No file found when using ENTRYPOINT

Question

I am trying to use ENTRYPOINT and whenever I do that I am getting an error as no such file or directory

Dockerfile:

FROM ubuntu:18.04

COPY . /home

COPY docker-entrypoint.sh /usr/local/bin/

RUN ln -s /usr/local/bin/docker-entrypoint.sh

WORKDIR /home
RUN chmod 777 /usr/local/bin/docker-entrypoint.sh

ENTRYPOINT ["docker-entrypoint.sh"]

CMD ["/bin/bash"]

I have tried giving it permission, tried running it with absolute path also tried this, tried it with #!/bin/bash & #!/bin/sh and in the end, I still get the file not found error.

I am not sure what the problem is.

Answer 1

The question you asked: I don't remember exactly why, but the file isn't being found because you're calling it docker-entrypoint.sh rather than ./docker-entrypoint.sh.

The question you'll ask soon: That doesn't entirely fix your problem. You've added execute privileges to the copy of docker-entrypoint.sh in /usr/local/bin, but there's another copy of the file in /home that gets found first and doesn't have execute privileges. You'll get a permissions error when you try to use it. An easy workaround (depending on what you want to do) consists of a modified entrypoint:

ENTRYPOINT ["/bin/bash", "docker-entrypoint.sh"]

Extra details if you'll be using Docker a lot: Being able to enter a container or image to examine its contents is invaluable. For ubuntu-based images, write down the following line somewhere (replace bash with sh for basically every other linux OS):

docker run -it --rm --entrypoint=bash my_image_name

This will open up a shell in that image and let you play around in the same environment the Dockerfile is running in and debug whatever is causing you problems.