.. _configuration: Configuration +++++++++++++ tox configuration can be split into two categories: core and environment specific. Core settings are options that can be set once and used for all tox environments, while environment options are applied to the given tox environment only. Discovery and file types ------------------------ With regards to the configuration format, at the moment we support the following formats: - `INI `_. - `TOML `_. Out of box tox supports five configuration locations prioritized in the following order: 1. ``tox.ini`` (INI), 2. ``setup.cfg`` (INI), 3. ``pyproject.toml`` with the ``tool.tox`` table, having ``legacy_tox_ini`` key (containing INI), 4. Native ``pyproject.toml`` under the ``tool.tox`` table (TOML), 5. ``tox.toml`` (TOML). Historically, the INI format was created first, and TOML was added in 2024. The TOML format generally is more robust, however is less powerful and more verbose. You should use TOML unless you need some of the more advanced features that TOML does not support (such as conditional factors, generative environments to name a few -- however, PRs to add support for these in TOML is welcome). .. _tox-ini: ``tox.ini`` ~~~~~~~~~~~ This configuration file uses: - ``tox`` section to host core configuration, - ``testenv:{env_name}`` section to host environment configuration, - ``testenv`` section as base configuration for run environments (fallback location for missing values for a test/run environment), - ``pkgenv`` section as base configuration for package environments (fallback location for missing values for a package environment). For example: .. code-block:: ini [tox] min_version = 4.20 env_list = 3.13 3.12 type [testenv] deps = pytest commands = pytest tests [testenv:type] deps = mypy commands = mypy src ``setup.cfg`` ~~~~~~~~~~~~~ This configuration file uses: - ``tox:tox`` section to host core configuration, - ``testenv:{env_name}`` section to host environment configuration, - ``testenv`` section as base configuration for run environments (fallback location for missing values for a test/run environment), - ``pkgenv`` section as base configuration for package environments (fallback location for missing values for a package environment). .. code-block:: ini [tox:tox] min_version = 4.0 env_list = 3.13 3.12 type [testenv] deps = pytest commands = pytest tests [testenv:type] deps = mypy commands = mypy src ``pyproject.toml`` - INI ~~~~~~~~~~~~~~~~~~~~~~~~ This configuration file is equivalent to :ref:`tox.ini ` format, with the difference that the text is stored instead inside the ``pyproject.toml`` file under the ``tool.tox`` table and ``legacy_tox_ini`` key: .. code-block:: toml [tool.tox] legacy_tox_ini = """ [tox] min_version = 4.0 env_list = py310 py39 type [testenv] deps = pytest commands = pytest tests [testenv:type] deps = mypy commands = mypy src """ .. _pyproject-toml-native: ``pyproject.toml`` - native ~~~~~~~~~~~~~~~~~~~~~~~~~~~ We support native TOML configuration via the ``pyproject.toml`` files ``tool.tox`` table. This configuration file uses: - ``tool.tox`` table to host core configuration, - ``tool.tox.env.{env_name}`` table to host environment configuration, - ``tool.tox.env_run_base`` table as base configuration for run environments (fallback location for missing values for a test/run environment), - ``tool.tox.env_pkg_base`` table as base configuration for package environments (fallback location for missing values for a package environment). .. code-block:: toml [tool.tox] requires = ["tox>=4.19"] env_list = ["3.13", "3.12", "type"] [tool.tox.env_run_base] description = "Run test under {base_python}" commands = [["pytest"]] [tool.tox.env.type] description = "run type check on code base" deps = ["mypy==1.11.2", "types-cachetools>=5.5.0.20240820", "types-chardet>=5.0.4.6"] commands = [["mypy", "src{/}tox"], ["mypy", "tests"]] ``tox.toml`` ~~~~~~~~~~~~ This configuration file is equivalent to :ref:`pyproject.toml - native ` with the difference that it lives in a separate dedicated files and accordingly the ``tool.tox`` sub-table is no longer required. For example: .. code-block:: toml requires = ["tox>=4.19"] env_list = ["3.13", "3.12", "type"] [env_run_base] description = "Run test under {base_python}" commands = [["pytest"]] [env.type] description = "run type check on code base" deps = ["mypy==1.11.2", "types-cachetools>=5.5.0.20240820", "types-chardet>=5.0.4.6"] commands = [["mypy", "src{/}tox"], ["mypy", "tests"]] .. _conf-core: Core ---- The following options are set in the ``[tox]`` section of ``tox.ini`` or the ``[tox:tox]`` section of ``setup.cfg``. .. conf:: :keys: requires :default: :version_added: 3.2.0 Specify a list of :pep:`508` compliant dependencies that must