Как создать venv python

venv — Creation of virtual environments¶

The venv module supports creating lightweight “virtual environments”, each with their own independent set of Python packages installed in their site directories. A virtual environment is created on top of an existing Python installation, known as the virtual environment’s “base” Python, and may optionally be isolated from the packages in the base environment, so only those explicitly installed in the virtual environment are available.

When used from within a virtual environment, common installation tools such as pip will install Python packages into a virtual environment without needing to be told to do so explicitly.

A virtual environment is (amongst other things):

Used to contain a specific Python interpreter and software libraries and binaries which are needed to support a project (library or application). These are by default isolated from software in other virtual environments and Python interpreters and libraries installed in the operating system.
Contained in a directory, conventionally either named venv or .venv in the project directory, or under a container directory for lots of virtual environments, such as ~/.virtualenvs .
Not checked into source control systems such as Git.
Considered as disposable – it should be simple to delete and recreate it from scratch. You don’t place any project code in the environment
Not considered as movable or copyable – you just recreate the same environment in the target location.

See PEP 405 for more background on Python virtual environments.

Availability : not Emscripten, not WASI.

This module does not work or is not available on WebAssembly platforms wasm32-emscripten and wasm32-wasi . See WebAssembly platforms for more information.

Creating virtual environments¶

Creation of virtual environments is done by executing the command venv :

python -m venv /path/to/new/virtual/environment

Running this command creates the target directory (creating any parent directories that don’t exist already) and places a pyvenv.cfg file in it with a home key pointing to the Python installation from which the command was run (a common name for the target directory is .venv ). It also creates a bin (or Scripts on Windows) subdirectory containing a copy/symlink of the Python binary/binaries (as appropriate for the platform or arguments used at environment creation time). It also creates an (initially empty) lib/pythonX.Y/site-packages subdirectory (on Windows, this is Lib\site-packages ). If an existing directory is specified, it will be re-used.

Deprecated since version 3.6: pyvenv was the recommended tool for creating virtual environments for Python 3.3 and 3.4, and is deprecated in Python 3.6 .

Changed in version 3.5: The use of venv is now recommended for creating virtual environments.

On Windows, invoke the venv command as follows:

c:\>Python35\python -m venv c:\path\to\myenv

Alternatively, if you configured the PATH and PATHEXT variables for your Python installation :

c:\>python -m venv c:\path\to\myenv

The command, if run with -h , will show the available options:

usage: venv [-h] [--system-site-packages] [--symlinks | --copies] [--clear] [--upgrade] [--without-pip] [--prompt PROMPT] [--upgrade-deps] 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 Try to use symlinks rather than copies, when symlinks are not the default for the platform. --copies Try to use copies rather than symlinks, even when symlinks are the default for the platform. --clear Delete the contents of the environment directory if it already exists, before environment creation. --upgrade Upgrade the environment directory to use this version of Python, assuming Python has been upgraded in-place. --without-pip Skips installing or upgrading pip in the virtual environment (pip is bootstrapped by default) --prompt PROMPT Provides an alternative prompt prefix for this environment. --upgrade-deps Upgrade core dependencies (pip) to the latest version in PyPI Once an environment has been created, you may wish to activate it, e.g. by sourcing an activate script in its bin directory.

Changed in version 3.12: setuptools is no longer a core venv dependency.

Changed in version 3.9: Add —upgrade-deps option to upgrade pip + setuptools to the latest on PyPI

Changed in version 3.4: Installs pip by default, added the —without-pip and —copies options

Changed in version 3.4: In earlier versions, if the target directory already existed, an error was raised, unless the —clear or —upgrade option was provided.

While symlinks are supported on Windows, they are not recommended. Of particular note is that double-clicking python.exe in File Explorer will resolve the symlink eagerly and ignore the virtual environment.

