pex 1.4.7

The PEX packaging toolchain.

PEX
===
.. image:: https://travis-ci.org/pantsbuild/pex.svg?branch=master
:target: https://travis-ci.org/pantsbuild/pex
.. image:: https://img.shields.io/pypi/l/pex.svg
:target: https://pypi.org/project/pex/
.. image:: https://img.shields.io/pypi/v/pex.svg
:target: https://pypi.org/project/pex/
.. image:: https://img.shields.io/pypi/pyversions/pex.svg
:target: https://pypi.org/project/pex/
.. image:: https://img.shields.io/pypi/wheel/pex.svg
:target: https://pypi.org/project/pex/#files

pex is a library for generating .pex (Python EXecutable) files which are
executable Python environments in the spirit of `virtualenvs <http://virtualenv.org>`_.
pex is an expansion upon the ideas outlined in
`PEP 441 <http://legacy.python.org/dev/peps/pep-0441/>`_
and makes the deployment of Python applications as simple as ``cp``. pex files may even
include multiple platform-specific Python distributions, meaning that a single pex file
can be portable across Linux and OS X.

pex files can be built using the ``pex`` tool. Build systems such as `Pants
<http://pantsbuild.org/>`_, `Buck <http://facebook.github.io/buck/>`_, and `{py}gradle <https://github.com/linkedin/pygradle>`_ also
support building .pex files directly.

Still unsure about what pex does or how it works? Watch this quick lightning
talk: `WTF is PEX? <http://www.youtube.com/watch?v=NmpnGhRwsu0>`_.

pex is licensed under the Apache2 license.


Installation
============

To install pex, simply

.. code-block:: bash

$ pip install pex

You can also build pex in a git clone using tox:

.. code-block:: bash

$ tox -e py27-package
$ cp dist/pex ~/bin

This builds a pex binary in ``dist/pex`` that can be copied onto your ``$PATH``.
The advantage to this approach is that it keeps your Python environment as empty as
possible and is more in-line with what pex does philosophically.


Simple Examples
===============

Launch an interpreter with ``requests``, ``flask`` and ``psutil`` in the environment:

.. code-block:: bash

$ pex requests flask 'psutil>2,<3'

Or instead freeze your current virtualenv via requirements.txt and execute it anywhere:

.. code-block:: bash

$ pex -r <(pip freeze) -o my_virtualenv.pex
$ deactivate
$ ./my_virtualenv.pex

Run webserver.py in an environment containing ``flask`` as a quick way to experiment:

.. code-block:: bash

$ pex flask -- webserver.py

Launch Sphinx in an ephemeral pex environment using the Sphinx entry point ``sphinx:main``:

.. code-block:: bash

$ pex sphinx -e sphinx:main -- --help

Build a standalone pex binary into ``pex.pex`` using the ``pex`` console_scripts entry point:

.. code-block:: bash

$ pex pex -c pex -o pex.pex

You can also build pex files that use a specific interpreter type:

.. code-block:: bash

$ pex pex -c pex --python=pypy -o pypy-pex.pex

Most pex options compose well with one another, so the above commands can be
mixed and matched. For a full list of options, just type ``pex --help``.


Integrating pex into your workflow
==================================

If you use tox (and you should!), a simple way to integrate pex into your
workflow is to add a packaging test environment to your ``tox.ini``:

.. code-block:: ini

[testenv:package]
deps = pex
commands = pex . -o dist/app.pex

Then ``tox -e package`` will produce a relocateable copy of your application
that you can copy to staging or production environments.


Documentation
=============

More documentation about pex, building .pex files, and how .pex files work
is available at https://pex.readthedocs.io.


Development
===========

pex uses `tox <https://testrun.org/tox/en/latest/>`_ for test and development automation. To run
the test suite, just invoke tox:

.. code-block:: bash

$ tox

If you don't have tox, you can generate a pex of tox:

.. code-block::

$ pex tox -c tox -o ~/bin/tox


Contributing
============

To contribute, follow these instructions: http://pantsbuild.org/howto_contribute.html

Release Notes
=============

1.4.7
-----

This is a hotfix release for a regression in setuptools compatibility introduced by #542.

* Fixup `PEX.demote_bootstrap`: fully unimport. (#554)
`PR #554 <https://github.com/pantsbuild/pex/pull/554>`_

1.4.6
-----

This release opens up setuptools support for more modern versions that support breaking changes in
`setup` used in the wild.

* Fix for super() usage on "old style class" ZipFile (#546)
`PR #546 <https://github.com/pantsbuild/pex/pull/546>`_

* Cleanup bootstrap dependencies before handoff. (#542)
`PR #542 <https://github.com/pantsbuild/pex/pull/542>`_

* Support -c for plat spec dists in multiplat pexes. (#545)
`PR #545 <https://github.com/pantsbuild/pex/pull/545>`_

* Support `-` when running as an interpreter. (#543)
`PR #543 <https://github.com/pantsbuild/pex/pull/543>`_
>`_ttps://github.com/pantsbuild/pex/pull/6275.

