Recently, I’ve been taking some time to improve my technical skills. I started writing more tests, setting up CI/CD pipelines, and doing automated deployments. Along with the learnings are building tools that I can reuse to optimize my process. As example of it is a docker image that helps me write better code in Python.

I decided to create a simple docker image that can format my code properly and adheres to the PEP8 standard as much as possible. While I’m not a fan the character limit per line (I changed mine to 100), I’m trying to follow it to improve how I write code in Python.

To use the docker image, here’s the command:

docker pull jpbalbin/python-code-checker:0.1

The docker image contains two tools: black and pylint.

Black is so convenient to use. It basically formats your code. There is no need to think more about code formatting. Just run black and your code format is basically the same all through out. There is not much configuration can be done. The only config that I changed is the character line limit.

While black formats your code, pylint does code analysis in your code. It ensures that you follow the PEP8 standard, error detection, and provide refactoring tips. It also provides a score for your code. I always try to maintain a perfect 10/10 score in pylint.

I used these two tools with these commands:

$ docker run --rm -v $(pwd):/app jpbalbin/python-code-checker:0.1 black <.py file / folder>

reformatted fitbit_grapher.py
All done! ✨ 🍰 ✨
1 file reformatted.

$ docker run --rm -v $(pwd):/app jpbalbin/python-code-checker:0.1 pylint <.py file / folder>

************* Module fitbit_grapher
fitbit_grapher.py:1:0: C0111: Missing module docstring (missing-docstring)
fitbit_grapher.py:7:0: E0401: Unable to import 'matplotlib.pyplot' (import-error)
fitbit_grapher.py:11:0: C0411: standard import "from collections import OrderedDict" should be placed before "import arrow" (wrong-import-order)

-----------------------------------
Your code has been rated at 0.39/10

The usual process for me is that I run black first to format my code. This ensures that my code will follow PEP8 as much as possible. Afterwards, I run pylint to detect PEP8 violations and other ways to improve code.

Another thing about this docker image is that it can easily be integrated into your existing CI/CD pipeline. Black and pylint provide helpful error messages that can stop the integration/deployment. This is good to maintain the readability and code quality of the project.

For black, we can include a --check flag to determine what files need to changed without reformatting it.

$ docker run --rm -v $(pwd):/app jpbalbin/python-code-checker:0.1 black --check <.py file / folder>

Currently, I’m using this docker image for my Python projects. But this still lacks proper code testing. I’m currently reading about testing in Python and how to do it in proper way. I might improve these by adding testing and code coverage tools.