On Microsoft Windows, it may be required to enable the Activate.ps1 script by setting the execution policy for the user. You can do this by issuing the following PowerShell command:

PS C:> Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser

The created pyvenv.cfg file also includes the include-system-site-packages key, set to true if venv is run with the —system-site-packages option, false otherwise.

Unless the —without-pip option is given, ensurepip will be invoked to bootstrap pip into the virtual environment.

Multiple paths can be given to venv , in which case an identical virtual environment will be created, according to the given options, at each provided path.

How venvs work¶

When a Python interpreter is running from a virtual environment, sys.prefix and sys.exec_prefix point to the directories of the virtual environment, whereas sys.base_prefix and sys.base_exec_prefix point to those of the base Python used to create the environment. It is sufficient to check sys.prefix != sys.base_prefix to determine if the current interpreter is running from a virtual environment.

A virtual environment may be “activated” using a script in its binary directory ( bin on POSIX; Scripts on Windows). This will prepend that directory to your PATH , so that running python will invoke the environment’s Python interpreter and you can run installed scripts without having to use their full path. The invocation of the activation script is platform-specific ( must be replaced by the path to the directory containing the virtual environment):

Command to activate virtual environment

PS C:\> \Scripts\Activate.ps1

New in version 3.4: fish and csh activation scripts.

New in version 3.8: PowerShell activation scripts installed under POSIX for PowerShell Core support.

You don’t specifically need to activate a virtual environment, as you can just specify the full path to that environment’s Python interpreter when invoking Python. Furthermore, all scripts installed in the environment should be runnable without activating it.

In order to achieve this, scripts installed into virtual environments have a “shebang” line which points to the environment’s Python interpreter, i.e. #!/ /bin/python . This means that the script will run with that interpreter regardless of the value of PATH . On Windows, “shebang” line processing is supported if you have the Python Launcher for Windows installed. Thus, double-clicking an installed script in a Windows Explorer window should run it with the correct interpreter without the environment needing to be activated or on the PATH .

When a virtual environment has been activated, the VIRTUAL_ENV environment variable is set to the path of the environment. Since explicitly activating a virtual environment is not required to use it, VIRTUAL_ENV cannot be relied upon to determine whether a virtual environment is being used.

Because scripts installed in environments should not expect the environment to be activated, their shebang lines contain the absolute paths to their environment’s interpreters. Because of this, environments are inherently non-portable, in the general case. You should always have a simple means of recreating an environment (for example, if you have a requirements file requirements.txt , you can invoke pip install -r requirements.txt using the environment’s pip to install all of the packages needed by the environment). If for any reason you need to move the environment to a new location, you should recreate it at the desired location and delete the one at the old location. If you move an environment because you moved a parent directory of it, you should recreate the environment in its new location. Otherwise, software installed into the environment may not work as expected.

You can deactivate a virtual environment by typing deactivate in your shell. The exact mechanism is platform-specific and is an internal implementation detail (typically, a script or shell function will be used).

API¶

The high-level method described above makes use of a simple API which provides mechanisms for third-party virtual environment creators to customize environment creation according to their needs, the EnvBuilder class.

class venv. EnvBuilder ( system_site_packages = False , clear = False , symlinks = False , upgrade = False , with_pip = False , prompt = None , upgrade_deps = False ) ¶

The EnvBuilder class accepts the following keyword arguments on instantiation:

system_site_packages – a Boolean value indicating that the system Python site-packages should be available to the environment (defaults to False ).
clear – a Boolean value which, if true, will delete the contents of any existing target directory, before creating the environment.
symlinks – a Boolean value indicating whether to attempt to symlink the Python binary rather than copying.
upgrade – a Boolean value which, if true, will upgrade an existing environment with the running Python — for use when that Python has been upgraded in-place (defaults to False ).
with_pip – a Boolean value which, if true, ensures pip is installed in the virtual environment. This uses ensurepip with the —default-pip option.
prompt – a String to be used after virtual environment is activated (defaults to None which means directory name of the environment would be used). If the special string «.» is provided, the basename of the current directory is used as the prompt.
upgrade_deps – Update the base venv modules to the latest on PyPI

Changed in version 3.4: Added the with_pip parameter

New in version 3.6: Added the prompt parameter

New in version 3.9: Added the upgrade_deps parameter

Creators of third-party virtual environment tools will be free to use the provided EnvBuilder class as a base class.

