Docker python output csv file

Question

I have a script python which should output a file csv. I'm trying to have this file in the current working directory but without success.

This is my Dockerfile

FROM python:3.6.4

RUN apt-get update && apt-get install -y libaio1 wget unzip

WORKDIR /opt/oracle 
RUN wget https://download.oracle.com/otn_software/linux/instantclient/instantclient- 
basiclite-linuxx64.zip && \ unzip instantclient-basiclite-linuxx64.zip && rm 
-f instantclient-basiclite-linuxx64.zip && \ cd /opt/oracle/instantclient* 
&& rm -f jdbc occi mysql *README jar uidrvci genezi adrci && \ echo 
/opt/oracle/instantclient > /etc/ld.so.conf.d/oracle-instantclient.conf && 
ldconfig 
RUN pip install --upgrade pip

COPY . /app 
WORKDIR /app

RUN pip install --upgrade pip 
RUN pip install pystan 
RUN apt-get -y update && python3 -m pip install cx_Oracle --upgrade 
RUN pip install -r requirements.txt

CMD [ "python", "Main.py" ]

And run the container with the following command

docker container run -v $pwd:/home/learn/rstudio_script/output image

Answer 1

Your script Main.py is probably not trying to write to /home/learn/rstudio_script/output . The working directory in the container is /app because of the last WORKDIR directive in the Dockerfile. You can override that at runtime with --workdir but then the CMD would have to be changed as well.

One solution is to have your script write files to /output/ and then run it like this:

docker container run -v $PWD:/output/ image

Answer 2

This is bad practice to bind a volume just to have 1 file on your container be saved onto your host.

Instead, what you should leverage is the copy command:

docker cp <containerId>:/file/path/within/container /host/path/target

You can set this command to auto execute with bash, after your docker run.

So something like:

#!/bin/bash

# this stores the container id
CONTAINER_ID=$(docker run -dit img)

docker cp $CONTAINER_ID:/some_path host_path

If you are adamant on using a bind volume, then as the others have pointed out, the issue is most likely your python script isn't outputting the csv to the correct path.