August 2018 presentation introducing the Pipenv dependency management tool.

1. pipenv
The Future of Python Dependency Management

2. Rory Hart
Biarri Rail
Railroad Planning & Scheduling Software
CTO - Biarri Rail
@falican

3. Hiring
Senior Fullstack Python + Javascript

4. Acknowledgement
This talk liberally borrows from Kenneth Reitz’s PyCon talk of the same name.
Follow @kennethreitz - creator of Requests: HTTP for Humans

5. The Current State of Things

6. A lot of tooling for newbies
• pip
• requirements.txt
• requirements_dev.txt
• requirements_*.txt
• virtualenv
• + virtualenvwrapper
• pyenv
• + pyenv-virtualenv
• + a bunch more plugins …
• anaconda

7. This tooling has a missing feature
Management of “transitive dependencies”.
A B C
A C

8. Why do we need this?
$ pip install requests
Collecting requests
Collecting urllib3<1.24,>=1.21.1 (from requests)
Collecting certifi>=2017.4.17 (from requests)
Collecting idna<2.8,>=2.5 (from requests)
Collecting chardet<3.1.0,>=3.0.2 (from requests)
Installing collected packages: urllib3, certifi, idna, chardet, requests
Successfully installed certifi-2018.4.16 chardet-3.0.4 idna-2.6 requests-2.19.1 urllib3-1.23
$ pip install requests
Collecting requests
Collecting urllib3<1.24,>=1.21.1 (from requests)
Collecting certifi>=2017.4.17 (from requests)
Collecting idna<2.8,>=2.5 (from requests)
Collecting chardet<3.1.0,>=3.0.2 (from requests)
Installing collected packages: urllib3, certifi, idna, chardet, requests
Successfully installed certifi-2018.4.16 chardet-3.0.4 idna-2.7 requests-2.19.1 urllib3-1.23

9. But pip has this feature right?
Sort of . . .
$ pip freeze > requirements.txt
$ cat requirements.txt
certifi==2018.4.16
chardet==3.0.4
idna==2.7
requests==2.19.1
urllib3==1.23
But this mixes “what I want installed” with ”what I need installed”.

10. So we have two problems in Python
1. Managing application dependencies is complex for newbies.
2. Dependency management could be better.

11. A solution is at hand

12. What do other languages do?
Nodejs: yarn & npm (lockfile)
PHP: Composer (lockfile)
Rust: Cargo (lockfile)
Ruby: Bundler (lockfile)

13. $ cat Pipfile
[[source]]
url = "https://pypi.org/simple"
verify_ssl = true
name = "pypi"
[packages]
requests = "*”
[dev-packages]
[requires]
python_version = "3.6"
A new standard that will
eventually be supported by pip.
https://github.com/pypa/pipfile
Pipfile

14. Pipfile.lock

16. Already usable with pipenv
Officially recommended tool on python.org.
Automates virtualenv.
Simplifies different python versions (with pyenv).
Ensures deterministic builds!

17. Demo Time!

18. Questions?