BusyBox `adduser` was reading config from `/etc` that unnecessarily populates the home folder with various dot files.
Alternative approach is to create the user and home folder manually. This avoids some extra files like the `-` suffixed backup copies from `adduser`.
- If local folder ownership is for example `644` it will fail to handle the `COPY` regardless (while `744` would work).
- Creating the directory with higher permissions in the container does not appear to help.
Create `testssl` user (_and group_) with no password (`-D`) and default their shell to bash (`-s`):
- A group will implicitly be created with the same value as the user. `addgroup testssl` and `-G testssl` are not needed.
- Gecos data (`-g "testssl user"`) doesn't appear relevant to the project to be required? The default gecos value (`Linux User,,,`) should be fine.
Brennan Kinney