be satisfied in the Python environment hosting tox when running the tox command. If any of these dependencies are not satisfied will automatically create a provisioned tox environment that does not have this issue, and run the tox command within that environment. See :ref:`provision_tox_env` for more details. .. tab:: TOML .. code-block:: toml [tool.tox.pyproject] requires = [ "tox>=4", "virtualenv>20.2", ] .. tab:: INI .. code-block:: ini [tox] requires = tox>=4 virtualenv>20.2 .. conf:: :keys: min_version, minversion :default: A string to define the minimal tox version required to run. If the host's tox version is less than this, it will automatically create a provisioned tox environment that satisfies this requirement. See :ref:`provision_tox_env` for more details. .. conf:: :keys: provision_tox_env :default: .tox :version_added: 3.8.0 Name of the tox environment used to provision a valid tox run environment. .. versionchanged:: 3.23.0 When tox is invoked with the ``--no-provision`` flag, the provision won't be attempted, tox will fail instead. .. conf:: :keys: env_list, envlist :default: A list of environments to run by default (when the user does not specify anything during the invocation). .. versionchanged:: 3.4.0 Which tox environments are run during the tox invocation can be further filtered via the operating system environment variable ``TOX_SKIP_ENV`` regular expression (e.g. ``py27.*`` means **don't** evaluate environments that start with the key ``py27``). Skipped environments will be logged at level two verbosity level. .. conf:: :keys: skip_missing_interpreters :default: config :version_added: 1.7.2 Setting this to ``true`` will force ``tox`` to return success even if some of the specified environments were missing. This is useful for some CI systems or when running on a developer box, where you might only have a subset of all your supported interpreters installed but don't want to mark the build as failed because of it. As expected, the command line switch always overrides this setting if passed on the invocation. Setting it to ``config`` means that the value is read from the config file. .. conf:: :keys: tox_root, toxinidir The root directory for the tox project (where the configuration file is found). .. conf:: :keys: work_dir, toxworkdir :default: {tox_root}/.tox Directory for tox to generate its environments into, will be created if it does not exist. .. conf:: :keys: temp_dir :default: {work_dir}/.tmp Directory where to put tox temporary files. For example: we create a hard link (if possible, otherwise new copy) in this directory for the project package. This ensures tox works correctly when having parallel runs (as each session will have its own copy of the project package - e.g. the source distribution). .. conf:: :keys: no_package, skipsdist :default: false Flag indicating to perform the packaging operation or not. Set it to ``true`` when using tox for an application, instead of a library. .. conf:: :keys: package_env, isolated_build_env :default: .pkg :version_added: 3.3.0 Default name of the virtual environment used to create a source distribution from the source tree. .. conf:: :keys: package_root, setupdir :default: {tox_root} Indicates where the packaging root file exists (historically setup.py file or pyproject.toml now). .. conf:: :keys: labels :default: A mapping of label names to environments it applies too. For example: .. tab:: TOML .. code-block:: toml [tool.pyproject] labels = { test = ["3.13", "3.12"], static = ["ruff", "mypy"] } .. tab:: INI .. code-block:: ini [tox] labels = test = 3.13, 3.12 static = ruff, mypy .. conf:: :keys: on_platform :constant: A constant holding the platform of the tox runtime environment. Python language core options ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. conf:: :keys: ignore_base_python_conflict, ignore_basepython_conflict :default: True .. versionadded:: 3.1.0 tox allows setting the Python version for an environment via the :ref:`base_python` setting. If that's not set tox can set a default value from the environment name (e.g. ``py310`` implies Python 3.10). Matching up the Python version with the environment name has became expected at this point, leading to surprises when some configs don't do so. To help with sanity of users, an error will be raised whenever the environment name version does not match up with this expectation. Furthermore, we allow hard enforcing this rule by setting this flag to ``true``. In such cases we ignore the :ref:`base_python` and instead always use the base Python implied from the Python name. This allows you to configure :ref:`base_python` in the :ref:`base` section without affecting environments that have implied base Python