Access denied when added entrypoint (dockerfile)

I just started learning how to create your own dockerfile and image, but I keep getting /bin/sh: 1: /app/app.sh: Permission denied when running docker run --rm 9c33 (my image id is 9c3321cd2fe82768cc953d3e082f26c5583465a864be2d47b4187148088f4e58)

My docker file contains:

FROM ubuntu
COPY . /app
RUN apt -y update && apt -y install curl
ENTRYPOINT /app/app.sh

It worked fine before adding the entrypoint

I tried using chmod +x to give me permission to that specific file, but I receive the same message of denied access
Here is an image of my folders, if it helps. I am running my commands from this location as well

When running ls -la, here is the output

drwxr-xr-x  3 skyzreal skyzreal 4096 Jun 14 10:39 .
drwxr-xr-x 24 skyzreal skyzreal 4096 Jun 14 10:40 ..
-rw-r--r--  1 skyzreal skyzreal  113 Jun 15 09:50 Dockerfile
-rw-r--r--  1 skyzreal skyzreal   89 Jun 14 10:36 Dockerfile:Zone.Identifier
-rwxr-xr-x  1 skyzreal skyzreal  876 Jun 14 10:36 app.sh
-rw-r--r--  1 skyzreal skyzreal   89 Jun 14 10:36 app.sh:Zone.Identifier
drwxr-xr-x  2 skyzreal skyzreal 4096 Jun 14 10:39 include
-rw-r--r--  1 skyzreal skyzreal  169 Jun 14 10:36 ubuntu.Dockerfile
-rw-r--r--  1 skyzreal skyzreal   89 Jun 14 10:36 ubuntu.Dockerfile:Zone.Identifier

When it comes to filesystems, there are usually permissions that one needs to set up in order to be able to read, write and/or execute a file. In most unix based systems, permissions can be changed using the chmod command.

To grant rwxr-xr-x permission (which is required if you want to run a sh file), you'd need to execute the following command:

chmod 755 /app/app.sh

In order to do this via docker, you can use the RUN command which basically takes in an array of strings and executes them as a command, adding a space in between each string:

RUN ["chmod", "755", "/app/app.sh"]

This should solve the issue.

Additionally, most unix based systems also provide a way to grand access to a specific user (as in root or in OP's case skyzreal). To change ownership of a file, you will need to use the chown command:

RUN ["chown", "your_user:your_user", "/path/to/file"]

These commands are quite simple to learn but are very important because even if you know how to use docker, if you don't know about most basic command line tools and commands, you are doomed to get stuck at some point.