How do you add a path to PYTHONPATH in a Dockerfile

Question

How do you add a path to PYTHONPATH in a Dockerfile? So that when the container is run it has the correct PYTHONPATH? I'm completely new to Docker.

I've added ENV PYTHONPATH "${PYTHONPATH}:/control" to the Dockerfile as I want to add the directory /control to PYTHONPATH.

When I access the container's bash with docker exec -it trusting_spence bash and open python and run the commands below the directory control is not on the list.

import sys print(sys.path)

FROM python:2 RUN pip install requests pymongo  RUN mkdir control  COPY control_file/ /control  ENV PYTHONPATH "${PYTHONPATH}:/control"  CMD ["python","control/control_file/job.py"]  

Answer 1

Just add an ENV entry in your Dockerfile:

ENV PYTHONPATH "${PYTHONPATH}:/your/custom/path" 

Or set PYTHONPATH in your startup script.