versions. .. _conf-testenv: tox environment --------------- These are configuration for the tox environments (either packaging or run type). Base options ~~~~~~~~~~~~ .. conf:: :keys: envname, env_name :constant: The name of the tox environment. .. conf:: :keys: env_dir, envdir :default: {work_dir}/{env_name} :version_added: 1.5 Directory assigned to the tox environment. If not absolute it would be treated as relative to :ref:`tox_root`. .. conf:: :keys: env_tmp_dir, envtmpdir :default: {work_dir}/{env_name}/tmp A folder that is always reset at the start of the run. .. conf:: :keys: env_log_dir, envlogdir :default: {work_dir}/{env_name}/log A folder containing log files about tox runs. It's always reset at the start of the run. Currently contains every process invocation in the format of ``-.log``, and details the execution request (command, environment variables, current working directory, etc.) and its outcome (exit code and standard output/error content). .. conf:: :keys: platform Run on platforms that match this regular expression (empty means any platform). If a non-empty expression is defined and does not match against the ``sys.platform`` string the entire test environment will be skipped and none of the commands will be executed. Running ``tox -e `` will run commands for a particular platform and skip the rest. .. conf:: :keys: pass_env, passenv :default: Environment variables to pass on to the tox environment. The values are evaluated as UNIX shell-style wildcards, see `fnmatch `_ If a specified environment variable doesn't exist in the tox invocation environment it is ignored. The list of environment variable names is not case sensitive, for example: passing ``A`` or ``a`` will pass through both ``A`` and ``a``. Some variables are always passed through to ensure the basic functionality of standard library functions or tooling like pip. This is also not case sensitive on all platforms except Windows. .. list-table:: Environment Variables per Operating System :widths: 25 25 25 25 :header-rows: 1 * - Environment Variable - Linux - MacOS - Windows * - https_proxy - ✅ - ✅ - ✅ * - http_proxy - ✅ - ✅ - ✅ * - no_proxy - ✅ - ✅ - ✅ * - LANG - ✅ - ✅ - ✅ * - LANGUAGE - ✅ - ✅ - ✅ * - CURL_CA_BUNDLE - ✅ - ✅ - ✅ * - SSL_CERT_FILE - ✅ - ✅ - ✅ * - CC - ✅ - ✅ - ✅ * - CFLAGS - ✅ - ✅ - ✅ * - CCSHARED - ✅ - ✅ - ✅ * - CXX - ✅ - ✅ - ✅ * - CPPFLAGS - ✅ - ✅ - ✅ * - LD_LIBRARY_PATH - ✅ - ✅ - ✅ * - LDFLAGS - ✅ - ✅ - ✅ * - HOME - ✅ - ✅ - ✅ * - FORCE_COLOR - ✅ - ✅ - ✅ * - NO_COLOR - ✅ - ✅ - ✅ * - TMPDIR - ✅ - ✅ - ❌ * - TEMP - ❌ - ❌ - ✅ * - TMP - ❌ - ❌ - ✅ * - USERPROFILE - ❌ - ❌ - ✅ * - PATHEXT - ❌ - ❌ - ✅ * - MSYSTEM - ❌ - ❌ - ✅ * - WINDIR - ❌ - ❌ - ✅ * - APPDATA - ❌ - ❌ - ✅ * - PROGRAMDATA - ❌ - ❌ - ✅ * - PROGRAMFILES(x86) - ❌ - ❌ - ✅ * - SYSTEMDRIVE - ❌ - ❌ - ✅ * - SYSTEMROOT - ❌ - ❌ - ✅ * - COMSPEC - ❌ - ❌ - ✅ * - PROCESSOR_ARCHITECTURE - ❌ - ❌ - ✅ * - NUMBER_OF_PROCESSORS - ❌ - ❌ - ✅ * - PIP_* - ✅ - ✅ - ✅ * - VIRTUALENV_* - ✅ - ✅ - ✅ More environment variable-related information can be found in :ref:`environment variable substitutions`. .. conf:: :keys: set_env, setenv A dictionary of environment variables to set when running commands in the tox environment. Lines starting with a ``file|`` prefix define the location of environment file. .. note:: Environment files are processed using the following rules: - blank lines are ignored, - lines starting with the ``#`` character are ignored, - each line is in KEY=VALUE format; both the key and the value are stripped, - there is no special handling of quotation marks, they are part of the key or value. More environment variable-related information can be found in :ref:`environment variable substitutions`. .. conf:: :keys: parallel_show_output :default: False :version_added: 3.7 If set to ``True`` the content of the output will always be shown when running in parallel mode. .. conf:: :keys: recreate :default: False Always recreate virtual environment if this option is true, otherwise leave it up to tox. .. conf:: :keys: allowlist_externals :default: Each line specifies a command name (in glob-style pattern format) which can be used in the commands section even if it's located outside of the tox environment. For example: if you use the unix *rm* command for running tests you can list ``allowlist_externals=rm`` or ``allowlist_externals=/usr/bin/rm``. If you want to allow all external commands you can use ``allowlist_externals=*`` which will match all commands (not recommended). .. conf:: :keys: labels :default: :ref_suffix: env A list of labels to apply for this environment. For example: .. tab:: TOML .. code-block:: toml [tool.pyproject.env_run_base] labels = ["test", "core"] [tool.pyproject.env.flake8] labels = ["mypy"] .. tab:: INI .. code-block:: ini [testenv] labels = test, core [testenv:flake8] labels = mypy Execute ~~~~~~~ .. conf:: :keys: suicide_timeout :default: 0.0 :version_added: 3.15.2 When an interrupt is sent via Ctrl+C or the tox process is killed with a SIGTERM, a SIGINT is sent to all foreground processes. The :ref:`suicide_timeout` gives the running process time to cleanup and exit before receiving (in some cases, a duplicate) SIGINT from tox. .. conf:: :keys: interrupt_timeout :default: 0.3 :version_added: 3.15 When tox is interrupted, it propagates the signal to the child process after :ref:`suicide_timeout` seconds. If the process still hasn't exited after :ref:`interrupt_timeout` seconds, its sends a SIGTERM. .. conf:: :keys: terminate_timeout :default: 0.2 :version_added: 3.15 When tox is interrupted, after waiting :ref:`interrupt_timeout` seconds, it propagates the signal to the child process, waits :ref:`interrupt_timeout` seconds, sends it a SIGTERM, waits :ref:`terminate_timeout` seconds, and sends it a SIGKILL if it hasn't exited. Run ~~~ .. conf:: :keys: base :default: testenv :version_added: 4.0.0 Inherit missing keys from these sections. .. conf:: :keys: runner :default: :version_added: 4.0.0 The tox execute used to evaluate this environment. Defaults to Python virtual environments, however may be overwritten by plugins. .. conf:: :keys: description :default: A short description of the environment, this will be used to explain the environment to the user upon listing environments. .. conf:: :keys: depends :default: tox environments that this environment depends on (must be run after those). .. warning:: ``depends`` does not pull in dependencies into the run target, for example if you select ``py310,py39,coverage`` via the ``-e`` tox will only run those three (even if ``coverage`` may specify as ``depends`` other targets too - such as ``py310, py39, py38``). This is solely meant to specify dependencies and order in between a target run set. .. conf:: :keys: commands_pre :default: :version_added: 3.4 Commands to run before running the :ref:`commands`. All evaluation and configuration logic applies from :ref:`commands`. .. conf:: :keys: commands :default: The commands to be called for testing. Only execute if :ref:`commands_pre` succeed. Each line is interpreted as one command; however a command can be split over multiple lines by ending the line with the ``\`` character. Commands will execute one by one in sequential fashion until one of them fails (their exit code is non-zero) or all of them succeed. The exit code of a command may be ignored (meaning they are always considered successful) by prefixing the command with a dash (``-``) - this is similar to how ``make`` recipe lines work. The outcome of the environment is considered successful only if all commands (these + setup + teardown) succeeded (exit code ignored via the ``-`` or success exit code value of zero). .. note:: The virtual environment binary path (see :ref:`env_bin_dir`) is prepended to the ``PATH`` environment variable, meaning commands will first try to resolve to an executable from within the virtual environment, and only after that outside of it. Therefore ``python`` translates as the virtual environments ``python`` (having the same runtime version as the :ref:`base_python`), and ``pip`` translates as the virtual environments ``pip``. .. note:: ``shlex`` POSIX-mode quoting rules are used to split the command line into arguments on all supported platforms as of tox 4.4.0. The backslash ``\`` character can be used to escape quotes, whitespace, itself, and other characters (except on Windows, where a backslash in a path will not be interpreted as an escape). Unescaped single quote will disable the backslash escape until closed by another unescaped single quote. For more details, please see :doc:`shlex parsing rules `. .. note:: Inline scripts can be used, however note these are discovered from the project root directory, and is not influenced by :ref:`change_dir` (this only affects the runtime current working directory). To make this behavior explicit we recommend that you make inline scripts absolute paths by prepending ``{tox_root}``, instead of ``path/to/my_script`` prefer ``{tox_root}{/}path{/}to{/}my_script``. If your inline script is platform dependent refer to :ref:`platform-specification` on how to select different script per platform. .. conf:: :keys: commands_post :default: Commands to run after running the :ref:`commands`. Execute regardless of the outcome of both :ref:`commands` and :ref:`commands_pre`. All evaluation and configuration logic applies from :ref:`commands`. .. conf:: :keys: change_dir, changedir :default: {tox_root} Change to