* Expand the range of supported setuptools. (#541)
`PR #541 <https://github.com/pantsbuild/pex/pull/541>`_

* Preserve perms of files copied to pex chroots. (#540)
`PR #540 <https://github.com/pantsbuild/pex/pull/540>`_

* Add more badges to README. (#535)
`PR #535 <https://github.com/pantsbuild/pex/pull/535>`_

* Fixup CHANGES PR links for 1.4.5.

1.4.5
-----

This release adds support for validating pex entrypoints at build time in addition to several bugfixes.

* Fix PEX environment setup. (#531)
`#531 <https://github.com/pantsbuild/pex/pull/531>`_

* Fix installers to be insensitive to extras iteration order. (#532)
`#532 <https://github.com/pantsbuild/pex/pull/532>`_

* Validate entry point at build time (#521)
`#521 <https://github.com/pantsbuild/pex/pull/521>`_

* Fix pex extraction perms. (#528)
`#528 <https://github.com/pantsbuild/pex/pull/528>`_

* Simplify `.travis.yml`. (#524)
`#524 <https://github.com/pantsbuild/pex/pull/524>`_

* Fix `PythonInterpreter` caching and ergonomics. (#518)
`#518 <https://github.com/pantsbuild/pex/pull/518>`_

* Add missing git dep. (#519)
`#519 <https://github.com/pantsbuild/pex/pull/519>`_

* Introduce a controlled env for pex testing. (#517)
`#517 <https://github.com/pantsbuild/pex/pull/517>`_

* Bump wheel version to latest. (#515)
`#515 <https://github.com/pantsbuild/pex/pull/515>`_

* Invoke test runner at a more granular level for pypy shard. (#513)
`#513 <https://github.com/pantsbuild/pex/pull/513>`_

1.4.4
-----

This release adds support for including sources and resources directly in a produced pex - without the need to use pants.

* Add resource / source bundling to pex cli (#507)
`#507 <https://github.com/pantsbuild/pex/pull/507>`_

1.4.3
-----

Another bugfix release for the 1.4.x series.

* Repair environmental marker platform setting. (#500)
`#500 <https://github.com/pantsbuild/pex/pull/500>`_

* Broaden abi selection for non-specified abi types. (#503)
`#503 <https://github.com/pantsbuild/pex/pull/503>`_

1.4.2
-----

This release repairs a tag matching regression for .egg dists that inadvertently went out in 1.4.1.

* Improve tag generation for EggPackage. (#493)
`#493 <https://github.com/pantsbuild/pex/pull/493>`_

1.4.1
-----

A bugfix release for 1.4.x.

* Repair abi prefixing for PyPy. (#483)
`#483 <https://github.com/pantsbuild/pex/pull/483>`_

* Repair .egg resolution for platform specific eggs. (#486)
`#486 <https://github.com/pantsbuild/pex/pull/486>`_

* Eliminate the python3.3 shard. (#488)
`#488 <https://github.com/pantsbuild/pex/pull/488>`_

1.4.0
-----

This release includes full Manylinux support, improvements to wheel resolution (including first class platform/abi tag targeting) and a handful of other improvements and bugfixes. Enjoy!

Special thanks to Dan Blanchard (@dan-blanchard) for seeding the initial PR for Manylinux support and wheel resolution improvements.

* Complete manylinux support in pex. (#480)
`#480 <https://github.com/pantsbuild/pex/pull/480>`_

* Add manylinux wheel support and fix a few bugs along the way (#316)
`#316 <https://github.com/pantsbuild/pex/pull/316>`_

* Skip failing tests on pypy shard. (#478)
`#478 <https://github.com/pantsbuild/pex/pull/478>`_

* Bump travis image to Trusty. (#476)
`#476 <https://github.com/pantsbuild/pex/pull/476>`_

* Mock PATH for problematic interpreter selection test in CI (#474)
`#474 <https://github.com/pantsbuild/pex/pull/474>`_

* Skip two failing integration tests. (#472)
`#472 <https://github.com/pantsbuild/pex/pull/472>`_

* Better error handling for missing setuptools. (#471)
`#471 <https://github.com/pantsbuild/pex/pull/471>`_

* Add tracebacks to IntegResults. (#469)
`#469 <https://github.com/pantsbuild/pex/pull/469>`_

* Fix failing tests in master (#466)
`#466 <https://github.com/pantsbuild/pex/pull/466>`_

* Repair isort-check failure in master. (#465)
`#465 <https://github.com/pantsbuild/pex/pull/465>`_

* Repair style issues in master. (#464)
`#464 <https://github.com/pantsbuild/pex/pull/464>`_

* Fixup PATH handling in travis.yml. (#462)
`#462 <https://github.com/pantsbuild/pex/pull/462>`_

1.3.2
-----

* Add blacklist handling for skipping requirements in pex resolver #457
`#457 <https://github.com/pantsbuild/pex/pull/457>`_

1.3.1
-----

This is a bugfix release for a regression that inadvertently went out in 1.3.0.

