The Packaging Gradient

There are many options to package software, particularly Python software. How do all these options fit together, and how does one decide which option is right for them? This guide takes a holistic approach, as presented at PyBay 2017.

Transcript

1. The Packaging Gradient Mahmoud Hashemi August, 2017 A Holistic Guide to Software Distribution
2. Packaging ⊡ Turning your code into a self-contained artifact (file) ⊡ For reliable transfer to and use in production environments a. Data centers b. Laptops / Phones But how? The fine art of:
3. “” “TBD” — IRL packaging instructions
4. Packaging reality ⊡ Developers leave packaging until the end ⊡ They discover what feels like a thousand options ⊡ They invent one more. a. Docs TBD
5. “” “The first 90% of the code accounts for the first 90% of development time. The last 10% of the code accounts for the other 90% of development time.” — Tom Cargill, Bell Labs The Rule
6. Packaging is not the last step. Production environment is everything.
7. LIVE CODING DEMO
8. Deploying the “script” home:~$ scp useful.py dest: --- dest:~$ python useful.py
9. python: command not found Oh, sorry, this bashrc is weird. Just a second... 1 ❌
10. ImportError: No module named requests This was working on my machine a second ago... 1 ❌❌
11. SSL certificate error: [Errno 1] _ssl.c:504: error:0D0890A1:asn1 encoding routines:ASN1_verify: unknown message digest algorithm I thought we were friends. ❌❌❌
12. The “script” import requests resp = requests.get('https://github.com/mahmoud') print(resp.status) # (that’s it)
13. Mahmoud Hashemi August, 2017 A Convenient Analogy to Software Packaging The Packing Gradient
14. ? How far are you traveling? (approximately)
15. A few blocks? A wallet or purse. A few miles? A backpack at least California? A carry-on bag The USA? A suitcase, or maybe an RV Otherwise? Any of the above — and a passport The Packing Gradient How far you travel influences what you pack low size high portability
16. The Packing Gradient Distance and accommodations determine what you pack. (hotel) (no hotel)
17. What does this look like for software? Back to our regularly scheduled program. ?
18. The standalone Python module ⊡ A .py file is a module ⊡ Standalone: only imports from the standard library ⊡ schema, ashes, boltons, bottle.py ⊡ Easy to distribute and integrate
19. The pure-Python package ⊡ A directory with a __init__.py in it is a package ⊡ Django, requests, hyperlink ⊡ Easy to install with pip • pip installs packages, after all, right?
20. Pardon my dist ⊡ A distribution is an archive of zero or more packages ⊡ Built by setuptools through setup.py ⊡ Example: sdist • Simple, source-only .tar.gz • Great for pure-Python modules and packages ⊡ Motivational case study: PIL & Pillow
21. The full Python package ⊡ Python s interoperability & performance ⊡ Pillow, numpy, SciPy, gevent ⊡ wheel • The shiny new binary distribution, or bdist • Supports most Windows, Mac, & Linux (We don’t talk about .eggs anymore.)
22. Linkin’ Libs ⊡ Static linking vs dynamic linking ⊡ Some wheels are bigger than others ⊡ System libraries • .dll & .so • libcrypto (OpenSSL) • libxml2 / libpng / libpython
23. In summary python setup.py sdist bdist_wheel upload The modern way to build and upload a Python package
24. FIN Thanks for coming! github.com/mahmoud
25. Questions? ⊡ I sure hope so! ⊡ Even wheel won’t let you install most types of software ⊡ Python’s native package management will get you: • Libraries • Basic dev tools • (that’s it)
26. PyPI is not an app store Python is general-purpose, but pip and PyPI are not
27. pip requirements ⊡ A working Python with pip installed ⊡ A network connection, probably to the Internet ⊡ Preinstalled system libraries ⊡ Build tools for target packages (gcc/clang) • For when wheels aren’t available for your platform Standard pip installation requires:
28. pip requirements You. A developer willing to sit and watch dependencies download, and debug any version conflicts, build errors, etc. But pip’s most important dependency:
29. Packaging Python ⊡ Sublime Text ⊡ EVE Online ⊡ Reddit “Python Packaging” vs “Packaging Python” How do we ship applications?
30. ⊡ Python EXecutable ⊡ Single, runnable file ⊡ No setup or install ⊡ Builds on Python’s zipimport □ superzippy □ zipapp ⊡ Same constraints as wheel Packaging Python Applications PEX PEX’s internal structure: hashbang python + zip
31. Our app on PEX <3 MB OS-specific Similar to wheels System Python Linux / Mac No setup step Web download Wiki attachment Slack/Hipchat PEX is probably The Right Way™ to distribute useful.py. Installation requires Artifact details Distribution options
