Python标准库venv创建虚拟环境

importos
importos.path
fromsubprocessimportPopen,PIPE
importsys
fromthreadingimportThread
fromurllib.parseimporturlparse
fromurllib.requestimporturlretrieve
importvenv
classExtendedEnvBuilder(venv.EnvBuilder):
"""
    This builder installs setuptools and pip so that you can pip or
    easy_install other packages into the created virtual environment.
    :param nodist: If true, setuptools and pip are not installed into the
                   created virtual environment.
    :param nopip: If true, pip is not installed into the created
                  virtual 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)
defpost_setup(self,context):
"""
        Set up any packages which need to be pre-installed into the
        virtual environment being created.
        :param context: The information for the virtual environment
                        creation request being processed.
        """
os.environ['VIRTUAL_ENV']=context.env_dir
ifnotself.nodist:
self.install_setuptools(context)
# Can't install pip without setuptools
ifnotself.nopipandnotself.nodist:
self.install_pip(context)
defreader(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
whileTrue:
s=stream.readline()
ifnots:
break
ifprogressisnotNone:
progress(s,context)
else:
ifnotself.verbose:
sys.stderr.write('.')
else:
sys.stderr.write(s.decode('utf-8'))
sys.stderr.flush()
stream.close()
definstall_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 virtual environment's binaries folder
urlretrieve(url,distpath)
progress=self.progress
ifself.verbose:
term='\n'
else:
term=''
ifprogressisnotNone:
progress('Installing %s ...%s'%(name,term),'main')
else:
sys.stderr.write('Installing %s ...%s'%(name,term))
sys.stderr.flush()
# Install in the virtual environment
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()
ifprogressisnotNone:
progress('done.','main')
else:
sys.stderr.write('done.\n')
# Clean up - no longer needed
os.unlink(distpath)
definstall_setuptools(self,context):
"""
        Install setuptools in the virtual environment.
        :param context: The information for the virtual environment
                        creation request being processed.
        """
url='https://bitbucket.org/pypa/setuptools/downloads/ez_setup.py'
self.install_script(context,'setuptools',url)
# clear up the setuptools archive which gets downloaded
pred=lambdao:o.startswith('setuptools-')ando.endswith('.tar.gz')
files=filter(pred,os.listdir(context.bin_path))
forfinfiles:
f=os.path.join(context.bin_path,f)
os.unlink(f)
definstall_pip(self,context):
"""
        Install pip in the virtual environment.
        :param context: The information for the virtual environment
                        creation request being processed.
        """
url='https://raw.github.com/pypa/pip/master/contrib/get-pip.py'
self.install_script(context,'pip',url)
defmain(args=None):
compatible=True
ifsys.version_info<(3,3):
compatible=False
elifnothasattr(sys,'base_prefix'):
compatible=False
ifnotcompatible:
raiseValueError('This script is only for use with '
'Python 3.3 or later')
else:
importargparse
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 in which to create the
'virtual environment.')
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.')
ifos.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 '
'virtual environment '
'directory if it already '
'exists, before virtual '
'environment creation.')
parser.add_argument('--upgrade',default=False,action='store_true',
dest='upgrade',help='Upgrade the virtual '
'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)
ifoptions.upgradeandoptions.clear:
raiseValueError('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)
fordinoptions.dirs:
builder.create(d)
if__name__=='__main__':
rc=1
try:
main()
rc=0
exceptExceptionase:
print('Error: %s'%e,file=sys.stderr)
sys.exit(rc)