* scrub path when not inheriting (#449)
`#449 <https://github.com/pantsbuild/pex/pull/449>`_

* Fix up inherits_path tests to use new values (#450)
`#450 <https://github.com/pantsbuild/pex/pull/450>`_

1.3.0
-----

* inherit_path allows 'prefer', 'fallback', 'false' (#444)
`#444 <https://github.com/pantsbuild/pex/pull/444>`_

1.2.16
------

* Change PEX re-exec variable from ENV to os.environ (#441)
`#441 <https://github.com/pantsbuild/pex/pull/441>`_

1.2.15
------

* Bugfix for entry point targeting + integration test (#435)
`#435 <https://github.com/pantsbuild/pex/pull/435>`_

1.2.14
------

* Add interpreter constraints option and use constraints to search for compatible interpreters at exec time (#427)
`#427 <https://github.com/pantsbuild/pex/pull/427>`_

1.2.13
------

* Fix handling of pre-release option. (#424)
`#424 <https://github.com/pantsbuild/pex/pull/424>`_

* Patch sys module using pex_path from PEX-INFO metadata (#421)
`#421 <https://github.com/pantsbuild/pex/pull/421>`_

1.2.12
------

* Create --pex-path argument for pex cli and load pex path into pex-info metadata (#417)
`#417 <https://github.com/pantsbuild/pex/pull/417>`_

1.2.11
------

* Leverage `subprocess32` when available. (#411)
`#411 <https://github.com/pantsbuild/pex/pull/411>`_

* Kill support for python 2.6. (#408)
`#405 <https://github.com/pantsbuild/pex/issues/405>`_
`#408 <https://github.com/pantsbuild/pex/pull/408>`_

1.2.10
------

* Allow passing a preamble file to the CLI (#400)
`#400 <https://github.com/pantsbuild/pex/pull/400>`_

1.2.9
-----

* Add first-class support for multi-interpreter and multi-platform pex construction. (#394)
`#394 <https://github.com/pantsbuild/pex/pull/394>`_

1.2.8
-----

* Minimum setuptools version should be 20.3 (#391)
`#391 <https://github.com/pantsbuild/pex/pull/391>`_

* Improve wheel support in pex. (#388)
`#388 <https://github.com/pantsbuild/pex/pull/388>`_

1.2.7
-----

* Sort keys in PEX-INFO file so the output is deterministic. (#384)
`#384 <https://github.com/pantsbuild/pex/pull/384>`_

* Pass platform for SourceTranslator (#386)
`#386 <https://github.com/pantsbuild/pex/pull/386>`_

1.2.6
-----

* Fix for Ambiguous Resolvable bug in transitive dependency resolution (#367)
`#367 <https://github.com/pantsbuild/pex/pull/367>`_

1.2.5
-----

This release follows-up on 1.2.0 fixing bugs in the pre-release resolving code paths.

* Resolving pre-release when explicitly requested (#372)
`#374 <https://github.com/pantsbuild/pex/pull/374>`_

* Pass allow_prerelease to other iterators (Static, Caching) (#373)
`#373 <https://github.com/pantsbuild/pex/pull/373>`_

1.2.4
-----

* Fix bug in cached dependency resolution with exact resolvable. (#365)
`#365 <https://github.com/pantsbuild/pex/pull/365>`_

* Treat .pth injected paths as extras. (#370)
`#370 <https://github.com/pantsbuild/pex/pull/370>`_

1.2.3
-----

* Follow redirects on HTTP requests (#361)
`#361 <https://github.com/pantsbuild/pex/pull/361>`_

* Fix corner case in cached dependency resolution (#362)
`#362 <https://github.com/pantsbuild/pex/pull/362>`_

1.2.2
-----

* Fix CacheControl import. (#357)
`#357 <https://github.com/pantsbuild/pex/pull/357>`_

1.2.1
-----

This release is a quick fix for a bootstrapping bug that inadvertently went out in 1.2.0 (Issue
#354).

* Ensure `packaging` dependency is self-contained. (#355)
`#355 <https://github.com/pantsbuild/pex/pull/355>`_
`Fixes #354 <https://github.com/pantsbuild/pex/issues/354>`_

1.2.0
-----

This release changes pex requirement resolution behavior. Only stable requirements are resolved by
default now. The previous behavior that included pre-releases can be retained by passing `--pre` on
the pex command line or passing `allow_prereleases=True` via the API.

* Upgrade dependencies to modern version ranges. (#352)
`#352 <https://github.com/pantsbuild/pex/pull/352>`_

* Add support for controlling prerelease resolution. (#350)
`#350 <https://github.com/pantsbuild/pex/pull/350>`_
`Fixes #28 <https://github.com/pantsbuild/pex/issues/28>`_

1.1.20
------

* Add dummy flush method for clean interpreter exit with python3.6 (#343)
`#343 <https://github.com/pantsbuild/pex/pull/343>`_

1.1.19
------

* Implement --constraints in pex (#335)
`#335 <https://github.com/pantsbuild/pex/pull/335>`_

* Make sure namespace packages (e.g. virtualenvwrapper) don't break pex (#338)
`#338 <https://github.com/pantsbuild/pex/pull/338>`_

1.1.18
------

* Expose a PEX instance's path. (#332)
`#332 <https://github.com/pantsbuild/pex/pull/332>`_

* Check for scripts directory in get_script_from_egg (#328)
`#328 <https://github.com/pantsbuild/pex/pull/328>`_

1.1.17
------

* Make PEX_PATH unify pex sources, as well as requirements. (#329)
`#329 <https://github.com/pantsbuild/pex/pull/329>`_

