docker-entrypoint.sh

#!/usr/bin/env sh

MYUSER="ghost"
MYGID="10010"
MYUID="10010"
OS=""
MYUPGRADE="1"

DectectOS(){
  if [ -e /etc/alpine-release ]; then
    OS="alpine"
  elif [ -e /etc/os-release ]; then
    if grep -q "NAME=\"Ubuntu\"" /etc/os-release ; then
      OS="ubuntu"
    fi
    if grep -q "NAME=\"CentOS Linux\"" /etc/os-release ; then
      OS="centos"
    fi
  fi
}

AutoUpgrade(){
  if [ -n "${DOCKUPGRADE}" ]; then
    MYUPGRADE="${DOCKUPGRADE}"
  fi
  if [ "${MYUPGRADE}"]; then
    if [ "${OS}" == "alpine" ]; then
      apk --no-cache upgrade
      rm -rf /var/cache/apk/*
    elif [ "${OS}" == "ubuntu" ]; then
      export DEBIAN_FRONTEND=noninteractive
      apt-get update
      apt-get -y --no-install-recommends dist-upgrade
      apt-get -y autoclean
      apt-get -y clean
      apt-get -y autoremove
      rm -rf /var/lib/apt/lists/*
    elif [ "${OS}" == "centos" ]; then
      yum upgrade -y
      yum clean all
      rm -rf /var/cache/yum/*
    fi
  fi
}

ConfigureUser () {
  # Managing user
  if [ -n "${DOCKUID}" ]; then
    MYUID="${DOCKUID}"
  fi
  # Managing group
  if [ -n "${DOCKGID}" ]; then
    MYGID="${DOCKGID}"
  fi
  local OLDHOME
  local OLDGID
  local OLDUID
  if grep -q "${MYUSER}" /etc/passwd; then
    OLDUID=$(id -u "${MYUSER}")
    if [ "${DOCKUID}" != "${OLDUID}" ]; then
      OLDHOME=$(grep "$MYUSER" /etc/passwd | awk -F: '{print $6}')
      if [ "${OS}" == "alpine" ]; then
        deluser "${MYUSER}"
      else
        userdel "${MYUSER}"
      fi
      logger "Deleted user ${MYUSER}"
    fi
    if grep -q "${MYUSER}" /etc/group; then    
      OLDGID=$(id -g "${MYUSER}")
      if [ "${DOCKGID}" != "${OLDGID}" ]; then
        if [ "${OS}" == "alpine" ]; then
          delgroup "${MYUSER}"
        else
          groupdel "${MYUSER}"
        fi
        logger "Deleted group ${MYUSER}"
      fi
    fi
  fi
  if ! grep -q "${MYUSER}" /etc/group; then
    if [ "${OS}" == "alpine" ]; then
      addgroup -S -g "${MYGID}" "${MYUSER}"
    else
      groupadd -r -g "${MYGID}" "${MYUSER}"
    fi
    logger "Created group ${MYUSER}"
  fi
  if ! grep -q "${MYUSER}" /etc/passwd; then
    if [ -z "${OLDHOME}" ]; then
      OLDHOME="/home/${MYUSER}"
    fi
    if [ "${OS}" == "alpine" ]; then
      adduser -S -D -H -s /sbin/nologin -G "${MYUSER}" -h "${OLDHOME}" -u "${MYUID}" "${MYUSER}"
    else
      useradd --system --shell /sbin/nologin --gid "${MYGID}" --home "${OLDHOME}" --uid "${MYUID}" "${MYUSER}"
    fi
    logger "Created user ${MYUSER}"
    
  fi
  if [ -n "${OLDUID}" ] && [ "${DOCKUID}" != "${OLDUID}" ]; then
    logger "Fixing permissions for group ${MYUSER}"
    find / -user "${OLDUID}" -exec chown ${MYUSER} {} \;
    logger "... done!"
  fi
  if [ -n "${OLDGID}" ] && [ "${DOCKGID}" != "${OLDGID}" ]; then
    logger "Fixing permissions for group ${MYUSER}"
    find / -group "${OLDGID}" -exec chgrp ${MYUSER} {} \;
    logger "... done!"
  fi
}

DectectOS
AutoUpgrade
ConfigureUser

if [ "$1" == 'ghost' ]; then
    if [ ! -d /ghost ]; then
      mkdir /ghost
    fi
    if [ -d /ghost ]; then
      chown -R "${MYUSER}":"${MYUSER}" /ghost
      chmod -R 0750 /ghost
    fi
    cd /ghost
    exec /sbin/su-exec "${MYUSER}" npm start --production
fi

exec "$@"