Virtual environment (venv) package for Python. Based on PEP 405.
Copyright (C) 2011-2014 Vinay Sajip.
Licensed to the PSF under a contributor agreement.
logger = logging.getLogger(__name__)
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
:param upgrade: If True, upgrade an existing virtual environment.
:param with_pip: If True, ensure pip is installed in the virtual
:param prompt: Alternative terminal prefix for the environment.
def __init__(self, system_site_packages=False, clear=False,
symlinks=False, upgrade=False, with_pip=False, prompt=None):
self.system_site_packages = system_site_packages
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)
self.setup_scripts(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)
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):
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.
if not os.path.exists(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':
libpath = os.path.join(env_dir, 'Lib', 'site-packages')
libpath = os.path.join(env_dir, 'lib',
'python%d.%d' % sys.version_info[:2],
context.inc_path = path = os.path.join(env_dir, incpath)
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)
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
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:
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')
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 os.path.islink(dst): # can't link to itself!
assert os.path.dirname(src) == os.path.dirname(dst)
os.symlink(os.path.basename(src), dst)
except Exception: # may need to use a more specific exception
logger.warning('Unable to symlink %r to %r', src, dst)
shutil.copyfile(src, dst)
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):
assert os.path.dirname(src) == os.path.dirname(dst)
os.symlink(os.path.basename(src), dst)
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__),
# 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'):
basename = 'venvlauncher'
elif basename == 'pythonw':
basename = 'venvwlauncher'
src = os.path.join(os.path.dirname(src), basename + ext)
if not os.path.exists(src):
logger.warning('Unable to copy %r', src)
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
binpath = context.bin_path
copier = self.symlink_or_copy
dirname = context.python_dir
copier(context.executable, path)
if not os.path.islink(path):
for suffix in ('python', 'python3'):
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):
# 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.
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):
os.path.normcase(f).startswith(('python', 'vcruntime'))
suffixes = ['python.exe', 'python_d.exe', 'pythonw.exe',
src = os.path.join(dirname, suffix)
copier(src, os.path.join(binpath, suffix))
if sysconfig.is_python_build(True):
for root, dirs, files in os.walk(context.python_dir):
tcldir = os.path.basename(root)
tcldir = os.path.join(context.env_dir, 'Lib', tcldir)
if not os.path.exists(tcldir):
src = os.path.join(root, 'init.tcl')
dst = os.path.join(tcldir, 'init.tcl')
shutil.copyfile(src, dst)
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',
subprocess.check_output(cmd, stderr=subprocess.STDOUT)
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
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
def replace_variables(self, text, context):
Replace variable placeholders in script text with context-specific
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
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)
def install_scripts(self, context, path):
Install scripts into the created environment from a directory.
:param context: The information for the environment creation request
: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-
binpath = context.bin_path
for root, dirs, files in os.walk(path):
if root == path: # at top-level, remove irrelevant dirs
if d not in ('common', os.name):
continue # ignore files in top level
if (os.name == 'nt' and f.startswith('python')
and f.endswith(('.exe', '.pdb'))):
srcfile = os.path.join(root, f)
suffix = root[plen:].split(os.sep)[2:]
dstdir = os.path.join(binpath, *suffix)
if not os.path.exists(dstdir):
dstfile = os.path.join(dstdir, f)
with open(srcfile, 'rb') as f:
if not srcfile.endswith(('.exe', '.pdb')):
data = data.decode('utf-8')
data = self.replace_variables(data, context)
data = data.encode('utf-8')
except UnicodeError as e:
logger.warning('unable to copy script %r, '
'may be binary: %s', srcfile, e)
with open(dstfile, 'wb') as f:
shutil.copymode(srcfile, dstfile)
def create(env_dir, system_site_packages=False, clear=False,
symlinks=False, with_pip=False, prompt=None):
"""Create a virtual environment in a directory."""
builder = EnvBuilder(system_site_packages=system_site_packages,
clear=clear, symlinks=symlinks, with_pip=with_pip,
if sys.version_info < (3, 3):
elif not hasattr(sys, 'base_prefix'):
raise ValueError('This script is only for use with Python >= 3.3')
parser = argparse.ArgumentParser(prog=__name__,
description='Creates virtual Python '
'environments in one or '
epilog='Once an environment has been '
'created, you may wish to '
'sourcing an activate script '
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.')
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 '
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 '
parser.add_argument('--clear', default=False, action='store_true',
dest='clear', help='Delete the contents of the '
'environment directory if it '
'already exists, before '
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 '
parser.add_argument('--prompt',
help='Provides an alternative prompt prefix for '
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,
symlinks=options.symlinks,
with_pip=options.with_pip,
if __name__ == '__main__':
print('Error: %s' % e, file=sys.stderr)
It is recommended that you Edit text format, this type of Fix handles quite a lot in one request
