Great work on cutting down your image size with multi-stage builds already! Let's tackle that bloated site-packages directory and squeeze even more size out of your image. Here are actionable steps tailored to your setup:

1. Strip Out Unnecessary Development Dependencies #

Looking at your requirements.txt, it's packed with dev-only tools like autoflake, pytest, flake8, mypy, and coverage—these have no place in a production image. Double-check your requirements-frozen-prod.txt to ensure these are fully removed. Even a single dev dependency can add tens of MBs, so this is the lowest-hanging fruit.

2. Clean Up Python site-packages Redundancies #

Most Python packages include extra files that aren't needed in production (docs, tests, examples, .pyc files, etc.). Add a cleanup step right after installing your Python dependencies in stage2:

RUN pip install -U pip && \
    pip install --no-cache-dir --user -r requirements-frozen-prod.txt && \
    # Delete test/docs/example directories
    find /root/.local/lib/python3.8/site-packages -type d -name "tests" -o -name "test" -o -name "docs" -o -name "examples" | xargs rm -rf && \
    # Remove non-essential files (keep LICENSEs if needed)
    find /root/.local/lib/python3.8/site-packages -type f -name "*.pyc" -o -name "*.pyo" -o -name "*.md" -o -name "*.rst" ! -name "LICENSE" | xargs rm -rf && \
    # Trim dist-info files
    rm -rf /root/.local/lib/python3.8/site-packages/*.dist-info/WHEEL /root/.local/lib/python3.8/site-packages/*.dist-info/RECORD

This can easily shave 100-200MB off your site-packages directory.

3. Optimize R Package Installation #

Your R setup is also contributing to the image size. Tweak the R package install command to skip docs, demos, and unnecessary files:

RUN R -e "remotes::install_local('.', dependencies=T, Ncpus=3, INSTALL_opts=c('--no-docs', '--no-demo', '--no-help'))"

Then, clean up R's site-library in stage2 before copying to the final image:

RUN find /usr/local/lib/R/site-library -type d -name "doc" -o -name "tests" -o -name "demo" | xargs rm -rf

4. Use a More Minimal Base Image (Optional but Impactful) #

The tiangolo/uvicorn-gunicorn-fastapi image is convenient, but you could switch to a raw python:3.8-slim base and install only what you need. This avoids any hidden extras in the pre-built image. For example:

FROM python:3.8-slim As stage1
# Then manually install uvicorn/gunicorn in stage2:
RUN pip install --no-cache-dir --user uvicorn gunicorn fastapi

If you're feeling adventurous, try python:3.8-alpine—it's much smaller (~100MB vs ~200MB for slim), but note that some packages (like numpy, scipy) may require compiling from source, which adds build time and needs extra dependencies (e.g., gcc, musl-dev). You can mitigate this by using pre-built wheels for Alpine where available.

5. Trim Down System Dependencies #

In stage1, you're installing build-essential and gfortran—these are only needed for compiling R/Python packages. You can purge them after installation to save space:

RUN apt-get update && apt-get install --no-install-recommends -y ... build-essential gfortran ... && \
    # Install your packages, then purge build tools
    apt-get purge --auto-remove -y build-essential gfortran && \
    rm -rf /var/lib/apt/lists/* && \
    apt-get clean

Also, replace r-base with r-base-core if you don't need the full R suite—it's smaller and includes only essential components.

6. Optimize Multi-Stage Copy Operations #

Instead of copying entire directories like /root/.local, consider copying only the specific subdirectories you need. For example:

COPY --from=stage2 /root/.local/lib/python3.8/site-packages /root/.local/lib/python3.8/site-packages
COPY --from=stage2 /root/.local/bin /root/.local/bin

This avoids copying any accidental junk that might have ended up in /root/.local.

7. Enable Docker BuildKit #

BuildKit optimizes caching and reduces unnecessary layers. Add this line at the top of your Dockerfile to enable it:

# syntax=docker/dockerfile:1.4

Then build with DOCKER_BUILDKIT=1 docker build .—this can help reduce overall image size by more efficiently managing layers.

By combining these steps, you should be able to get your image well below 1.5GB, with a significantly smaller site-packages directory. Start with removing dev dependencies and cleaning up package files—those will give you the biggest wins with the least effort.

内容的提问来源于stack exchange，提问作者user2439278