Nrthugu

I have the following project structure for one of my Python project:

raspi-motion-detection

|-- project

    |-- core

        |-- motion_detector.py

    |-- conf

        |-- conf.json

I then have the following Dockerfile:

FROM     jfloff/alpine-python

RUN      mkdir -p /raspi_motion_detection/project

WORKDIR  /raspi_motion_detection/project

COPY     ./ $WORKDIR/

COPY     ./requirements.txt $WORKDIR/

ADD      . $WORKDIR

CMD      ["python", "/core/motion_detector.py --conf conf/conf.json"]

Building the image works fine, but when I tried to run it, I get the following error:

Joes-MacBook-Pro-78:project joe$ docker run joesan/dummy

python: can't open file '/raspi_motion_detection/project/core/motion_detector.py --conf /raspi_motion_detection/project/conf/conf.json': [Errno 2] No such file or directory

Joes-MacBook-Pro-78:project joe$

Any ideas as to what is happening? I did in fact ADD the WORKDIR to the Docker runtime, but still it would not find the necessary Python file.

In the last line of your Dockerfile:

CMD ["python", "/core/motion_detector.py --conf conf/conf.json"]

When the container starts up it is trying to launch python and pass it a single argument, which it interprets as the filename of a script to run. That argument, which is interpreted in its entirety as a script name, is /core/... conf/conf.json. Since you don't have a single file with that name, spaces and options and all, Python fails.

If you're using the JSON-ish syntax you need to break each separate argument into its own "word":

CMD ["python", "core/motion_detector.py", "--conf", "conf/conf.json"]

(Note that the WORKDIR directive globally changes the working directory for all subsequent commands, the default directory for COPY and ADD directives, and any ENTRYPOINT and/or CMD that eventually gets run. There's no $WORKDIR variable you can reference, and I suspect variable expansion is actually causing files end up in the container root directory when you don't expect. Try just COPY ./ ./ to add content to the image.)

Well you use fully qualified paths like they are relative.

Assuming that your Dockerfile is situated in the raspi-motion-detection folder in your project structure...

CMD      ["python", "/core/motion_detector.py", "--conf", "conf/conf.json"]

The /core... part (note I broke all the command parts into separate items) will actually point to a location relative to the root folder as it starts with a '/' and it should actially look from here:

/raspi_motion_detection/project/project/core/motion_detector.py

the same goes for the conf/conf.json that one will actually point to something relative to the WORKDIR. you might want to be more specific here too :-)

you can check your config by running something like:

docker run -it --rm your_image /bin/bash

and then look around how and what you actually added where with your build.

Your Dockerfile seems to be wrong on some points too

• You can not reference WORKDIR with $WORKDIR


• You copy a requirements.txt file but never run it so it will probably never do anything


• You see to copy the whole structure and dat will include the Dockerfile which is unnecessary

Hope it helps