Run bash command before running container

Question

I want to run a pre-existing Docker image like so:

docker run -d --name cdt-selenium selenium/standalone-firefox:3.4.0-chromium

So there is no Dockerfile that I control for this image. However, I would like to copy some files into this container.

If I did control the Dockerfile, I would like to run these commands:

RUN mkdir -p /root/cdt-tests/csv-data
COPY ./csv-data/* /root/cdt-tests/csv-data

Is there a way to run those commands in the same line as the Docker run command above?

I tried this:

docker run -d --name cdt-selenium selenium/standalone-firefox:3.4.0-chromium
docker exec cdt-selenium mkdir -p /root/cdt-tests/csv-data
docker cp cdt-selenium:/root/cdt-tests/csv-data ./csv-data

but I get a permissions error on the docker exec line

@BMitch yes, I agree, that was my other question - stackoverflow.com/questions/44146561/… current question here is a workaround, because I could not figure out how to get volumes to work... — Alexander Mills
– Alexander Mills, Commented May 24, 2017 at 20:54

BMitch · Accepted Answer · 2017-05-24 18:50:15Z

3

All images have a FROM line, and that can be any other image. So you can make a Dockerfile with:

FROM selenium/standalone-firefox:3.4.0-chromium
USER root
RUN mkdir -p /root/cdt-tests/csv-data
COPY ./csv-data/* /root/cdt-tests/csv-data
USER seluser

that will build your own image with your commands run.

You'd build it and create your own tag:

docker build -t alexander/selenium:3.4.0-chromium .

And then run it:

docker run -d --name cdt-selenium alexander/selenium:3.4.0-chromium

Edit: the exec command you ran failed because docker runs this container as a different user. You can see that in their Dockerfile. To solve that, run the exec with the root user option (-u root):

docker exec -u root cdt-selenium mkdir -p /root/cdt-tests/csv-data

edited May 24, 2017 at 18:50

answered May 24, 2017 at 18:37

BMitch

271k51 gold badges555 silver badges511 bronze badges

Sign up to request clarification or add additional context in comments.

11 Comments

Alexander Mills Over a year ago

thanks, I will try this - first though I'd like to try the docker exec/docker cp method - I updated the question - any idea how to get around that permissions problem I mention?

BMitch Over a year ago

I've updated the answer to cover the seluser that Selenium uses inside their container.

Alexander Mills Over a year ago

thanks, also using sudo seemed to work (which is surprising) => docker exec cdt-selenium sudo mkdir -p /root/cdt-tests/csv-data

Alexander Mills Over a year ago

is selenium server really ok with absolute paths to files on the fs?

Alexander Mills Over a year ago

yeah both these techniques seem to work without errors, but selenium still cannot find the files at /root/cdt-tests/csv-data/X...not really sure what's happening, any ideas?

|

Collectives™ on Stack Overflow

Run bash command before running container

1 Answer 1

11 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

11 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related