1.1.16
------

* Adjust FileFinder import to work with Python 3.6. (#318)
`#318 <https://github.com/pantsbuild/pex/pull/318>`_

* Kill zipmanifest monkeypatching. (#322)
`#322 <https://github.com/pantsbuild/pex/pull/322>`_

* Bump setuptools range to latest. (#323)
`#323 <https://github.com/pantsbuild/pex/pull/323>`_

1.1.15
------

* Fix #309 by deduplicating output of the distribution finder. (#310)
`#310 <https://github.com/pantsbuild/pex/pull/310>`_

* Update wheel dependency to >0.26.0. (#304)
`#304 <https://github.com/pantsbuild/pex/pull/304>`_

1.1.14
------

* Repair Executor error handling for other classes of IOError/OSError. (#292)
`#292 <https://github.com/pantsbuild/pex/pull/292>`_

* Fix bdist_pex --pex-args. (#285)
`#285 <https://github.com/pantsbuild/pex/pull/285>`_

* Inherit user site with --inherit-path. (#284)
`#284 <https://github.com/pantsbuild/pex/pull/284>`_

1.1.13
------

* Repair passing of stdio kwargs to PEX.run(). (#288)
`#288 <https://github.com/pantsbuild/pex/pull/288>`_

1.1.12
------

* Fix bdist_pex interpreter cache directory. (#286)
`#286 <https://github.com/pantsbuild/pex/pull/286>`_

* Normalize and edify subprocess execution. (#255)
`#255 <https://github.com/pantsbuild/pex/pull/255>`_

* Don't ignore exit codes when using setuptools entry points. (#280)
`#280 <https://github.com/pantsbuild/pex/pull/280>`_
`Fixes #137 <https://github.com/pantsbuild/pex/issues/137>`_

1.1.11
------

* Update cache dir when bdist_pex.run is called directly.
`#278 <https://github.com/pantsbuild/pex/pull/278>`_
`Fixes #274 <https://github.com/pantsbuild/pex/issues/274>`_

1.1.10
------

* Improve failure modes for os.rename() as used in distribution caching.
`#271 <https://github.com/pantsbuild/pex/pull/271>`_
`Fixes #265 <https://github.com/pantsbuild/pex/issues/265>`_

1.1.9
-----

* Bugfix: Open setup.py in binary mode.
`#264 <https://github.com/pantsbuild/pex/pull/264>`_
`Fixes #263 <https://github.com/pantsbuild/pex/issues/263>`_

1.1.8
-----

* Bugfix: Repair a regression in `--disable-cache`.
`#261 <https://github.com/pantsbuild/pex/pull/261>`_
`Fixes #260 <https://github.com/pantsbuild/pex/issues/260>`_

1.1.7
-----

* Add README and supported python versions to PyPI description.
`#258 <https://github.com/pantsbuild/pex/pull/258>`_

* Use `open` with utf-8 support.
`#231 <https://github.com/pantsbuild/pex/pull/231>`_

* Add `--pex-root` option.
`#206 <https://github.com/pantsbuild/pex/pull/206>`_

1.1.6
-----

This release is a quick fix for a regression that inadvertently went out in 1.1.5 (Issue #243).

* Fix the ``bdist_pex`` ``setuptools`` command to work for python2.
`#246 <https://github.com/pantsbuild/pex/pull/246>`_
`Fixes #243 <https://github.com/pantsbuild/pex/issues/243>`_

* Upgrade pex dependencies on ``setuptools`` and ``wheel``.
`#244 <https://github.com/pantsbuild/pex/pull/244>`_
`Fixes #238 <https://github.com/pantsbuild/pex/issues/238>`_

1.1.5
-----

* Fix ``PEXBuilder.clone`` and thus ``bdist_pex --pex-args`` for ``--python`` and ``--python-shebang``.
`#234 <https://github.com/pantsbuild/pex/pull/234>`_
`Fixes #233 <https://github.com/pantsbuild/pex/issues/233>`_

* Fix old ``pkg_resources`` egg version normalization.
`#227 <https://github.com/pantsbuild/pex/pull/227>`_
`Fixes #226 <https://github.com/pantsbuild/pex/issues/226>`_

* Fix the ``inherit_path`` handling.
`#224 <https://github.com/pantsbuild/pex/pull/224>`_

* Fix handling of bad distribution script names when used as the pex entrypoint.
`#221 <https://github.com/pantsbuild/pex/issues/221>`_
`Fixes #220 <https://github.com/pantsbuild/pex/issues/220>`_

1.1.4
-----

This release is a quick fix for a regression that inadvertently went out in 1.1.3 (Issue #216).

* Add a test for the regression in ``FixedEggMetadata._zipinfo_name`` and revert the breaking commit.
`Fixes #216 <https://github.com/pantsbuild/pex/issues/216>`_

1.1.3
-----

This release includes an initial body of work towards Windows support, ABI tag support for CPython 2.x and a fix for version number normalization.