The returned env-builder is an object which has a method, create :

Create a virtual environment by specifying the target directory (absolute or relative to the current directory) which is to contain the virtual environment. The create method will either create the environment in the specified directory, or raise an appropriate exception.

The create method of the EnvBuilder class illustrates the hooks available for subclass customization:

def create(self, env_dir): """ Create a virtualized Python environment in a directory. env_dir is 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) self.setup_scripts(context) self.post_setup(context)

Creates the environment directory and all necessary subdirectories that don’t already exist, and returns a context object. This context object is just a holder for attributes (such as paths) for use by the other methods. If the EnvBuilder is created with the arg clear=True , contents of the environment directory will be cleared and then all necessary subdirectories will be recreated.

The returned context object is a types.SimpleNamespace with the following attributes:

env_dir — The location of the virtual environment. Used for __VENV_DIR__ in activation scripts (see install_scripts() ).
env_name — The name of the virtual environment. Used for __VENV_NAME__ in activation scripts (see install_scripts() ).
prompt — The prompt to be used by the activation scripts. Used for __VENV_PROMPT__ in activation scripts (see install_scripts() ).
executable — The underlying Python executable used by the virtual environment. This takes into account the case where a virtual environment is created from another virtual environment.
inc_path — The include path for the virtual environment.
lib_path — The purelib path for the virtual environment.
bin_path — The script path for the virtual environment.
bin_name — The name of the script path relative to the virtual environment location. Used for __VENV_BIN_NAME__ in activation scripts (see install_scripts() ).
env_exe — The name of the Python interpreter in the virtual environment. Used for __VENV_PYTHON__ in activation scripts (see install_scripts() ).
env_exec_cmd — The name of the Python interpreter, taking into account filesystem redirections. This can be used to run Python in the virtual environment.

Changed in version 3.12: The attribute lib_path was added to the context, and the context object was documented.

Changed in version 3.11: The venv sysconfig installation scheme is used to construct the paths of the created directories.

create_configuration ( context ) ¶

Creates the pyvenv.cfg configuration file in the environment.

Creates a copy or symlink to the Python executable in the environment. On POSIX systems, if a specific executable python3.x was used, symlinks to python and python3 will be created pointing to that executable, unless files with those names already exist.

Installs activation scripts appropriate to the platform into the virtual environment.

Upgrades the core venv dependency packages (currently pip ) in the environment. This is done by shelling out to the pip executable in the environment.

New in version 3.9.

Changed in version 3.12: setuptools is no longer a core venv dependency.

post_setup ( context ) ¶

A placeholder method which can be overridden in third party implementations to pre-install packages in the virtual environment or perform other post-creation steps.

Changed in version 3.7.2: Windows now uses redirector scripts for python[w].exe instead of copying the actual binaries. In 3.7.2 only setup_python() does nothing unless running from a build in the source tree.

Changed in version 3.7.3: Windows copies the redirector scripts as part of setup_python() instead of setup_scripts() . This was not the case in 3.7.2. When using symlinks, the original executables will be linked.

In addition, EnvBuilder provides this utility method that can be called from setup_scripts() or post_setup() in subclasses to assist in installing custom scripts into the virtual environment.

install_scripts ( context , path ) ¶

path is the path to a directory that should contain subdirectories “common”, “posix”, “nt”, each containing scripts destined for the bin directory in the environment. The contents of “common” and the directory corresponding to os.name are copied after some text replacement of placeholders:

__VENV_DIR__ is replaced with the absolute path of the environment directory.
__VENV_NAME__ is replaced with the environment name (final path segment of environment directory).
__VENV_PROMPT__ is replaced with the prompt (the environment name surrounded by parentheses and with a following space)
__VENV_BIN_NAME__ is replaced with the name of the bin directory (either bin or Scripts ).
__VENV_PYTHON__ is replaced with the absolute path of the environment’s executable.

