create new user for docker with SSH access only

new-ssh-user.sh

#! /bin/bash

set -ve
read -p "username: " USERNAME
read -p "public key: " PUBLIC_KEY

# https://askubuntu.com/a/94067/712137
adduser --disabled-password --gecos "" $USERNAME
usermod -aG docker $USERNAME

HOME_DIR=$( getent passwd "$USERNAME" | cut -d: -f6 )
mkdir -p $HOME_DIR/.ssh
echo ${PUBLIC_KEY} > $HOME_DIR/.ssh/authorized_keys
chown -R $USERNAME:$USERNAME $HOME_DIR
chmod 700 $HOME_DIR/.ssh
chmod 644 $HOME_DIR/.ssh/authorized_keys