entrypoint

#!/bin/bash

if [ ! -f /.dockerenv ]; then
    echo '🚨  Do not run it outside a Docker container.' 1>&2
    exit 1
fi

# Create a user which has the common uid:gid with the host,
# or check if the user exists

host_uid=$(ls -n $0 | awk '{print $3}') # study who my owner is
host_gid=$(ls -n $0 | awk '{print $4}') # study what I belong to

user=$(cat /etc/passwd | grep ":x:$host_uid:" | cut -d: -f1)
group=$(cat /etc/group | grep ":x:$host_gid:" | cut -d: -f1)

if [ -z "$group" ]; then
  group=app
  echo "Creating a group..."
  groupadd --gid $host_gid $group
fi
if [ -z "$user" ]; then
  user=app
  echo "Creating an user..."
  useradd --uid $host_uid --gid $host_gid --shell /bin/bash $user

  # Add some default files to the home
  mkdir -p /home/$user
  cp -r /etc/skel/. /home/$user
  chown $user:$group /home/$user /home/$user/.bash* /home/$user/.profile
else
  echo "The user $user already exists in this container (id:$host_uid)"
fi

# Execute the command left, or enter `bash`
if [ $# -gt 0 ]; then
    exec su-exec $user $@
else
    exec su-exec $user bash
fi