The directories are allowed to exist (for when an existing environment is being upgraded).

There is also a module-level convenience function:

venv. create ( env_dir , system_site_packages = False , clear = False , symlinks = False , with_pip = False , prompt = None , upgrade_deps = False ) ¶

Create an EnvBuilder with the given keyword arguments, and call its create() method with the env_dir argument.

New in version 3.3.

Changed in version 3.4: Added the with_pip parameter

Changed in version 3.6: Added the prompt parameter

Changed in version 3.9: Added the upgrade_deps parameter

An example of extending EnvBuilder ¶

The following script shows how to extend EnvBuilder by implementing a subclass which installs setuptools and pip into a created virtual environment:

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 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) def post_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 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 virtual environment'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 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() 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 virtual environment. :param context: The information for the virtual 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 virtual environment. :param context: The information for the virtual environment creation request being processed. """ url = 'https://bootstrap.pypa.io/get-pip.py' self.install_script(context, 'pip', url) def main(args=None): 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 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.') 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 ' '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) 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)

This script is also available for download online.

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Геймпад как мышь windows 10

Python. Создание виртуального окружения с другой версией Python

Операционная система Windows 10. Интерпретатор python 3.9.5 Как я могу создать виртуальное окружение, к примеру с python 3.6? Пробовал и через mkvirtualenv, не получилось( Как сделать это на Windows и Linux. Спасибо!

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задан 22 янв 2022 в 17:31
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Для начала установить интерпретатор версии 3.6
22 янв 2022 в 17:32
Под Windows можно через утилиту py: py -3.6 -m venv .venv
22 янв 2022 в 17:37

3 ответа 3

Сортировка: Сброс на вариант по умолчанию

Установите ту версию python, которую хотите использовать в виртуальном пространстве. ВАЖНО! Если у вас есть основаная версия и вы не хотите конфликтов, то на моменте установки снимите галочку с опции Add python 3.6 to PATH
Далее введите (при условии, что у вас установлен python)

py -3.6 -m venv env

И вы получите виртуально пространство с python 3.6, которое будет лежать в папке env

Если вы не установите нужную версию перед созданием пространства, то получите такое сообщение

Python 3.6 not found! Installed Pythons found by py Launcher for Windows -3.9-64 * -3.8-64 Requested Python version (3.6) not installed, use -0 for available pythons

Про возможности и обзор на различные утилиты можете найти в моем ответе здесь. В том числе там сможете найти краткое описание и ссылки на pyenv

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ответ дан 22 янв 2022 в 17:59
7,722 13 13 золотых знаков 25 25 серебряных знаков 54 54 бронзовых знака

У меня к сожалению не Windows, но на MacOS это работает так:

Установить в систему (не как основной, а просто скачать и запустить установщик) python нужной версии
в консоли заходите в папку в которой хотите создать виртуальное окружение python.
пишите команду python3.x -m venv name (вместо x пишите номер версии питона после точки, а вместо name пишите название вашего окружения)
Ну вот и все! в моей системе это все что надо для создания venv ! для активации просто написать команду source name/bin/activate . Надеюсь я вам как-то помог!

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ответ дан 23 янв 2022 в 10:44
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В linux пишет что bash: python3.10.2: command not found. python3-venv стоит. В windows ориентировочно понял как сделать: 1.Скачиваешь желаемую версию, устанавливаешь в определенную папку без отметки PATH 2.Через cmd заходишь папку где установил последнею версию 3.И запускаешь venv от той версии, который хочешь, в принципе всё работает! Минус в том,что это костыль и как то неграмтно. Возможно комментарий снизу укажут на правду, используя pynev, но пока не проверял.