* Add python 2.x abi tag support.
`#214 <https://github.com/pantsbuild/pex/pull/214>`_
`Fixes #213 <https://github.com/pantsbuild/pex/issues/213>`_

* Add .idea to .gitignore.
`#205 <https://github.com/pantsbuild/pex/pull/205>`_

* Don't normalize version numbers as names.
`#204 <https://github.com/pantsbuild/pex/pull/204>`_

* More fixes for windows.
`#202 <https://github.com/pantsbuild/pex/pull/202>`_

* Fixes to get pex to work on windows.
`#198 <https://github.com/pantsbuild/pex/pull/198>`_

1.1.2
-----

* Bump setuptools & wheel version pinning.
`#194 <https://github.com/pantsbuild/pex/pull/194>`_

* Unescape html in PageParser.href_match_to_url.
`#191 <https://github.com/pantsbuild/pex/pull/191>`_

* Memoize calls to Crawler.crawl() for performance win in find-links based resolution.
`#187 <https://github.com/pantsbuild/pex/pull/187>`_

1.1.1
-----

* Fix infinite recursion when ``PEX_PYTHON`` points at a symlink.
`#182 <https://github.com/pantsbuild/pex/pull/182>`_

* Add ``/etc/pexrc`` to the list of pexrc locations to check.
`#183 <https://github.com/pantsbuild/pex/pull/183>`_

* Improve error messaging for platform constrained Untranslateable errors.
`#179 <https://github.com/pantsbuild/pex/pull/179>`_

1.1.0
-----

* Add support for ``.pexrc`` files for influencing the pex environment. See the notes `here
<https://github.com/pantsbuild/pex/blob/master/docs/buildingpex.rst#tailoring-pex-execution-at-build-time>`_.
`#128 <https://github.com/pantsbuild/pex/pull/128>`_.

* Bug fix: PEX_PROFILE_FILENAME and PEX_PROFILE_SORT were not respected.
`#154 <https://github.com/pantsbuild/pex/issues/154>`_.

* Adds the ``bdist_pex`` command to setuptools.
`#99 <https://github.com/pantsbuild/pex/issues/99>`_.

* Bug fix: We did not normalize package names in ``ResolvableSet``, so it was possible to depend on
``sphinx`` and ``Sphinx-1.4a0.tar.gz`` and get two versions build and included into the pex.
`#147 <https://github.com/pantsbuild/pex/issues/147>`_.

* Adds a pex-identifying User-Agent. `#101 <https://github.com/pantsbuild/pex/issues/101>`_.

1.0.3
-----

* Bug fix: Accommodate OSX ``Python`` python binaries. Previously the OSX python distributions shipped
with OSX, XCode and available via https://www.python.org/downloads/ could fail to be detected using
the ``PythonInterpreter`` class.
Fixes `#144 <https://github.com/pantsbuild/pex/issues/144>`_.

* Bug fix: PEX_SCRIPT failed when the script was from a not-zip-safe egg.
Original PR `#139 <https://github.com/pantsbuild/pex/pull/139>`_.

* Bug fix: ``sys.exit`` called without arguments would cause `None` to be printed on stderr since pex 1.0.1.
`#143 <https://github.com/pantsbuild/pex/pull/143>`_.

1.0.2
-----

* Bug fix: PEX-INFO values were overridden by environment ``Variables`` with default values that were
not explicitly set in the environment.
Fixes `#135 <https://github.com/pantsbuild/pex/issues/135>`_.

* Bug fix: Since `69649c1 <https://github.com/pantsbuild/pex/commit/69649c1>`_ we have been unpatching
the side-effects of ``sys.modules`` after ``PEX.execute``. This takes all modules imported during
the PEX lifecycle and sets all their attributes to ``None``. Unfortunately, ``sys.excepthook``,
``atexit`` and ``__del__`` may still try to operate using these tainted modules, causing exceptions
on interpreter teardown. This reverts just the ``sys`` unpatching so that the abovementioned
teardown hooks behave more predictably.
Fixes `#141 <https://github.com/pantsbuild/pex/issues/141>`_.

1.0.1
-----

* Allow PEXBuilder to optionally copy files into the PEX environment instead of hard-linking them.

* Allow PEXBuilder to optionally skip precompilation of .py files into .pyc files.

* Bug fix: PEXBuilder did not respect the target interpreter when compiling source to bytecode.
Fixes `#127 <https://github.com/pantsbuild/pex/issues/127>`_.

* Bug fix: Fix complex resolutions when using a cache.
Fixes: `#120 <https://github.com/pantsbuild/pex/issues/120>`_.

1.0.0
-----

The 1.0.0 release of pex introduces a few breaking changes: ``pex -r`` now takes requirements.txt files
instead of requirement specs, ``pex -s`` has now been removed since source specs are accepted as arguments,
and ``pex -p`` has been removed in favor of its alias ``pex -o``.

The pex *command line interface* now adheres to semver insofar as backwards incompatible CLI
changes will invoke a major version change. Any backwards incompatible changes to the PEX
environment variable semantics will also result in a major version change. The pex *API* adheres
to semver insofar as backwards incompatible API changes will invoke minor version changes.

For users of the PEX API, it is recommended to add minor version ranges, e.g. ``pex>=1.0,<1.1``.
For users of the PEX CLI, major version ranges such as ``pex>=1,<2`` should be sufficient.

* BREAKING CHANGE: Removes the ``-s`` option in favor of specifying directories directly as
arguments to the pex command line.

