"""
Virtual environment (venv) package for Python. Based on PEP 405.
Copyright (C) 2011-2012 Vinay Sajip.
Licensed to the PSF under a contributor agreement.
usage: python -m venv [-h] [--system-site-packages] [--symlinks] [--clear]
[--upgrade]
ENV_DIR [ENV_DIR ...]
Creates virtual Python environments in one or more target directories.
positional arguments:
ENV_DIR A directory to create the environment in.
optional arguments:
-h, --help show this help message and exit
--system-site-packages
Give the virtual environment access to the system
site-packages dir.
--symlinks Attempt to symlink rather than copy.
--clear Delete the environment directory if it already exists.
If not specified and the directory exists, an error is
raised.
--upgrade Upgrade the environment directory to use this version
of Python, assuming Python has been upgraded in-place.
"""
import logging
import os
import shutil
import sys
import sysconfig
import types
logger = logging.getLogger(__name__)
class EnvBuilder:
"""
This class exists to allow virtual environment creation to be
customized. The constructor parameters determine the builder's
behaviour when called upon to create a virtual environment.
By default, the builder makes the system (global) site-packages dir
*un*available to the created environment.
If invoked using the Python -m option, the default is to use copying
on Windows platforms but symlinks elsewhere. If instantiated some
other way, the default is to *not* use symlinks.
:param system_site_packages: If True, the system (global) site-packages
dir is available to created environments.
:param clear: If True and the target directory exists, it is deleted.
Otherwise, if the target directory exists, an error is
raised.
:param symlinks: If True, attempt to symlink rather than copy files into
virtual environment.
:param upgrade: If True, upgrade an existing virtual environment.
"""
def __init__(self, system_site_packages=False, clear=False,
symlinks=False, upgrade=False):
self.system_site_packages = system_site_packages
self.clear = clear
self.symlinks = symlinks
self.upgrade = upgrade
def create(self, env_dir):
"""
Create a virtual environment in a directory.
:param env_dir: The target directory to create an environment in.
"""
env_dir = os.path.abspath(env_dir)
context = self.ensure_directories(env_dir)
self.create_configuration(context)
self.setup_python(context)
if not self.upgrade:
self.setup_scripts(context)
self.post_setup(context)
def ensure_directories(self, env_dir):
"""
Create the directories for the environment.
Returns a context object which holds paths in the environment,
for use by subsequent logic.
"""
def create_if_needed(d):
if not os.path.exists(d):
os.makedirs(d)
if os.path.exists(env_dir) and not (self.clear or self.upgrade):
raise ValueError('Directory exists: %s' % env_dir)
if os.path.exists(env_dir) and self.clear:
shutil.rmtree(env_dir)
context = types.SimpleNamespace()
context.env_dir = env_dir
context.env_name = os.path.split(env_dir)[1]
context.prompt = '(%s) ' % context.env_name
create_if_needed(env_dir)
env = os.environ
if sys.platform == 'darwin' and '__PYVENV_LAUNCHER__' in env:
executable = os.environ['__PYVENV_LAUNCHER__']
else:
executable = sys.executable
dirname, exename = os.path.split(os.path.abspath(executable))
context.executable = executable
context.python_dir = dirname
context.python_exe = exename
if sys.platform == 'win32':
binname = 'Scripts'
incpath = 'Include'
libpath = os.path.join(env_dir, 'Lib', 'site-packages')
else:
binname = 'bin'
incpath = 'include'
libpath = os.path.join(env_dir, 'lib', 'python%d.%d' % sys.version_info[:2], 'site-packages')
context.inc_path = path = os.path.join(env_dir, incpath)
create_if_needed(path)
create_if_needed(libpath)
context.bin_path = binpath = os.path.join(env_dir, binname)
context.bin_name = binname
context.env_exe = os.path.join(binpath, exename)
create_if_needed(binpath)
return context
def create_configuration(self, context):
"""
Create a configuration file indicating where the environment's Python
was copied from, and whether the system site-packages should be made
available in the environment.
:param context: The information for the environment creation request
being processed.
"""
context.cfg_path = path = os.path.join(context.env_dir, 'pyvenv.cfg')
with open(path, 'w', encoding='utf-8') as f:
f.write('home = %s\n' % context.python_dir)
if self.system_site_packages:
incl = 'true'
else:
incl = 'false'
f.write('include-system-site-packages = %s\n' % incl)
f.write('version = %d.%d.%d\n' % sys.version_info[:3])
if os.name == 'nt':
def include_binary(self, f):
if f.endswith(('.pyd', '.dll')):
result = True
else:
result = f.startswith('python') and f.endswith('.exe')
return result
def symlink_or_copy(self, src, dst):
"""
Try symlinking a file, and if that fails, fall back to copying.
"""
force_copy = not self.symlinks
if not force_copy:
try:
if not os.path.islink(dst): # can't link to itself!
os.symlink(src, dst)
except Exception: # may need to use a more specific exception
logger.warning('Unable to symlink %r to %r', src, dst)
force_copy = True
if force_copy:
shutil.copyfile(src, dst)
def setup_python(self, context):
"""
Set up a Python executable in the environment.
:param context: The information for the environment creation request
being processed.
