Deploying your software can become a tricky task, regardless of the language. In the spirit of the Python conferences, every conference needs at least one packaging talk. This talk is about dh-virtualenv. It's a Python packaging tool aimed for Debian-based systems and for deployment flows that already take advantage of Debian packaging with Python virtualenvs

1. dh-virtualenv
Packaging in packaging

2. @nailor
Jyrki Pulliainen
jyrki@spotify.com
Photo credit: Pontus Persson

3. What’s in this talk?
• Look at different, existing deployment strategies
• What is dh-virtualenv?
• Packaging sentry with dh-virtualenv

4. virtualenv

5. + Stable
+ Non-Python Dependencies
+ Existing infrastructure
+ Scripting

7. - Out of date
- Complex
- Global state

8. + Has the new stuff
+ De facto
+ Battle tested
+ Contained
virtualenv

10. - Native dependency
handling
- Source installs
- Random scripts
sh: mysql_config: command not found

11. What is dh-virtualenv?

12. Virtualenv inside a Debian package

13. It’s Open Source!
• GPL’d
• Documented
• Comes with a simple tutorial!

14. It’s a DebHelper Extension
• Idea stolen adapted from @hynek
* https://hynek.me/articles/python-app-deployment-with-native-packages/

15. In practice?

16. Package builder that…
1. Creates a virtualenv
2. Installs requirements.txt into that virtualenv
3. Installs your project
4. Fixes the virtualenv to match production

17. Packaging with dh-virtualenv
Case in point: sentry

18. 1. Install dh-virtualenv
apt-get install dh-virtualenv
2. Create ‘debian’ directory
3. Insert the minimal boilerplate files in there

19. debian/control:
Source: sentry
Section: python
Priority: extra
Maintainer: Jyrki Pulliainen <jyrki@spotify.com>
Build-Depends: debhelper (>= 9), python, dh-virtualenv,
python-dev
Standards-Version: 3.9.5
Package: sentry
Architecture: any
Depends: ${python:Depends}, ${misc:Depends}
Description: dh-virtualenv-packaged sentry
Amazing tool, now packaged with dh-virtualenv!

20. debian/changelog:
sentry (6.4.4-1) unstable; urgency=low
* Initial packaging with dh-virtualenv
-- Jyrki Pulliainen <jyrki@spotify.com> Wed, 23 Jul 2014 12:02:20 +0200

21. echo 9 > debian/compat

22. debian/rules:
#!/usr/bin/make -f
%:
dh $@ --with python-virtualenv

23. 5. Build your package!
dpkg-buildpackage

24. dpkg-buildpackage: source package dh-virtualenv
dpkg-buildpackage: source version 0.7-2
dpkg-buildpackage: source distribution unstable
dpkg-buildpackage: source changed by Jyrki Pulliainen <jyrki@spotify.com>
dpkg-buildpackage: host architecture i386
dpkg-source --before-build dh-virtualenv
fakeroot debian/rules clean
dh clean --with python2 --with sphinxdoc
dh_testdir
debian/rules override_dh_auto_clean
make[1]: Entering directory `/vagrant_src/dh-virtualenv'
rm -rf doc/_build
rm -f doc/dh_virtualenv.1
rm -rf dh_virtualenv.egg-info
dh_auto_clean
running clean
'build/lib.linux-i686-2.7' does not exist -- can't clean it
'build/bdist.linux-i686' does not exist -- can't clean it
removing 'build/scripts-2.7' (and everything under it)
make[1]: Leaving directory `/vagrant_src/dh-virtualenv'
dh_clean
dpkg-source -b dh-virtualenv
dpkg-source: error: can't build with source format '3.0 (quilt)': no upstream tarball found at ../
dh-virtualenv_0.7.orig.tar.{bz2,gz,lzma,xz}

25. dh_virtualenv
Running virtualenv with interpreter /usr/bin/python2
New python executable in debian/sentry/usr/share/python/sentry/bin/python2
Also creating executable in debian/sentry/usr/share/python/sentry/bin/python
Installing setuptools, pip...done.
Unpacking /vagrant_src/sentry-with-dh-virtualenv
Running setup.py (path:/tmp/pip-ttX1Ip-build/setup.py) egg_info for package from file:///
vagrant_src/sentry-with-dh-virtualenv
warning: no previously-included files matching '*~' found anywhere in distribution
Downloading/unpacking BeautifulSoup>=3.2.1,<3.3.0 (from sentry==6.4.4)
Downloading BeautifulSoup-3.2.1.tar.gz
Running setup.py (path:/vagrant_src/sentry-with-dh-virtualenv/debian/sentry/usr/share/python/
sentry/build/BeautifulSoup/setup.py) egg_info for package BeautifulSoup
Downloading/unpacking celery>=3.0.15,<3.1.0 (from sentry==6.4.4)
Downloading celery-3.0.25.tar.gz (1.1MB): 1.1MB downloaded
Running setup.py (path:/vagrant_src/sentry-with-dh-virtualenv/debian/sentry/usr/share/python/
sentry/build/celery/setup.py) egg_info for package celery
Upgrade: no old version found.
no previously-included directories found matching '*.pyc'
no previously-included directories found matching '*.sw*’

26. 5. Install the shiny Debian package in production!

28. + Non-Python dependencies
+ Existing Infrastructure
+ The new hotness
+ Contained
dh-virtualenv

29. - Can be slow to build
- Requires still digging for requirements
- Build system needs to have the exactly
same Python
dh-virtualenv

30. Thanks!
github.com/spotify/dh-virtualenv
dh-virtualenv.readthedocs.org
labs.spotify.com/2013/10/10/packaging-in-your-
packaging-dh-virtualenv/