* BREAKING CHANGE: ``pex -r`` now takes requirements.txt filenames and *not* requirement
specs. Requirement specs are now passed as arguments to the pex tool. Use ``--`` to escape
command line arguments passed to interpreters spawned by pex. Implements
`#5 <https://github.com/pantsbuild/pex/issues/5>`_.

* Adds a number of flag aliases to be more compatible with pip command lines: ``--no-index``,
``-f``, ``--find-links``, ``--index-url``, ``--no-use-wheel``. Removes ``-p`` in favor of
``-o`` exclusively.

* Adds ``--python-shebang`` option to the pex tool in order to set the ``#!`` shebang to an exact
path. `#53 <https://github.com/pantsbuild/pex/issues/53>`_.

* Adds support for ``PEX_PYTHON`` environment variable which will cause the pex file to reinvoke
itself using the interpreter specified, e.g. ``PEX_PYTHON=python3.4`` or
``PEX_PYTHON=/exact/path/to/interpreter``. `#27 <https://github.com/pantsbuild/pex/issues/27>`_.

* Adds support for ``PEX_PATH`` environment variable which allows merging of PEX environments at
runtime. This can be used to inject plugins or entry_points or modules from one PEX into
another without explicitly building them together. `#30 <https://github.com/pantsbuild/pex/issues/30>`_.

* Consolidates documentation of ``PEX_`` environment variables and adds the ``--help-variables`` option
to the pex client. Partially addresses `#13 <https://github.com/pantsbuild/pex/issues/13>`_.

* Adds helper method to dump a package subdirectory onto disk from within a zipped PEX file. This
can be useful for applications that know they're running within a PEX and would prefer some
static assets dumped to disk instead of running as an unzipped PEX file.
`#12 <https://github.com/pantsbuild/pex/pull/12>`_.

* Now supports extras for static URLs and installable directories.
`#65 <https://github.com/pantsbuild/pex/issues/65>`_.

* Adds ``-m`` and ``--entry-point`` alias to the existing ``-e`` option for entry points in
the pex tool to evoke the similarity to ``python -m``.

* Adds console script support via ``-c/--script/--console-script`` and ``PEX_SCRIPT``. This allows
you to reference the named entry point instead of the exact ``module:name`` pair. Also supports
scripts defined in the ``scripts`` section of setup.py.
`#59 <https://github.com/pantsbuild/pex/issues/59>`_.

* Adds more debugging information when encountering unresolvable requirements.
`#79 <https://github.com/pantsbuild/pex/issues/79>`_.

* Bug fix: ``PEX_COVERAGE`` and ``PEX_PROFILE`` did not function correctly when SystemExit was raised.
Fixes `#81 <https://github.com/pantsbuild/pex/issues/81>`_.

* Bug fix: Fixes caching in the PEX tool since we don't cache the source distributions of installable
directories. `#24 <https://github.com/pantsbuild/pex/issues/24>`_.

0.9.0
-----

This is the last release before the 1.0.0 development branch is started.

* Change the setuptools range to >=2.2,<16 by handling EntryPoint changes as well as
being flexible on whether ``pkg_resources`` is a package or a module. Fixes
`#55 <https://github.com/pantsbuild/pex/issues/55>`_ and
`#34 <https://github.com/pantsbuild/pex/issues/34>`_.

* Adds option groups to the pex tool to make the help output slightly more readable.

* Bug fix: Make ``pip install pex`` work better by removing ``extras_requires`` on the
``console_script`` entry point. Fixes `#48 <https://github.com/pantsbuild/pex/issues/48>`_

* New feature: Adds an interpreter cache to the ``pex`` tool. If the user does not explicitly
disable the wheel feature and attempts to build a pex with wheels but does not have the wheel
package installed, pex will download it in order to make the feature work.
Implements `#47 <https://github.com/pantsbuild/pex/issues/47>`_ in order to
fix `#48 <https://github.com/pantsbuild/pex/issues/48>`_

0.8.6
-----

* Bug fix: Honor installed sys.excepthook in pex teardown.
`RB #1733 <https://rbcommons.com/s/twitter/r/1733>`_

* Bug fix: ``UrllibContext`` used ``replace`` as a keyword argument for ``bytes.decode``
but this only works on Python 3. `Pull Request #46 <https://github.com/pantsbuild/pex/pull/46>`_

0.8.5
-----

* Bug fix: Fixup string formatting in pex/bin/pex.py to support Python 2.6
`Pull Request #40 <https://github.com/pantsbuild/pex/pull/40>`_

0.8.4
-----

* Performance improvement: Speed up the best-case scenario of dependency resolution.
`RB #1685 <https://rbcommons.com/s/twitter/r/1685>`_

* Bug fix: Change from ``uuid4().get_hex()`` to ``uuid4().hex`` to maintain Python3
compatibility of pex.common.
`Pull Request #39 <https://github.com/pantsbuild/pex/pull/39>`_

* Bug fix: Actually cache the results of translation. Previously bdist translations
would be created in a temporary directory even if a cache location was specified.
`RB #1666 <https://rbcommons.com/s/twitter/r/1666>`_

* Bug fix: Support all potential abi tag permutations when determining platform
compatibility.
`Pull Request #33 <https://github.com/pantsbuild/pex/pull/33>`_

0.8.3
-----

* Performance improvement: Don't always write packages to disk if they've already been
cached. This can significantly speed up launching PEX files with a large
number of non-zip-safe dependencies.
`RB #1642 <https://rbcommons.com/s/twitter/r/1642>`_

0.8.2
-----

* Bug fix: Allow pex 0.8.x to parse pex files produced by earlier versions of
pex and twitter.common.python.

