Source code for venv
From Get docs
Python/docs/3.7/ modules/venv
Source code for venv
"""
Virtual environment (venv) package for Python. Based on PEP 405.
Copyright (C) 2011-2014 Vinay Sajip.
Licensed to the PSF under a contributor agreement.
"""
import logging
import os
import shutil
import subprocess
import sys
import sysconfig
import types
CORE_VENV_DEPS = ('pip', 'setuptools')
logger = logging.getLogger(__name__)
[docs]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, delete the contents of the environment directory if
it already exists, before environment creation.
:param symlinks: If True, attempt to symlink rather than copy files into
virtual environment.
:param upgrade: If True, upgrade an existing virtual environment.
:param with_pip: If True, ensure pip is installed in the virtual
environment
:param prompt: Alternative terminal prefix for the environment.
:param upgrade_deps: Update the base venv modules to the latest on PyPI
"""
def __init__(self, system_site_packages=False, clear=False,
symlinks=False, upgrade=False, with_pip=False, prompt=None,
upgrade_deps=False):
self.system_site_packages = system_site_packages
self.clear = clear
self.symlinks = symlinks
self.upgrade = upgrade
self.with_pip = with_pip
if prompt == '.': # see bpo-38901
prompt = os.path.basename(os.getcwd())
self.prompt = prompt
self.upgrade_deps = upgrade_deps
[docs] 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)
# See issue 24875. We need system_site_packages to be False
# until after pip is installed.
true_system_site_packages = self.system_site_packages
self.system_site_packages = False
self.create_configuration(context)
self.setup_python(context)
if self.with_pip:
self._setup_pip(context)
if not self.upgrade:
self.setup_scripts(context)
self.post_setup(context)
if true_system_site_packages:
# We had set it to False before, now
# restore it and rewrite the configuration
self.system_site_packages = True
self.create_configuration(context)
if self.upgrade_deps:
self.upgrade_dependencies(context)
def clear_directory(self, path):
for fn in os.listdir(path):
fn = os.path.join(path, fn)
if os.path.islink(fn) or os.path.isfile(fn):
os.remove(fn)
elif os.path.isdir(fn):
shutil.rmtree(fn)
[docs] 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)
elif os.path.islink(d) or os.path.isfile(d):
raise ValueError('Unable to create directory %r' % d)
if os.path.exists(env_dir) and self.clear:
self.clear_directory(env_dir)
context = types.SimpleNamespace()
context.env_dir = env_dir
context.env_name = os.path.split(env_dir)[1]
prompt = self.prompt if self.prompt is not None else context.env_name
context.prompt = '(%s) ' % prompt
create_if_needed(env_dir)
executable = sys._base_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)
# Issue 21197: create lib64 as a symlink to lib on 64-bit non-OS X POSIX
if ((sys.maxsize > 2**32) and (os.name == 'posix') and
(sys.platform != 'darwin')):
link_path = os.path.join(env_dir, 'lib64')
if not os.path.exists(link_path): # Issue #21643
os.symlink('lib', link_path)
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
[docs] 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 self.prompt is not None:
f.write(f'prompt = {self.prompt!r}\n')
if os.name != 'nt':
def symlink_or_copy(self, src, dst, relative_symlinks_ok=False):
"""
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!
if relative_symlinks_ok:
assert os.path.dirname(src) == os.path.dirname(dst)
os.symlink(os.path.basename(src), dst)
else:
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)
else:
def symlink_or_copy(self, src, dst, relative_symlinks_ok=False):
"""
Try symlinking a file, and if that fails, fall back to copying.
