The best Docker base image for Python

Optimized size

The official Docker Python image in its slim variant—e.g. python:3.9-slim-buster—is a good base image for most use cases. it’s 41MB to download, 114MB when uncompressed to disk, it gives you the latest Python releases, it’s easy to use and it’s got all the benefits of Debian Buster.

Optimized performance

If you care about performance, you’ll want to use ubuntu:20.04. Having run some benchmarks comparing multiple Python builds, it turns out that switching to Ubuntu 20.04 can give you a 20% performance boost. As such, if Python performance matters to you, I would recommend using the ubuntu:20.04 image. It’s a bit more annoying to set up, and for some reason gets updates less often, but it will be faster.

Ref: https://pythonspeed.com/articles/base-image-python-docker-images/