32. Packaging Python Applications Anaconda’s internal layout (lib, include, bin, etc) ⊡ A whole new ecosystem ⊡ conda install applications □ postgres □ nginx □ python, itself ⊡ Built on OS and Python features □ Filesystem layout □ Python landmarking □ PatchELF Anaconda
33. Anaconda. Is. Awesome. Cross-platform, Python-first package management and social app store.
34. Our app on conda Artifact details <1 MB OS-specific .tar.bz2 Installation requires Anaconda Linux / Mac / Windows conda install step Distribution options anaconda.org conda is a good channel for distributing our tool to devs and data people
35. A bundle of py. ⊡ Bring your own Python! ⊡ Generally entails an installer. □ Dropbox □ EVE Online □ Civilization IV □ All Kivy apps ⊡ Lots of options: □ cx_Freeze, PyInstaller, osnap, bbFreeze, py2exe, py2app, pynsist, nuitka, ... Freezers Packaging Python Applications
36. Our app, frozen Artifact details <30MB OS-specific .exe / .app / etc. Installation requires Linux / Mac / Windows Executable or double-click install System libraries Distribution options Direct download App stores Freezers represent the best option for consumer software.
37. So many wheels going round. ⊡ Servers need extra attention ⊡ Chef Omnibus ⊡ Higher-level self-containment ⊡ Copies of all dependent services ⊡ Case Study: GitLab □ https://about.gitlab.com/installation/ □ https://gitlab.com/gitlab-org/omnibus-gitlab Freezers (EE) Packaging Python Applications
38. Our app on Omnibus Artifact details <100MB .rpm / .deb Installation requires Debian-/RedHat-based Linux yum or apt Minimal system libraries Distribution options Direct download PPA / package repo Omnibus could probably ship a script, but works best for applications with multiple components (services, queues, batches)
39. Intermission: bits and pieces ⊡ virtualenv ⊡ RPM, DEB, etc. On their own, not so great for users ⊡ Example: dh-virtualenv □ Analogous to PEX: includes libraries, but not Python □ Artifacts managed by your Debian package manager Many technologies, many more part than whole.
40. Like selfies, but twice as trendy. ⊡ Bring your own userspace! ⊡ Anaconda meets old autostart CDs ⊡ Example: AppImage ⊡ Case study: kdenlive Userspace Images Packaging Python Applications
41. Our app in an image Artifact details <100MB ISO 9660 Installation requires Linux chmod +x Distribution options Direct download Shared folder For Linux, an image is even better than a PEX, if a bit conservative.
42. Basically disposable, but they never seem to seal as well as they promise. ⊡ Userspace images □ + sandboxing □ + distribution ⊡ Flatpak / Snappy □ .deb vs .rpm round 2 ⊡ Docker (Moby?) “Containers” Packaging Python Applications
43. Our app, containerized Artifact details 100MB-2GB Often hidden Installation requires Linux (or equiv. virtualization) Container runtime “Pull” step Distribution options Linux app store Docker Hub/Registry Containers might be overkill for our script, but it wouldn’t top the charts for the most ridiculous image to date.
44. ⊡ Bring the whole dang kernel ⊡ Production-grade emulation ⊡ Key to the cloud Virtual Machines Screenshot of OpenStack deployment in progress. Packaging Python Applications
45. Our app, virtualized Artifact details 100MB-8GB Many formats Installation requires Any OS Hypervisor Distribution options Direct download AWS OpenStack Glance While too unwieldy for our script, VMs are only getting more powerful.
46. ⊡ Just ship the box. ⊡ Appliances! Hardware High-latency delivery, but comes fully loaded. Packaging Python Applications
47. Our app on hardware Artifact details 4" x 3" x 1" $50 Ships in 1-3 business weeks Installation requires Electricity Distribution options USPS DHL A good toss Coming soon to a Kickstarter near you.
48. Wrapping up We learned: ⊡ Packaging is the fine art of creating a distributable software artifact ⊡ A packaging design is not the last phase in a project ⊡ Python is general purpose, PyPI and pip are not ⊡ Because libraries are different than applications
49. Wrapping up 1 2 3 Packaging for Python libraries 1. .py - standalone modules 2. sdist - Pure-Python packages 3. wheel - Python packages (With room to spare for static vs. dynamic linking)
50. Wrapping up 1 1. PEX - libraries included 2. anaconda - Python ecosystem 3. freezers - Python included 4. images - system libraries included 5. containers - sandboxed images 6. virtual machines - kernel included 7. hardware - plug and play 2 3 4 5 6 7 Packaging for Python applications
51. THANKS! Questions? bit.ly/pkgrad @mhashemi