* Pin pex to setuptools prior to 9.x until we have a chance to make changes
related to PEP440 and the change of pkg_resources.py to a package.

0.8.1
-----

* Bug fix: Fix issue where it'd be possible to ``os.path.getmtime`` on a remote ``Link`` object
`Issue #29 <https://github.com/pantsbuild/pex/issues/29>`_

0.8.0
-----

* *API change*: Decouple translation from package iteration. This removes
the Obtainer construct entirely, which likely means if you're using PEX as
a library, you will need to change your code if you were doing anything
nontrivial. This adds a couple new options to ``resolve`` but simplifies
the story around how to cache packages.
`RB #785 <https://rbcommons.com/s/twitter/r/785/>`_

* Refactor http handling in pex to allow for alternate http implementations. Adds support
for `requests <https://github.com/kennethreitz/requests>`_,
improving both performance and security. For more information, read the commit notes at
`91c7f32 <https://github.com/pantsbuild/pex/commit/91c7f324085c18af714d35947b603a5f60aeb682>`_.
`RB #778 <https://rbcommons.com/s/twitter/r/778/>`_

* Improvements to API documentation throughout.

* Renamed ``Tracer`` to ``TraceLogger`` to prevent nondeterministic isort ordering.

* Refactor tox.ini to increase the number of environment combinations and improve coverage.

* Adds HTTP retry support for the RequestsContext.
`RB #1303 <https://rbcommons.com/s/twitter/r/1303/>`_

* Make pex --version correct.
`Issue #19 <https://github.com/pantsbuild/pex/issues/19>`_

* Bug fix: Fix over-aggressive sys.modules scrubbing for namespace packages. Under
certain circumstances, namespace packages in site-packages could conflict with packages
within a PEX, causing them to fail importing.
`RB #1378 <https://rbcommons.com/s/twitter/r/1378/>`_

* Bug fix: Replace uses of ``os.unsetenv(...)`` with ``del os.environ[...]``
`Pull Request #11 <https://github.com/pantsbuild/pex/pull/11>`_

* Bug fix: Scrub sys.path and sys.modules based upon both supplied path and
realpath of files and directories. Newer versions of virtualenv on Linux symlink site-packages
which caused those packages to not be removed from sys.path correctly.
`Issue #21 <https://github.com/pantsbuild/pex/issues/21>`_

* Bug fix: The pex -s option was not correctly pulling in transitive dependencies.
`Issue #22 <https://github.com/pantsbuild/pex/issues/22>`_

* Bug fix: Adds ``content`` method to HTTP contexts that does HTML content decoding, fixing
an encoding issue only experienced when using Python 3.
`Issue #10 <https://github.com/pantsbuild/pex/issues/10>`_

0.7.0
-----

* Rename ``twitter.common.python`` to ``pex`` and split out from the
`twitter/commons <http://github.com/twitter/commons>`_ repo.

0.6.0
-----

* Change the interpretation of ``-i`` (and of PyPIFetcher's pypi_base)
to match pip's ``-i``. This is useful for compatibility with devpi.

0.5.10
------

* Ensures that .egg/.whl distributions on disk have their mtime updated
even though we no longer overwrite them. This gives them a new time
lease against their ttl.

Without this change, once a distribution aged past the ttl it would
never be used again, and builds would re-create the same distributions
in tmpdirs over and over again.

0.5.9
-----

* Fixes an issue where SourceTranslator would overwrite .egg/.whl
distributions already on disk. Instead it should always check to see if
a copy already exists and reuse if there.

This ordinarily should not be a problem but the zipimporter caches
metadata by filename instead of stat/sha, so if the underlying contents
changed a runtime error would be thrown due to seemingly corrupt zip file
offsets. `RB #684 <https://rbcommons.com/s/twitter/r/684/>`_

0.5.8
-----

* Adds ``-i/--index`` option to the pex tool.

0.5.7
-----

* Adds ``twitter.common.python.pex_bootstrap`` ``bootstrap_pex_env`` function in
order to initialize a PEX environment from within a python interpreter.
(Patch contributed by @kwlzn)

* Adds stdin=,stdout=,stderr= keyword parameters to the ``PEX.run`` function.
(Patch from @benjy)

0.5.6
-----

* The crawler now defaults to not follow links for security reasons.
(Before the default behavior was to implicitly ``--follow-links`` for all
requirements.) `RB #293 <https://rbcommons.com/s/twitter/r/293/>`_

0.5.5
-----

* Improves scrubbing of site-packages from PEX environments.
`RB #289 <https://rbcommons.com/s/twitter/r/289/>`_

0.5.1 - 0.5.4
-------------

* Silences exceptions reported during interpreter teardown (the exceptions
resulting from incorrect atexit handler behavior) introduced by 0.4.3
`RB #253 <https://rbcommons.com/s/twitter/r/253/>`_
`RB #249 <https://rbcommons.com/s/twitter/r/249/>`_

