Question 85443 in Docker Question posted in
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Python script cannot find installed libraries inside container? – Docker

I use the following Dockerfile, which builds fine into an image:

FROM python:3.8-slim-buster
ENV PYTHONDONTWRITEBYTECODE=1
ENV PYTHONPATH="$PYTHONPATH:/app"
WORKDIR /app
COPY ./app .
RUN apt-get update
RUN apt-get install -y python3-pymssql python3-requests
CMD ["python3", "main.py"]

main.py:

from pymssql import connect, InterfaceError, OperationalError

try:
    conn = connect(host, username, password, database)
except (InterfaceError, OperationalError) as e:
    raise
conn.close()

For some reason, the python3-pymssql installed libraries are not present even if I see them getting installed during the docker build process, when I do a docker run I get the following error:

Traceback (most recent call last):

  File "main.py", line 1, in <module>

    from pymssql import connect, InterfaceError, OperationalError

ModuleNotFoundError: No module named 'pymssql'

I presume I could use a pip3 install but I prefer to take advantage of pre-build apt packages. Can you please let me know what am I missing?

Thank you for your help.

Tags:

2

Answers


  1. 0

    You can install pymssql with pip only. The following Dockerfile builds and runs fine:

    FROM python:3.8-slim-buster
ENV PYTHONDONTWRITEBYTECODE 1
RUN pip install pymssql

WORKDIR /app
COPY ./app .
CMD ["python3", "main.py"]
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  2. 0

    You have two copies of Python installed, 3.8 and 3.7:

    root@367f37546ae7:/# python3 --version
Python 3.8.12
root@367f37546ae7:/# python3.7 --version
Python 3.7.3

    The image you’re basing this on, python:3.8-slim-buster, is based on Debian Buster, which uses Python 3.7 in its packages. So if you install an apt package, that’s going to install Python 3.7 and install the package for Python 3.7. Then, you launch Python 3.8, which lacks the pymssql dependency.

    You can:

    1. Use a non-Python image, and install Python using apt. This way, you’re guaranteed that the version of Python installed will be compatible with the Python dependencies from apt. For example, you could base your image on FROM debian:buster.
    2. Use a Python image, and install your dependencies with pip.
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