24 янв 2022 в 11:18

все просто потому, что надо писать в вашем случае python3.10 без .2 , и еще можно написать python3. несколько раз нажать Tab и у вас должны высветиться варианты что можно написать, выбираете из предложенного то что вам нужно, и пишите

Питон в коробке – venv в python 3.3

Наверняка, большинство из тех, кто разрабатывает или деплоит Python приложения, использует виртуальные окружения. В частности через virtualenv, написанный Ian Bicking.

Идея оказалась так хороша и распространена, что нечто похожее теперь присутствует в Python 3.3 из коробки в виде модуля venv. Он почти такой же, как virtualenv, только немного лучше.

Как это работает?

в директории с интерпретатором или уровнем выше ищется файл с именем pyvenv.cfg ;
если файл найден, в нём ищется ключ home, значение которого и будет базовой директорией;
в базовой директории идёт поиск системной библиотеки (по спец. маркеру os.py );
если что-то пошло не так – всё откатывается к захардкоженному в бинарнике значению.

Вот и вся суть venv, всё остальное уже обёртка над этим.

Как создать?

Всё очень просто, нужно вызвать через ключ -m модуль venv , либо использовать встроенный скрипт pyvenv:

pyvenv /path/to/new/venv

Скрипт создаст указанную директорию, вместе со всеми родительскими директориями, если потребуется, и построит виртуальное окружение. Это можно делать и в Windows, только вызов будет чуть более многословным:

c:\Python33\python -m venv /path/to/new/venv

При создании можно добавлять различные параметры, как, например, включение системных site-packages или использование symlink вместо копирования интерпретатора.

В отличии от virtualenv новый venv требует чтобы создаваемая директория не существовала, либо была пустой. ~~Вероятно, это сделано, чтобы не допускать конфликтов с существующими файлами.~~ Это бага в python 3.3, в 3.4 уже исправлено. (Спасибо, svetlov).

Как использовать?

Можно использовать старый добрый метод активации через bin/activate (Scripts/activate в windows):

cd /path/to/new/venv . bin/activate python3 some_script.py

А можно и не использовать, достаточно лишь вызвать интерпретатор из окружения и всё сработает автоматически:

/path/to/new/venv/bin/python3 some_script.py

Это конечно не сработает для скриптов, запускаемых напрямую через #!/usr/bin/env python3 , для них всё равно нужно будет, как и раньше, делать активацию. Решение есть – о нём чуть ниже.

Обновление

Если в вашей системе обновилась версия python, то виртуальное окружение иногда тоже нужно обновить.
Всё просто – вызываем venv аналогично созданию окружения, добавив ключ —upgrade :

pyvenv --upgrade /path/to/new/venv

Это произойдёт автоматически, если использовать symlink, но если вы хотите кроме изоляции делать фиксацию версии python и библиотек, я бы рекомендовал делать обновление вручную.

Расширение EnvBuilder

Вся работа по созданию окружения падает на класс venv.EnvBuilder , этот класс написан так, чтобы его можно было расширять.

Например, можно при инициализации окружения ставить туда distribute , pip и необходимые начальные зависимости из requirements.txt . Более сложную логику лучше оставить на совести более предназначенных для этого инструментов, типа buildout или make, но первоначальную настройку можно провести и на уровне EnvBuilder.

При создании окружения используется метод create(self, env_dir) , в исходном классе он выглядит так:

 def create(self, env_dir): 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)

Метод описывает суть всего процесса: создание директории ( ensure_directories ), конфигурацию ( create_configuration ), добавление бинарников питона ( setup_python ) и добавление скриптов активации ( setup_scripts ).