* Adds ``__hash__`` to ``Link`` so that Packages are hashed correctly in
``twitter.common.python.resolver`` ``resolve``

0.5.0
-----

* Adds wheel support to ``twitter.common.python``
`RB #94 <https://rbcommons.com/s/twitter/r/94/>`_
`RB #154 <https://rbcommons.com/s/twitter/r/154/>`_
`RB #148 <https://rbcommons.com/s/twitter/r/148/>`_

0.4.3
-----

* Adds ``twitter.common.python.finders`` which are additional finders for
setuptools including:
- find eggs within a .zip
- find wheels within a directory
- find wheels within a .zip
`RB #86 <https://rbcommons.com/s/twitter/r/86/>`_

* Adds a new Package abstraction by refactoring Link into Link and Package.
`RB #92 <https://rbcommons.com/s/twitter/r/92/>`_

* Adds support for PEP425 tagging necessary for wheel support.
`RB #87 <https://rbcommons.com/s/twitter/r/87/>`_

* Improves python environment isolation by correctly scrubbing namespace
packages injected into module ``__path__`` attributes by nspkg pth files.
`RB #116 <https://rbcommons.com/s/twitter/r/116/>`_

* Adds ``twitter.common.python.resolver`` ``resolve`` method that handles
transitive dependency resolution better. This means that if the
requirement ``futures==2.1.2`` and an unqualified ``futures>=2`` is pulled in
transitively, our resolver will correctly resolve futures 2.1.2 instead
of reporting a VersionConflict if any version newer than 2.1.2 is
available. `RB #129 <https://rbcommons.com/s/twitter/r/129/>`_

* Factors all ``twitter.common.python`` test helpers into
``twitter.common.python.testing``
`RB #91 <https://rbcommons.com/s/twitter/r/91/>`_

* Bug fix: Fix ``OrderedSet`` atexit exceptions
`RB #147 <https://rbcommons.com/s/twitter/r/147/>`_

* Bug fix: Fix cross-device symlinking (patch from @benjy)

* Bug fix: Raise a ``RuntimeError`` if we fail to write ``pkg_resources`` into a .pex
`RB #115 <https://rbcommons.com/s/twitter/r/115/>`_

0.4.2
-----

* Upgrade to ``setuptools>=1``

0.4.1
-----

* ``twitter.common.python`` is no longer a namespace package

0.4.0
-----

* Kill the egg distiller. We now delegate .egg generation to bdist_egg.
`RB #55 <https://rbcommons.com/s/twitter/r/55/>`_

0.3.1
-----

* Short-circuit resolving a distribution if a local exact match is found.
`RB #47 <https://rbcommons.com/s/twitter/r/47/>`_

* Correctly patch the global ``pkg_resources`` ``WorkingSet`` for the lifetime
of the Python interpreter. `RB #52 <https://rbcommons.com/s/twitter/r/52/>`_

* Fixes a performance regression in setuptools ``build_zipmanifest``
`Setuptools Issue #154 <https://bitbucket.org/pypa/setuptools/issue/154/build_zipmanifest-results-should-be>`_
`RB #53 <https://rbcommons.com/s/twitter/r/53/>`_

0.3.0
-----

* Plumb through the ``--zip-safe``, ``--always-write-cache``, ``--ignore-errors``
and ``--inherit-path`` flags to the pex tool.

* Delete the unused ``PythonDirWrapper`` code.

* Split ``PEXEnvironment`` resolution into ``twitter.common.python.environment``
and deconflate ``WorkingSet``/``Environment`` state.

* Removes the monkeypatched zipimporter in favor of keeping all eggs
unzipped within PEX files. Refactors the PEX dependency cache in
``util.py``

* Adds interpreter detection for Jython and PyPy.

* Dependency translation errors should be made uniform.
(Patch from @johnsirois)

* Adds ``PEX_PROFILE_ENTRIES`` to limit the number of entries reported when
``PEX_PROFILE`` is enabled. (Patch from @rgs_)

* Bug fix: Several fixes to error handling in ``twitter.common.python.http``
(From Marc Abramowitz)

* Bug fix: PEX should not always assume that ``$PATH`` was available.
(Patch from @jamesbroadhead)

* Bug fix: Filename should be part of the .pex cache key or else multiple
identical versions will incorrectly resolve (Patch from @tc)

* Bug fix: Executed entry points shouldn't be forced to run in an
environment with ``__future__`` imports enabled. (Patch from
@lawson_patrick)

* Bug fix: Detect versionless egg links and fail fast. (Patch from
@johnsirois.)

* Bug fix: Handle setuptools>=2.1 correctly in the zipimport monkeypatch
(Patch from @johnsirois.)

0.2.3
-----

* Bug fix: Fix handling of Fetchers with ``file://`` urls.

0.2.2
-----

* Adds the pex tool as a standalone tool.

0.2.1
-----

* Bug fix: Bootstrapped ``twitter.common.python`` should declare ``twitter.common``
as a namespace package.

0.2.0
-----

* Make ``twitter.common.python`` fully standalone by consolidating
external dependencies within ``twitter.common.python.common``.

0.1.0
-----

* Initial published version of ``twitter.common.python``.