Open permissions of files in the docker container.

Please check the permissions of the files in the docker container.

This ...

root@5eccca674dd0:/# ls -al /signing-key.asc 
-rw-rw-rw-. 1 root root 15554 Sep 11  2020 /signing-key.asc

... is not looking good to me, as it is writeable for anybody.