Kolawole Mangabo

Optimize Docker Size Image with Python Environment.

Building Docker image with Python can be well quite heavy.

For a multistage build for example, instead of building wheels at each, you can specify a path for the python environment once it’s initialized at the first stage of the build.

ENV PATH="/opt/venv/bin:$PATH"

Make sure you have created the virtual environment tho.👀

RUN python -m venv /opt/venv
ENV PATH="/opt/venv/bin:$PATH"

Here’s an example with two steps:

# first stage
FROM python:3.10-slim as builder

WORKDIR /app

ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1

RUN pip install virtualenv

RUN virtualenv /opt/venv
ENV PATH="/opt/venv/bin:$PATH"

COPY requirements.txt .
RUN pip install -r requirements.txt

# another stage
FROM python:3.10-slim

COPY --from=builder /opt/venv /opt/venv

WORKDIR /app

ENV PATH="/opt/venv/bin:$PATH"

Summary

In conclusion, here are the steps again 🚀:

  • Create the virtual environment in the builder image
  • Copy the virtual environment to the final image