docker run local script without host volumes

Question

The goal is to add data to my database server containers of a multi-container web app from a download using curl once the database containers are running. I can do this from docker-compose.yml or from docker run independent of the web app, as long as I use host volumes.

How do I do it without using host volumes or web app specific Dockerfiles?

Docker Compose example with host volumes:

dbinit:
build: ./webtools_config/initdb
command: bash -c "/tmp/webtools_config/dbinit.sh"
volumes:
 - ./webtools_config:/tmp/webtools_config
links:
 - db1
 - db2

Example of a docker run, that I would like to pass a script file local to the docker client such as ./dbinit.sh:

docker run -a stdin -a stdout -i -t \
--link dir_db1_1:db1 \
--link dir_db2_1:db2 \
initdb /bin/sh -c "./dbinit.sh"

Answer 1

The solutions I have found are:

docker run tomdavidson/initdb bash -c "`cat initdb.sh`"

and

Set an ENV VAR equal to your script and set up your Docker image to run the script (of course one can ADD/COPY and use host volumes but that is not this question), for example:

docker run -d -e ADD_INIT_SCRIPT="`cat custom-script.sh`" tomdavidson/debian 

tomdavidson/debian's CMD runs a script with:

if [ "${ADD_INIT_SCRIPT}" != "**None**" ]; then
  echo "Executing ADD_INIT_SCRIPT ..."
  bash -c "${ADD_INIT_SCRIPT}"
fi

https://registry.hub.docker.com/u/tomdavidson/debian/

Answer 2

If I understand you correctly you can eliminate linking host volumes by building image with this script.

Your Dockerfile:

# Dockerfile 
...
ADD your-script-on-host.sh /app/your-script-in-container.sh
RUN /app/your-script-in-container.sh
# Your CMD here

Note that way you will be able to update and run this script only while building the image.