"""
binpath = context.bin_path
exename = context.python_exe
path = context.env_exe
copier = self.symlink_or_copy
copier(context.executable, path)
dirname = context.python_dir
if os.name != 'nt':
if not os.path.islink(path):
os.chmod(path, 0o755)
for suffix in ('python', 'python3'):
path = os.path.join(binpath, suffix)
if not os.path.exists(path):
os.symlink(exename, path)
else:
subdir = 'DLLs'
include = self.include_binary
files = [f for f in os.listdir(dirname) if include(f)]
for f in files:
src = os.path.join(dirname, f)
dst = os.path.join(binpath, f)
if dst != context.env_exe: # already done, above
copier(src, dst)
dirname = os.path.join(dirname, subdir)
if os.path.isdir(dirname):
files = [f for f in os.listdir(dirname) if include(f)]
for f in files:
src = os.path.join(dirname, f)
dst = os.path.join(binpath, f)
copier(src, dst)
# copy init.tcl over
for root, dirs, files in os.walk(context.python_dir):
if 'init.tcl' in files:
tcldir = os.path.basename(root)
tcldir = os.path.join(context.env_dir, 'Lib', tcldir)
os.makedirs(tcldir)
src = os.path.join(root, 'init.tcl')
dst = os.path.join(tcldir, 'init.tcl')
shutil.copyfile(src, dst)
break
def setup_scripts(self, context):
"""
Set up scripts into the created environment from a directory.
This method installs the default scripts into the environment
being created. You can prevent the default installation by overriding
this method if you really need to, or if you need to specify
a different location for the scripts to install. By default, the
'scripts' directory in the venv package is used as the source of
scripts to install.
"""
path = os.path.abspath(os.path.dirname(__file__))
path = os.path.join(path, 'scripts')
self.install_scripts(context, path)
def post_setup(self, context):
"""
Hook for post-setup modification of the venv. Subclasses may install
additional packages or scripts here, add activation shell scripts, etc.
:param context: The information for the environment creation request
being processed.
"""
pass
def replace_variables(self, text, context):
"""
Replace variable placeholders in script text with context-specific
variables.
Return the text passed in , but with variables replaced.
:param text: The text in which to replace placeholder variables.
:param context: The information for the environment creation request
being processed.
"""
text = text.replace('__VENV_DIR__', context.env_dir)
text = text.replace('__VENV_NAME__', context.prompt)
text = text.replace('__VENV_BIN_NAME__', context.bin_name)
text = text.replace('__VENV_PYTHON__', context.env_exe)
return text
def install_scripts(self, context, path):
"""
Install scripts into the created environment from a directory.
:param context: The information for the environment creation request
being processed.
:param path: Absolute pathname of a directory containing script.
Scripts in the 'common' subdirectory of this directory,
and those in the directory named for the platform
being run on, are installed in the created environment.
Placeholder variables are replaced with environment-
specific values.
"""
binpath = context.bin_path
plen = len(path)
for root, dirs, files in os.walk(path):
if root == path: # at top-level, remove irrelevant dirs
for d in dirs[:]:
if d not in ('common', os.name):
dirs.remove(d)
continue # ignore files in top level
for f in files:
srcfile = os.path.join(root, f)
suffix = root[plen:].split(os.sep)[2:]
if not suffix:
dstdir = binpath
else:
dstdir = os.path.join(binpath, *suffix)
if not os.path.exists(dstdir):
os.makedirs(dstdir)
dstfile = os.path.join(dstdir, f)
with open(srcfile, 'rb') as f:
data = f.read()
if srcfile.endswith('.exe'):
mode = 'wb'
else:
mode = 'w'
try:
data = data.decode('utf-8')
data = self.replace_variables(data, context)
except UnicodeDecodeError as e:
data = None
logger.warning('unable to copy script %r, '
'may be binary: %s', srcfile, e)
if data is not None:
with open(dstfile, mode) as f:
f.write(data)
shutil.copymode(srcfile, dstfile)
def create(env_dir, system_site_packages=False, clear=False, symlinks=False):
"""
Create a virtual environment in a directory.
By default, makes the system (global) site-packages dir *un*available to
the created environment, and uses copying rather than symlinking for files
obtained from the source Python installation.
:param env_dir: The target directory to create an environment in.
:param system_site_packages: If True, the system (global) site-packages
dir is available to the environment.
:param clear: If True and the target directory exists, it is deleted.
Otherwise, if the target directory exists, an error is
raised.
:param symlinks: If True, attempt to symlink rather than copy files into
virtual environment.
"""
builder = EnvBuilder(system_site_packages=system_site_packages,
clear=clear, symlinks=symlinks)
builder.create(env_dir)
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')
else:
import argparse
parser = argparse.ArgumentParser(prog=__name__,
description='Creates virtual Python '
'environments in one or '
'more target '
'directories.',
epilog='Once an environment has been '
'created, you may wish to '
'activate it, e.g. by '
'sourcing an activate script '
'in its bin directory.')
parser.add_argument('dirs', metavar='ENV_DIR', nargs='+',
help='A directory to create the environment in.')
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 environment '
'directory if it already '
'exists. If not specified and '
'the directory exists, an error'
' is raised.')
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.')
options = parser.parse_args(args)
if options.upgrade and options.clear:
raise ValueError('you cannot supply --upgrade and --clear together.')
builder = EnvBuilder(system_site_packages=options.system_site,
clear=options.clear, symlinks=options.symlinks,
upgrade=options.upgrade)
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)
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