Adapt feelpp user id to $UID given bu --user

[prudhomm]

We need to solve the userid issue on our docker images
see https://medium.com/@mccode/understanding-how-uid-and-gid-work-in-docker-containers-c37a01d01cf

[gdolle]

a7253b8 seems not to solve the problem.
It changes the uid to 9001 not the user one.
Using the option docker run -it --rm --user $UID:$GID feelpp/feelpp-toolboxes rises a priviledge error when performing useradd in the container. (atlas)

hared/:/feel feelpp/feelpp-toolboxes 
Starting with UID : 9001
useradd: Permission denied.
useradd: cannot lock /etc/passwd; try again later.
/usr/local/bin/start.sh: line 7: /etc/sudoers: Permission denied
sudo: /usr/bin/sudo must be owned by uid 0 and have the setuid bit set
sudo: /usr/bin/sudo must be owned by uid 0 and have the setuid bit set
chown: invalid user: 'user.user'

[gdolle]

It's ok. The command is the following

docker run --rm -it -h feelpp  -e LOCAL_USER_ID=`id -u $USER` -v ${HOME}/feel:/feel feelpp/feelpp-toolboxes

NB: The link to the doc also
https://denibertovic.com/posts/handling-permissions-with-docker-volumes/