Giving execution right to entrypoint script does not working in Dockerfile - docker

Question

I have the following Dockerfile:
# pull official base image
FROM python:3.9.7-alpine
# set work directory
WORKDIR /usr/src/app
# set environment variables
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1
# install psycopg2 dependencies
RUN apk update \
&& apk add postgresql-dev gcc python3-dev musl-dev binutils \
&& apk add --no-cache proj-dev geos gdal
# install dependencies
RUN pip install --upgrade pip
COPY ./requirements.txt .
RUN pip install -r requirements.txt
# copy entrypoint.sh
COPY ./entrypoint.sh .
RUN sed -i 's/\r$//g' /usr/src/app/entrypoint.sh
RUN chmod +x /usr/src/app/entrypoint.sh
# copy project
COPY . .
# run entrypoint.sh
ENTRYPOINT ["/usr/src/app/entrypoint.sh"]
Building the image works fine, but when I try a docker run after building the image I get the following error:
docker: Error response from daemon: failed to create shim task: OCI runtime create failed: runc create failed: unable to start container process: exec: "/usr/src/app/entrypoint.sh": permission denied: unknown.
ERRO[0000] error waiting for container: context canceled
The line RUN chmod +x /usr/src/app/entrypoint.sh doesn't seem to work because when I comment the ENTRYPOINT statement, build the image then start a containerI can see that the execution right isn't added for that file.
Docker version is:
Docker version 20.10.23, build 7155243
I tried replacing the RUN chmod line with a --chmod=777 option to the COPY of the entrypoint and it didn't change anything.
Any idea why a chmod +x would fail in docker ?

Answer 1

I found a workaround by removing the chmod line and replacing the entrypoint line with the following:
ENTRYPOINT ["/bin/sh", "/usr/src/app/entrypoint.sh"]
This way there is no need for a execution right on the entrypoint script.
But I still don't know why the chmod doesn't work.