В конце вызывается хук post_setup , в который вы можете добавлять свои действия. Видно, что post_setup выполняется только при создании окружения, а при — upgrade он выполняться не будет. Это легко исправить, добавив ещё один хук:

class ImprovedEnvBuilder(venv.EnvBuilder): def create(self, env_dir): """Overwrite create method (add more hooks)""" env_dir = 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) else: self.post_upgrade(context) def post_upgrade(self, context): pass

context.bin_path — путь к директории с бинарниками и исполняемыми скриптами,
context.env_dir — путь к директории с созданным окружением,
context.env_exe — путь к бинарнику внутри окружения.

Соответственно, для запуска python скрипта внутри окружения, можно сделать:

import subprocess import venv class MyEnvBuilder(venv.EnvBuilder): def post_setup(self, context): script = '/path/to/some_script.py' subprocess.call([context.env_exe, script])

Исполняемые скрипты внутри venv

Вернёмся к проблеме с исполняемыми скриптами внутри виртуального окружения.

В virtualenv для них достаточно было указать интерпретатор через #!/usr/bin/env python3 и использовать, не забывая сделать . bin/activate . Если вас такой подход устраивал, то вы можете им продолжать пользоваться и в venv .

Есть и новый путь. Внутри EnvBuilder реализован метод install_scripts(self, context, path) , который автоматизирует копирование скриптов и бинарников в создаваемое окружение. В path необходимо передать путь к директории с вложенными поддиректориями «common», «nt», «posix» и т.д. В поддиректории, в свою очередь, положить необходимые скрипты или бинарники. В «common» скрипты для всех платформ, в «nt» – для Windows, «posix» – для Linux, Mac OS X и других posix систем.

__VENV_DIR__
__VENV_NAME__
__VENV_BIN_NAME__
__VENV_PYTHON__

Пример шаблона запускаемого python скрипта:

#!__VENV_PYTHON__ import sys import my_module if __name__ == '__main__': sys.exit(my_module.run(sys.argv))

__VENV_PYTHON__ будет заменено на полный путь к интерпретатору python в виртуальном окружении.

После установки такого скрипта через install_scripts , его можно будет запускать, без необходимости активации окружения через bin/activate.

Документация по модулю venv
PEP-405 – Python Virtual Environments
Небольшой репозиторий на github, в котором я сделал пример дополнения EnvBuilder автоматической установкой distribute, pip, списка зависимостей из requirements.txt и набором исполняемых скриптов.

12. Virtual Environments and Packages¶

Python applications will often use packages and modules that don’t come as part of the standard library. Applications will sometimes need a specific version of a library, because the application may require that a particular bug has been fixed or the application may be written using an obsolete version of the library’s interface.

This means it may not be possible for one Python installation to meet the requirements of every application. If application A needs version 1.0 of a particular module but application B needs version 2.0, then the requirements are in conflict and installing either version 1.0 or 2.0 will leave one application unable to run.

The solution for this problem is to create a virtual environment , a self-contained directory tree that contains a Python installation for a particular version of Python, plus a number of additional packages.

Different applications can then use different virtual environments. To resolve the earlier example of conflicting requirements, application A can have its own virtual environment with version 1.0 installed while application B has another virtual environment with version 2.0. If application B requires a library be upgraded to version 3.0, this will not affect application A’s environment.

12.2. Creating Virtual Environments¶

The module used to create and manage virtual environments is called venv . venv will usually install the most recent version of Python that you have available. If you have multiple versions of Python on your system, you can select a specific Python version by running python3 or whichever version you want.

To create a virtual environment, decide upon a directory where you want to place it, and run the venv module as a script with the directory path:

python -m venv tutorial-env

This will create the tutorial-env directory if it doesn’t exist, and also create directories inside it containing a copy of the Python interpreter and various supporting files.

A common directory location for a virtual environment is .venv . This name keeps the directory typically hidden in your shell and thus out of the way while giving it a name that explains why the directory exists. It also prevents clashing with .env environment variable definition files that some tooling supports.

