fixed_coredns=$(
      printf '%s' "${original_coredns}" | sed \
        -e 's/^.*kubernetes cluster\.local/& internal/' \
        -e '/^.*upstream$/d' \
        -e '/^.*fallthrough.*$/d' \
        -e '/^.*forward . \/etc\/resolv.conf$/d' \
        -e '/^.*loop$/d' \
    )
    echo "Patched CoreDNS config:"
    echo "${fixed_coredns}"
    printf '%s' "${fixed_coredns}" | kubectl apply -f -
  fi
}