post_install() {
  getent group umurmur > /dev/null || groupadd -r umurmur 1>/dev/null
  getent passwd umurmur > /dev/null || useradd -r -M -g umurmur -s /bin/false umurmur 1>/dev/null
}

post_upgrade() {
  post_install
}

post_remove() {
  getent passwd umurmur > /dev/null && userdel umurmur 1>/dev/null
  getent group umurmur > /dev/null && groupdel umurmur 1>/dev/null
}