Docker: bash script works when run from terminal, but command not found error when run as entrypoint

Question

I have a Docker image that I have used and successfully run my script and commands inside the container through the terminal in interactive mode.

This is my super simple script (just to get started):

#!/bin/bash
cd /project/dir
catkin_make

I wanted to use my bash script as the entry point, so I modified my Dockerfile to include:

ENTRYPOINT ["entryscript"]
CMD ["/bin/bash"] #I've tried replacing this with just "bash"

When I run this like docker run myimg , I get catkin_make: not found . If I remove the custom entry point from the Dockerfile and run the container like docker run -it myimg , then I can run the script successfully like bash entryscript .

Why would the command not be discoverable when running the script as an entry point, but works if the identical script is run inside the container.

Answer 1

You did neither show how you created the container, nor how your host system is configured - so a bit of guessing is involved.

It seems to me that the catkin_make command is a command available to bash on the host - it may well reside on the path. You could find out by running 'which catkin_make'.

Next be aware any dockerized process just shares the kernel with the outside world. It seems a completely independent filesystem. if in there no catkin_make application exists, or it is not on the path of the containerized bash it simply cannot be invoked.

To have more output in such szenarios I usually start my scripts with

#!/bin/bash -x

to automatically run in debug mode. You can remove that when you feel comfortable about your script.