Is there a way to compile a Python program to binary and use it with a Scratch Dockerfile?

Question

I've been playing around with docker images recently. I saw this docker doc on using FROM scratch . I am trying to see how far I can take this just for fun. I program in python. The doc says to compile the example C program to a binary, copy it to the container and then run it. In the container, I can not run python <program_file>. I saw this stack exchange post about compiling a python file to a binary, which meets our test use case here. It mentions using pyinstaller . So I run it on a test hello.py file which justs prints Hello with pyinstaller hello.py and I get a bunch of messages about building the projects. Okay, good. I can run the binary in my local machine by running "dist/hello" (this is the binary program mentioned by the post. So I write my Dockerfile to copy this program over and run it. My Dockerfile is

FROM scratch

ADD dist/hello /
CMD ["./hello"]

I run docker build. -t "hello:1.0" docker build. -t "hello:1.0" and then docker run hello:1.0 and.... I get an error messgage:

standard_init_linux.go:211: exec user process caused "no such file or directory"

What gives? What did I go wrong? Is it possible to get pyinstaller to compile a binary python project (multiple files, instead of just this one), then use the scratch image to run it. Are there any caveats if this is possible?

Answer 1

So the answer is to use Google's distroless image. They have an example on their github that I have slightly edited as follows.:

# Build a virtualenv using the appropriate Debian release
# * Install python3-venv for the built-in Python3 venv module (not installed by default)
# * Install gcc libpython3-dev to compile C Python modules
# * Update pip to support bdist_wheel
FROM debian:buster-slim AS build
RUN apt-get update && \
    apt-get install --no-install-suggests --no-install-recommends --yes python3-venv gcc libpython3-dev && \
    python3 -m venv /venv && \
    /venv/bin/pip install --upgrade pip

# Build the virtualenv as a separate step: Only re-execute this step when requirements.txt changes
FROM build AS build-venv
COPY requirements.txt /requirements.txt
RUN /venv/bin/pip install --disable-pip-version-check -r /requirements.txt

# Copy the virtualenv into a distroless image
FROM gcr.io/distroless/python3-debian10
COPY --from=build-venv /venv /venv
COPY . /app
WORKDIR /app
ENTRYPOINT ["/venv/bin/python3", "hello.py"]

Just posting this in case someone is wondering. Definitely a cool thing.

Link to google distroless image

The video that helped me a lot