exxo

Only Linux x86_64 supported for now

Build your Python package into a portable one-file binary and deploy it
just by copying it to target machine. The binary links to libc only and
doesn't require Python to be installed on the machine. Exxo was created
with DevOps professionals in mind, but the target audience may become
larger as project matures.

Exxo uses the excellent
PyRun project and
zipapp library. The
target binary is simply a pyrun binary with zipped application
concatenated at the end. This simple design was chosen in hope it proves
to be the most portable one (PyRun already works on most major
platforms). There's also an assumption that over time zipapps become
more popular and more essential packages will become zip safe.

In order for exxo to be practical, PyRun and CPython were patched in the
following ways:

• zipimport supports loading C extensions (otherwise too many pip
  libraries would be useless)
• zipimport is capable of loading code from __pycache__ if Python 3
  is used
• original PyRun comes with few C modules distributed separately (with
  notable examples for multiprocessing or ctypes); exxo's PyRun on
  the other hand is a truly one file binary with all modules included
  (at the cost of portability loss, for now)
• all libraries standard Python extensions depend on (like sqlite3 or
  ncurses) are statically compiled in (again, it makes PyRun Linux
  only)
• few I/O functions in CPython are patched to make most zip unsafe
  packages work out of the box (read Zip safety
  hacks section below)

Download

Exxo is self-hosting. You can download it
here.
The archive contains just one file: exxo binary you should put somewhere
in your PATH.

Quick start

Your package needs to have a working setup.py script. We'll use a
sample project from example directory in exxo git
repository. It's a simple Flask
application that prints connecting IP address. It demonstrates using a C
extension (gevent), handling data files (Flask templates and static
assets) and embedding gunicorn - all in one portable binary.

Create a new virtualenv and activate it with:

exxo venv /tmp/myenv
. /tmp/myenv/bin/activate

The default Python version is 3.5. Use exxo venv -p 2.7 for Python
2.7.

You can use the virtualenv in regular way. To build the target binary:

cd example
exxo build

You'll find the binary under dist directory. Go on and copy it to
some server and see if it works.

If you have upx installed (apt-get install upx or dnf install upx)
you can use -c flag (exxo build -c) to compress PyRun binary and
save some space.

Showcase

I plan to build few popular Python projects as a showcase of exxo
capabilities. For now there's only one.

Sentry

Link to
download

Required shared libs: apt-get install -y libpq5 libxml2 libxslt1.1

Sentry is a great error capturing and
reporting tool - a life saver, if your code lives in a highly
distributed environment. It's also a huge Django app, which makes it a
good test bed for exxo.

Differences with similar projects

There's already a significant competition for exxo, including prominent
projects like pex or
PyInstaller. Here are few things I'd
like to see exxo doing differently:

• single binary
• the binary should be almost 100% standalone (i.e. Python doesn't
  have to be preinstalled)
• good startup performance so that exxo can be used for small, short
  lived apps (this means not unpacking everything to temporary
  locations)
• user-friendliness: should stick to familiar solutions like
  virtualenv or setuptools
• should support at least most popular packages out of the box without
  manual tweaks at user side
• investment in zipapps - even if they need special attention today,
  they are the cleanest and most modern way of bundling Python apps

Caveats

Although exxo binary itself is statically linked, included C extensions
(if any) are not. All required shared libraries must be installed on the
target machine. For example, if you use lxml, you must install
libxml2. This shortcoming may be fixed in the future.

Also, exxo still links dynamically glibc for practical reasons (nsswitch
support, etc.). Although glibc uses ELF symbol versioning, you
shouldn't build your project on a machine with much newer version of
glibc than installed on destination server. Exxo release itself is built
on Ubuntu 10.04 (with openssl 1.0+) to make sure it runs on every
distro, including Centos 6.

Because your application is run as zipapp, it should be zip safe. This
applies to all dependencies too, although exxo is armed in few hacks to
make many third-party packages run out of the box (see Zip safety
hacks section below). The main violation against zip
safety is using filesystem API to read data files from inside your
package. Don't do this:

open(os.path.join(os.path.dirname(__file__), 'index.html'))

Instead use pkgutil
module and its get_data function:

pkgutil.get_data('mypackage', 'index.html')

or
pkg_resources
module from setuptools for more sophisticated API.

Note that your setup.py must have one (and exactly one)
console_scripts entry point defined for exxo build to work
correctly.

Although exxo tries hard to load everything directly from an executable,
some resources still have to be unzipped to a temporary directory due to
OS limitations. This applies mostly to bundled binaries (C extensions,
shared libraries for ctypes, ELF binaries), as it's nearly impossible
to dlopen directly from a zip. One serious limitation coming from this
behaviour is that an exxo binary won't work, if your /tmp directory
happens to be mounted with -o noexec.

Zip safety hacks

Exxo implements few patches over CPython to improve zip compatibility
out of the box.

Many popular Python packages are zip unsafe (including Django). Luckily
most of zip unsafe code follows the same pattern of loading bundled
resources mentioned in previous section:

open(os.path.join(os.path.dirname(__file__), 'templates', 'index.html'))

If loaded from an unpatched exxo binary, it will fail with an exception
like:

NotADirectoryError: [Errno 20] Not a directory: '/usr/bin/djangoapp/app/templates/index.html'

The erroneous path is clearly built from two parts: a path to exxo
binary (/usr/bin/djangoapp) and a path inside zip
(app/templates/index.html). Exxo patches several standard I/O
functions inside CPython to detect the above pattern and return an
object from zip instead of an error. This simple hack vastly improves
zip compatibility - to the point it's possible to build Django apps out
of the box.

Here's a list of functions and modules patched so far:

• open
• os.stat
• os.listdir
• ctypes (requires unpacking to temporary location)
• subprocess (requires unpacking to temporary location)

Building exxo from sources

Building was tested only on Ubuntu. Python 3.5 is also required.

Install build dependencies with:

apt-get install -y gcc make patch wget tar gzip bzip2 xz-utils blt-dev libbluetooth-dev libbz2-dev libc-dev-bin libc6-dev libdb4.8-dev libexpat1-dev libffi-dev libfontconfig1-dev libfreetype6-dev libncurses5-dev libncursesw5-dev libpthread-stubs0-dev libreadline-dev libreadline6-dev libsqlite3-dev libssl-dev libstdc++6-4.4-dev libx11-dev libxau-dev libxcb1-dev libxdmcp-dev libxext-dev libxft-dev libxrender-dev libxss-dev linux-libc-dev tcl8.5-dev tk8.5-dev x11proto-core-dev x11proto-input-dev x11proto-kb-dev x11proto-render-dev x11proto-scrnsaver-dev x11proto-xext-dev xtrans-dev zlib1g-dev liblzma-dev upx

Build PyRun binaries with:

python3 -m exxo.bootstrap all

From this point exxo is usable as python3 -m exxo.exxo. Type
make build to build exxo binary under dist directory.