'main')

else:

sys.stderr.write('done.\n')

# Clean up - no longer needed

os.unlink(distpath)

def install_setuptools(self, context):

"""

Install setuptools in the environment.

:param context: The information for the environment creation request

being processed.

"""

url = 'https://bootstrap.pypa.io/ez\_setup.py'

self.install_script(context, 'setuptools', url)

# clear up the setuptools archive which gets downloaded

pred = lambda o: o.startswith('setuptools-') and o.endswith('.tar.gz')

files = filter(pred, os.listdir(context.bin_path))

for f in files:

f = os.path.join(context.bin_path, f)

os.unlink(f)

def install_pip(self, context):

"""

Install pip in the environment.

:param context: The information for the environment creation request

being processed.

"""

url = 'https://bootstrap.pypa.io/get-pip.py'

self.install_script(context, 'pip', url)

def main(args=None):

compatible = True

if sys.version_info < (3, 3):

compatible = False

elif not hasattr(sys, 'base_prefix'):

compatible = False

if not compatible:

raise ValueError('This script is only for use with '

'Python 3.3 or later')

else:

import argparse

parser = argparse.ArgumentParser(prog=__name__,

description='Creates virtual Python '

'environments in one or '

'more target '

'directories.')

parser.add_argument('dirs', metavar='ENV_DIR', nargs='+',

help='A directory to create the environment in.')

parser.add_argument('--no-setuptools', default=False,

action='store_true', dest='nodist',

help="Don't install setuptools or pip in the "

"virtual environment.")

parser.add_argument('--no-pip', default=False,

action='store_true', dest='nopip',

help="Don't install pip in the virtual "

"environment.")

parser.add_argument('--system-site-packages', default=False,

action='store_true', dest='system_site',

help='Give the virtual environment access to the '

'system site-packages dir.')

if os.name == 'nt':

use_symlinks = False

else:

use_symlinks = True

parser.add_argument('--symlinks', default=use_symlinks,

action='store_true', dest='symlinks',

help='Try to use symlinks rather than copies, '

'when symlinks are not the default for '

'the platform.')

parser.add_argument('--clear', default=False, action='store_true',

dest='clear', help='Delete the contents of the '

'environment directory if it '

'already exists, before '

'environment creation.')

parser.add_argument('--upgrade', default=False, action='store_true',

dest='upgrade', help='Upgrade the environment '

'directory to use this version '

'of Python, assuming Python '

'has been upgraded in-place.')

parser.add_argument('--verbose', default=False, action='store_true',

dest='verbose', help='Display the output '

'from the scripts which '

'install setuptools and pip.')

options = parser.parse_args(args)

if options.upgrade and options.clear:

raise ValueError('you cannot supply --upgrade and --clear together.')

builder = ExtendedEnvBuilder(system_site_packages=options.system_site,

clear=options.clear,

symlinks=options.symlinks,

upgrade=options.upgrade,

nodist=options.nodist,

nopip=options.nopip,

verbose=options.verbose)

for d in options.dirs:

builder.create(d)

if __name__ == '__main__':

rc = 1

try:

main()

rc = 0

except Exception as e:

print('Error: %s' % e, file=sys.stderr)

sys.exit(rc)