docker build from inside container

Question

I'm trying to build a docker image from inside a container using the Python docker SDK. The build command

client.build(dockerfile="my.Dockerfile", path=".", tag="my-tag")

fails with

OSError: Can not read file in context: /proc/1/mem

Answer 1

The issue was that docker cannot build from the container's root directory, which was implicit due to the build context path='.' . This can easily be fixed by using a working directory in the Dockerfile of the container performing the build operation, eg

FROM python:3.9-slim
RUN apt-get update -y
WORKDIR my-workdir        <-- ADD TO FIX
COPY . .
CMD python -m my-script