"""
bad_src = os.path.lexists(src) and not os.path.exists(src)
if self.symlinks and not bad_src and not os.path.islink(dst):
try:
if relative_symlinks_ok:
assert os.path.dirname(src) == os.path.dirname(dst)
os.symlink(os.path.basename(src), dst)
else:
os.symlink(src, dst)
return
except Exception: # may need to use a more specific exception
logger.warning('Unable to symlink %r to %r', src, dst)
# On Windows, we rewrite symlinks to our base python.exe into
# copies of venvlauncher.exe
basename, ext = os.path.splitext(os.path.basename(src))
srcfn = os.path.join(os.path.dirname(__file__),
"scripts",
"nt",
basename + ext)
# Builds or venv's from builds need to remap source file
# locations, as we do not put them into Lib/venv/scripts
if sysconfig.is_python_build(True) or not os.path.isfile(srcfn):
if basename.endswith('_d'):
ext = '_d' + ext
basename = basename[:-2]
if basename == 'python':
basename = 'venvlauncher'
elif basename == 'pythonw':
basename = 'venvwlauncher'
src = os.path.join(os.path.dirname(src), basename + ext)
else:
src = srcfn
if not os.path.exists(src):
if not bad_src:
logger.warning('Unable to copy %r', src)
return
shutil.copyfile(src, dst)
[docs] 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
path = context.env_exe
copier = self.symlink_or_copy
dirname = context.python_dir
if os.name != 'nt':
copier(context.executable, path)
if not os.path.islink(path):
os.chmod(path, 0o755)
for suffix in ('python', 'python3', f'python3.{sys.version_info[1]}'):
path = os.path.join(binpath, suffix)
if not os.path.exists(path):
# Issue 18807: make copies if
# symlinks are not wanted
copier(context.env_exe, path, relative_symlinks_ok=True)
if not os.path.islink(path):
os.chmod(path, 0o755)
else:
if self.symlinks:
# For symlinking, we need a complete copy of the root directory
# If symlinks fail, you'll get unnecessary copies of files, but
# we assume that if you've opted into symlinks on Windows then
# you know what you're doing.
suffixes = [
f for f in os.listdir(dirname) if
os.path.normcase(os.path.splitext(f)[1]) in ('.exe', '.dll')
]
if sysconfig.is_python_build(True):
suffixes = [
f for f in suffixes if
os.path.normcase(f).startswith(('python', 'vcruntime'))
]
else:
suffixes = ['python.exe', 'python_d.exe', 'pythonw.exe',
'pythonw_d.exe']
for suffix in suffixes:
src = os.path.join(dirname, suffix)
if os.path.lexists(src):
copier(src, os.path.join(binpath, suffix))
if sysconfig.is_python_build(True):
# copy init.tcl
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)
if not os.path.exists(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_pip(self, context):
"""Installs or upgrades pip in a virtual environment"""
# We run ensurepip in isolated mode to avoid side effects from
# environment vars, the current directory and anything else
# intended for the global Python environment
cmd = [context.env_exe, '-Im', 'ensurepip', '--upgrade',
'--default-pip']
subprocess.check_output(cmd, stderr=subprocess.STDOUT)
[docs] 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)
[docs] 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.env_name)
text = text.replace('__VENV_PROMPT__', context.prompt)
text = text.replace('__VENV_BIN_NAME__', context.bin_name)
text = text.replace('__VENV_PYTHON__', context.env_exe)
return text
[docs] 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:
if (os.name == 'nt' and f.startswith('python')
and f.endswith(('.exe', '.pdb'))):
continue
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 not srcfile.endswith(('.exe', '.pdb')):
try:
data = data.decode('utf-8')
data = self.replace_variables(data, context)
data = data.encode('utf-8')
except UnicodeError 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, 'wb') as f:
f.write(data)
shutil.copymode(srcfile, dstfile)
def upgrade_dependencies(self, context):
logger.debug(
f'Upgrading {CORE_VENV_DEPS} packages in {context.bin_path}'
)
if sys.platform == 'win32':
python_exe = os.path.join(context.bin_path, 'python.exe')
else:
python_exe = os.path.join(context.bin_path, 'python')
cmd = [python_exe, '-m', 'pip', 'install', '--upgrade']
cmd.extend(CORE_VENV_DEPS)
subprocess.check_call(cmd)
[docs]def create(env_dir, system_site_packages=False, clear=False,
symlinks=False, with_pip=False, prompt=None, upgrade_deps=False):
"""Create a virtual environment in a directory."""
builder = EnvBuilder(system_site_packages=system_site_packages,
clear=clear, symlinks=symlinks, with_pip=with_pip,
prompt=prompt, upgrade_deps=upgrade_deps)
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
group = parser.add_mutually_exclusive_group()
group.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.')
group.add_argument('--copies', default=not use_symlinks,
action='store_false', dest='symlinks',
help='Try to use copies rather than symlinks, '
'even when symlinks are 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('--without-pip', dest='with_pip',
default=True, action='store_false',
help='Skips installing or upgrading pip in the '
'virtual environment (pip is bootstrapped '
'by default)')
parser.add_argument('--prompt',
help='Provides an alternative prompt prefix for '
'this environment.')
parser.add_argument('--upgrade-deps', default=False, action='store_true',
dest='upgrade_deps',
help='Upgrade core dependencies: {} to the latest '
'version in PyPI'.format(
' '.join(CORE_VENV_DEPS)))
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,
with_pip=options.with_pip,
prompt=options.prompt,
upgrade_deps=options.upgrade_deps)
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)