this working directory when executing the test command. If the directory does not exist yet, it will be created (required for Windows to be able to execute any command). .. conf:: :keys: args_are_paths :default: False Treat positional arguments passed to tox as file system paths and - if they exist on the filesystem and are in relative format - rewrite them according to the current and :ref:`change_dir` working directory. This handles automatically transforming relative paths specified on the CLI to relative paths respective of the commands executing directory. .. conf:: :keys: ignore_errors :default: False When executing the commands keep going even if a sub-command exits with non-zero exit code. The overall status will be "commands failed", i.e. tox will exit non-zero in case any command failed. It may be helpful to note that this setting is analogous to the ``-k`` or ``--keep-going`` option of GNU Make. .. conf:: :keys: ignore_outcome :default: False If set to true a failing result of this test environment will not make tox fail (instead just warn). .. conf:: :keys: skip_install :default: False :version_added: 1.9 Skip installation of the package. This can be used when you need the virtualenv management but do not want to install the current package into that environment. .. conf:: :keys: package_env :default: {package_env} :version_added: 4.0.0 :ref_suffix: env Name of the virtual environment used to create a source distribution from the source tree for this environment. .. conf:: :keys: package_tox_env_type :version_added: 4.0.0 :default: virtualenv-pep-517 tox package type used to package. .. _python-options: Python options ~~~~~~~~~~~~~~ .. conf:: :keys: base_python, basepython :default: <{env_name} python factor> or Name or path to a Python interpreter which will be used for creating the virtual environment, first one found wins. This determines in practice the Python for what we'll create a virtual isolated environment. Use this to specify the Python version for a tox environment. If not specified, the virtual environments factors (e.g. name part) will be used to automatically set one. For example, ``py310`` means ``python3.10``, ``py3`` means ``python3`` and ``py`` means ``python``. If the name does not match this pattern the same Python version tox is installed into will be used. .. versionchanged:: 3.1 After resolving this value if the interpreter reports back a different version number than implied from the name a warning will be printed by default. However, if :ref:`ignore_basepython_conflict` is set, the value is ignored and we force the :ref:`base_python` implied from the factor name. .. note:: Leaving this unset will cause an error if the package under test has a different Python requires than tox itself and tox is installed into a Python that's not supported by the package. For example, if your package requires Python 3.10 or later, and you install tox in Python 3.9, when you run a tox environment that has left this unspecified tox will use Python 3.9 to build and install your package which will fail given it requires 3.10. .. conf:: :keys: env_site_packages_dir, envsitepackagesdir :constant: The Python environments site package - where packages are installed (the purelib folder path). .. conf:: :keys: env_bin_dir, envbindir :constant: The binary folder where console/gui scripts are generated during installation. .. conf:: :keys: env_python, envpython :constant: The Python executable from within the tox environment. Python run ~~~~~~~~~~ .. conf:: :keys: deps :default: Name of the Python dependencies. Installed into the environment prior to project after environment creation, but before package installation. All installer commands are executed using the :ref:`tox_root` as the current working directory. Each value must be one of: - a Python dependency as specified by :pep:`440`, - a `requirement file `_ when the value starts with ``-r`` (followed by a file path), - a `constraint file `_ when the value starts with ``-c`` (followed by a file path). For example: .. tab:: TOML .. code-block:: toml [tool.pyproject.env_run_base] deps = [ "pytest>=8", "-r requirements.txt", "-c constraints.txt", ] .. tab:: INI .. code-block:: ini [testenv] deps = pytest>=7,<8 -r requirements.txt -c constraints.txt .. conf:: :keys: use_develop, usedevelop :default: false :version_added: 1.6 Install the current package in development mode using :pep:`660`. This means that the package will be installed in-place and editable. .. note:: ``package = editable`` is the preferred way to enable development/editable mode. See the details in :ref:`package`. .. note:: PEP-660 introduced a standardized way of installing a package in development mode, providing