create a symlink in an unprivileged container error - docker

Question

I'm running K8s deployment and trying to harden the security of one of my pod and because of that I started using the following docker image:
nginxinc/nginx-unprivileged:alpine
The problem is that I need to create a symlink and cannot get it done.
Here is the structure of my dockerfile
FROM nginxinc/nginx-unprivileged:alpine
ARG name
ARG ver
USER root
COPY ./outbox/${name}-${ver}.tgz ./
COPY ./nginx.conf /etc/nginx/nginx.conf
COPY ./mime.types /etc/nginx/mime.types
COPY ./about.md ./
RUN mv /${name}-${ver}.tgz /usr/share/nginx/html
WORKDIR /usr/share/nginx/html
RUN tar -zxf ${name}-${ver}.tgz \
&& mv ngdist/* . \
&& mv /about.md ./assets \
&& rm -fr ngdist web-ui-${ver}.tgz \
&& mkdir -p /tmp/reports
RUN chown -R 1001 /usr/share/nginx/html/
COPY ./entrypoint.sh.${name} /bin/entrypoint.sh
RUN chown 1001 /bin/entrypoint.sh
USER 1001
EXPOSE 8080
CMD [ "/bin/entrypoint.sh" ]
and here my entrypoint.sh
#!/bin/sh
ln -s /tmp/reports /usr/share/nginx/html/reports
and here is my container in the pod deployment yaml file
containers:
- name: web-ui
image: "myimage"
imagePullPolicy: Always
ports:
- containerPort: 8080
name: web-ui
volumeMounts:
- name: myvolume
mountPath: /tmp/reports
I tried to set the entrypoint under the root execution but that did not help either, the error i'm getting is this:
Error: failed to start container "web-ui": Error response from daemon:
OCI runtime create failed: container_linux.go:380: starting container
process caused: exec: "/bin/entrypoint.sh": permission denied: unknown

Answer 1

Like other Linux commands, a Docker container's main CMD can't run if the program it names isn't executable.
Most source-control systems will track whether or not a file is executable, and Docker COPY will preserve that permission bit. So the best way to address this is to make the scripts executable on the host:
chmod +x entrypoint.sh.*
git add entrypoint.sh.*
git commit -m 'make entrypoint scripts executable'
docker-compose build
docker-compose up -d
If that's not an option, you can fix this up in the Dockerfile too.
COPY ./entrypoint.sh.${name} /bin/entrypoint.sh
RUN chmod 0755 /bin/entrypoint.sh
Like other things in /bin, the script should usually be owned by root, executable by everyone, and writable only by its owner; you do not generally want the application to have the ability to overwrite its own code.