在容器内运行Docker脚本应用程序

Question

I'm new to Docker and containers - I've got a Python 3 script that pulls data from a web site based on command line parameters and prints the results. It uses Redis for caching data if there's no network connection available. The Dockerfile I have looks like this

FROM ubuntu:latest
RUN apt-get update -y && apt-get -y install redis-server && apt-get install -y python3-pip python3.5-dev build-essential
COPY . /app
WORKDIR /app
RUN pip3 install -r requirements.txt
ENTRYPOINT ["python3"]
CMD ["pn.py"]

I'm able to build the image, but when I start the container it presumably runs the Python command to run the script inside the container and exits, and as a consquence I cannot see the results from the host.

The script requires command line inputs, otherwise it will fail. How can these be specified as part of a single Docker run command I can use to run the script from the host?

Alternatively how can I start the container without calling the script, and instead run the script manually inside the running container?

Answer 1

It depends on what you want to do with the results.

Assume the following:

• the ENTRYPOINT line tells the image what should be executed when you start the container. That will be PID 1 .
• when that line exists, the CMD content is used as argument(s) to the ENTRYPOINT .
• docker containers always exit when their main task (PID 1) exits.

Basically your docker is doing what it is told to do. If you want it to keep running, you should give a task that won't exit as ENTRYPOINT or CMD (if ENTRYPOINT was not present).

For manually start the container on a shell mode and see what happens, you can run it as:

docker run -ti [OPTIONS] [CONTAINER_NAME] bash

and then you'll be in a shell "into" the container, so you can run the script manually:

#~ python3 pn.py