Once you’ve created a virtual environment, you may activate it.

tutorial-env\Scripts\activate

On Unix or MacOS, run:

source tutorial-env/bin/activate

(This script is written for the bash shell. If you use the csh or fish shells, there are alternate activate.csh and activate.fish scripts you should use instead.)

Activating the virtual environment will change your shell’s prompt to show what virtual environment you’re using, and modify the environment so that running python will get you that particular version and installation of Python. For example:

$ source ~/envs/tutorial-env/bin/activate (tutorial-env) $ python Python 3.5.1 (default, May 6 2016, 10:59:36) . >>> import sys >>> sys.path ['', '/usr/local/lib/python35.zip', . '~/envs/tutorial-env/lib/python3.5/site-packages'] >>>

To deactivate a virtual environment, type:

deactivate

into the terminal.

12.3. Managing Packages with pip¶

You can install, upgrade, and remove packages using a program called pip. By default pip will install packages from the Python Package Index. You can browse the Python Package Index by going to it in your web browser.

pip has a number of subcommands: “install”, “uninstall”, “freeze”, etc. (Consult the Installing Python Modules guide for complete documentation for pip .)

You can install the latest version of a package by specifying a package’s name:

(tutorial-env) $ python -m pip install novas Collecting novas Downloading novas-3.1.1.3.tar.gz (136kB) Installing collected packages: novas Running setup.py install for novas Successfully installed novas-3.1.1.3

You can also install a specific version of a package by giving the package name followed by == and the version number:

(tutorial-env) $ python -m pip install requests==2.6.0 Collecting requests==2.6.0 Using cached requests-2.6.0-py2.py3-none-any.whl Installing collected packages: requests Successfully installed requests-2.6.0

If you re-run this command, pip will notice that the requested version is already installed and do nothing. You can supply a different version number to get that version, or you can run python -m pip install —upgrade to upgrade the package to the latest version:

(tutorial-env) $ python -m pip install --upgrade requests Collecting requests Installing collected packages: requests Found existing installation: requests 2.6.0 Uninstalling requests-2.6.0: Successfully uninstalled requests-2.6.0 Successfully installed requests-2.7.0

python -m pip uninstall followed by one or more package names will remove the packages from the virtual environment.

python -m pip show will display information about a particular package:

(tutorial-env) $ python -m pip show requests --- Metadata-Version: 2.0 Name: requests Version: 2.7.0 Summary: Python HTTP for Humans. Home-page: http://python-requests.org Author: Kenneth Reitz Author-email: me@kennethreitz.com License: Apache 2.0 Location: /Users/akuchling/envs/tutorial-env/lib/python3.4/site-packages Requires:

python -m pip list will display all of the packages installed in the virtual environment:

(tutorial-env) $ python -m pip list novas (3.1.1.3) numpy (1.9.2) pip (7.0.3) requests (2.7.0) setuptools (16.0)

python -m pip freeze will produce a similar list of the installed packages, but the output uses the format that python -m pip install expects. A common convention is to put this list in a requirements.txt file:

(tutorial-env) $ python -m pip freeze > requirements.txt (tutorial-env) $ cat requirements.txt novas==3.1.1.3 numpy==1.9.2 requests==2.7.0

The requirements.txt can then be committed to version control and shipped as part of an application. Users can then install all the necessary packages with install -r :

(tutorial-env) $ python -m pip install -r requirements.txt Collecting novas==3.1.1.3 (from -r requirements.txt (line 1)) . Collecting numpy==1.9.2 (from -r requirements.txt (line 2)) . Collecting requests==2.7.0 (from -r requirements.txt (line 3)) . Installing collected packages: novas, numpy, requests Running setup.py install for novas Successfully installed novas-3.1.1.3 numpy-1.9.2 requests-2.7.0

pip has many more options. Consult the Installing Python Modules guide for complete documentation for pip . When you’ve written a package and want to make it available on the Python Package Index, consult the Python packaging user guide.