Roholt

docker containers often run as the root user (uid = 0, guid = 0). Files that the users generates are therefore also owned by the root user.

By creating an extra user on the docker system, and giving that user the same uid and guid as the user on you host system you will be able to modify your files without the need to be root on you host machine.

The following assumes you created an additional user in your docker container, and that it got 1000 for uid and guid.

#!/bin/bash

# Mr. R
# 06-2020

args=$@
cmd="builder.sh ${args}"

# current working directory is a volume mount to something on the host system.
# Therefore stat -c will provide the uid and gid of the host user.
# setting this uid and gid for the container user results in files written to the
# volume as host user.
usr=`id -nu 1000`
grp=`id -ng 1000`
groupmod -g $(stat -c "%g" .) $grp
usermod -u $(stat -c "%u" .) -g $(stat -c "%g" .) $usr

# Force all volume mounts to be of the appuser!
chown -R ${usr}:${grp} ${WORKDIR}

# If nothing given, start a shell, else run the builder script with arguments.
if [ "x${args}x" == "xx" ]; then
  cmd="/bin/bash"
fi

su -m -c "PATH=${PATH}; ${cmd}" ${usr}