the same effect as if ``pip install -e`` was used. .. conf:: :keys: package :version_added: 4.0 When option can be one of ``wheel``, ``sdist``, ``editable``, ``editable-legacy``, ``skip``, or ``external``. If :ref:`use_develop` is set this becomes a constant of ``editable``. If :ref:`skip_install` is set this becomes a constant of ``skip``. .. conf:: :keys: wheel_build_env :version_added: 4.0 :default: - If :ref:`package` is set to ``wheel`` this will be the tox Python environment in which the wheel will be built. The value is generated to be unique per Python flavor and version, and prefixed with :ref:`package_env` value. This is to ensure the target interpreter and the generated wheel will be compatible. If you have a wheel that can be reused across multiple Python versions set this value to the same across them (to avoid building a new wheel for each one of them). .. conf:: :keys: extras :version_added: 2.4 :default: A list of "extras" from the package to be installed. For example, ``extras = testing`` is equivalent to ``[testing]`` in a ``pip install`` command. .. _external-package-builder: External package builder ~~~~~~~~~~~~~~~~~~~~~~~~ tox supports operating with externally built packages. External packages might be provided in two ways: - explicitly via the :ref:`--installpkg ` CLI argument, - setting the :ref:`package` to ``external`` and using a tox packaging environment named ``_external`` (see :ref:`package_env`) to build the package. The tox packaging environment takes all configuration flags of a :ref:`python environment `, plus the following: .. conf:: :keys: deps :default: :ref_suffix: external Name of the Python dependencies as specified by :pep:`440`. Installed into the environment prior running the build commands. All installer commands are executed using the :ref:`tox_root` as the current working directory. .. conf:: :keys: commands :default: :ref_suffix: external Commands to run that will build the package. If any command fails the packaging operation is considered failed and will fail all environments using that package. .. conf:: :keys: ignore_errors :default: False :ref_suffix: external When executing the commands keep going even if a sub-command exits with non-zero exit code. The overall status will be "commands failed", i.e. tox will exit non-zero in case any command failed. It may be helpful to note that this setting is analogous to the ``-k`` or ``--keep-going`` option of GNU Make. .. conf:: :keys: change_dir, changedir :default: {tox_root} :ref_suffix: external Change to this working directory when executing the package build command. If the directory does not exist yet, it will be created (required for Windows to be able to execute any command). .. conf:: :keys: package_glob :default: {envtmpdir}{/}dist{/}* A glob that should match the wheel/sdist file to install. If no file or multiple files is matched the packaging operation is considered failed and will raise an error. Python virtual environment ~~~~~~~~~~~~~~~~~~~~~~~~~~ .. conf:: :keys: system_site_packages, sitepackages :default: False Create virtual environments that also have access to globally installed packages. Note the default value may be overwritten by the ``VIRTUALENV_SYSTEM_SITE_PACKAGES`` environment variable. .. warning:: In cases where a command line tool is also installed globally you have to make sure that you use the tool installed in the virtualenv by using ``python -m `` (if supported by the tool) or ``{env_bin_dir}/``. If you forget to do that you will get an error. .. conf:: :keys: always_copy, alwayscopy :default: False Force virtualenv to always copy rather than symlink. Note the default value may be overwritten by the ``VIRTUALENV_COPIES`` or ``VIRTUALENV_ALWAYS_COPY`` (in that order) environment variables. This is useful for situations where hardlinks don't work (e.g. running in VMS with Windows guests). .. conf:: :keys: download :version_added: 3.10 :default: False True if you want virtualenv to upgrade pip/wheel/setuptools to the latest version. Note the default value may be overwritten by the ``VIRTUALENV_DOWNLOAD`` environment variable. If (and only if) you want to choose a specific version (not necessarily the latest) then you can add ``VIRTUALENV_PIP=20.3.3`` (and similar) to your :ref:`set_env`. Python virtual environment packaging ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. conf:: :keys: meta_dir :version_added: 4.0.0 :default: {env_dir}/.meta Directory where to put the project metadata files. .. conf:: :keys: pkg_dir :version_added: 4.0.0 :default: {env_dir}/.dist Directory where to put project packages. .. conf:: :keys: config_settings_get_requires_for_build_sdist :version_added: 4.11 Config settings (``dict[str, str]``) passed to the ``get_requires_for_build_sdist`` backend API endpoint. .. conf:: :keys: config_settings_build_sdist :version_added: 4.11 Config settings (``dict[str, str]``) passed to the ``build_sdist`` backend API endpoint. .. conf:: :keys: config_settings_get_requires_for_build_wheel :version_added: 4.11 Config settings (``dict[str, str]``) passed to the ``get_requires_for_build_wheel`` backend API endpoint. .. conf:: :keys: config_settings_prepare_metadata_for_build_wheel :version_added: 4.11 Config settings (``dict[str, str]``) passed to the ``prepare_metadata_for_build_wheel`` backend API endpoint. .. conf:: :keys: config_settings_build_wheel :version_added: 4.11 Config settings (``dict[str, str]``) passed to the ``build_wheel`` backend API endpoint. .. conf:: :keys: config_settings_get_requires_for_build_editable :version_added: 4.11 Config settings (``dict[str, str]``) passed to the ``get_requires_for_build_editable`` backend API endpoint. .. conf:: :keys: config_settings_prepare_metadata_for_build_editable :version_added: 4.11 Config settings (``dict[str, str]``) passed to the ``prepare_metadata_for_build_editable`` backend API endpoint. .. conf:: :keys: config_settings_build_editable :version_added: 4.11 Config settings (``dict[str, str]``) passed to the ``build_editable`` backend API endpoint. .. conf:: :keys: fresh_subprocess :version_added: 4.14.0 :default: True if build backend is setuptools otherwise False A flag controlling if each call to the build backend should be done in a fresh subprocess or not (especially older build backends such as ``setuptools`` might require this to discover newly provisioned dependencies). Pip installer ~~~~~~~~~~~~~ .. conf:: :keys: install_command :default: python -I -m pip install {opts} {packages} :version_added: 1.6 Determines the command used for installing packages into the virtual environment; both the package under test and its dependencies (defined with :ref:`deps`). Must contain the substitution key ``{packages}`` which will be replaced by the package(s) to install. You should also accept ``{opts}`` -- it will contain index server options such as ``--pre`` (configured as ``pip_pre``). .. note:: You can also provide arbitrary commands to the ``install_command``. Please take care that these commands can be executed on the supported operating systems. When executing shell scripts we recommend to not specify the script directly but instead pass it to the appropriate shell as argument (e.g. prefer ``bash script.sh`` over ``script.sh``). .. conf:: :keys: list_dependencies_command :default: python -m pip freeze --all :version_added: 2.4 The ``list_dependencies_command`` setting is used for listing the packages installed into the virtual environment. This command will be executed only if executing on Continuous Integrations is detected (for example set environment variable ``CI=1``) or if journal is active. .. conf:: :keys: pip_pre :default: false :version_added: 1.9 If ``true``, adds ``--pre`` to the ``opts`` passed to :ref:`install_command`. This will cause it to install the latest available pre-release of any dependencies without a specified version. If ``false``, pip will only install final releases of unpinned dependencies. .. conf:: :keys: constrain_package_deps :default: false :version_added: 4.4.0 If ``constrain_package_deps`` is true, then tox will create and use ``{env_dir}{/}constraints.txt`` when installing package dependencies during ``install_package_deps`` stage. When this value is set to false, any conflicting package dependencies will override explicit dependencies and constraints passed to ``deps``. .. conf:: :keys: use_frozen_constraints :default: false :version_added: 4.4.0 When ``use_frozen_constraints`` is true, then tox will use the ``list_dependencies_command`` to enumerate package versions in order to create ``{env_dir}{/}constraints.txt``. Otherwise the package specifications explicitly listed under ``deps`` (or in requirements / constraints files referenced in ``deps``) will be used as the constraints. If ``constrain_package_deps`` is false, then this setting has no effect. User configuration ------------------ tox allows creation of user level config-file to modify default values of the CLI commands. It is located in the OS-specific user config directory under ``tox/config.ini`` path, see ``tox --help`` output for exact location. It can be changed via ``TOX_USER_CONFIG_FILE`` environment variable. Example configuration: .. code-block:: ini [tox] skip_missing_interpreters = true Set CLI flags via environment variables --------------------------------------- All configuration can be overridden via environment variables too, the naming convention here is ``TOX_