pgping

function pgping() {
  help_flags=(help -h --help)
  if [[ ${help_flags[*]} =~ "$1" ]] || ([ -z "$1" ] || [ -z "$2" ]); then
    echo "usage:"
    echo
    echo "pgping <server> <port> [<username>]"
    return 0
  fi

  PROTOCOL_VERSION="\x00\x03\x00\x00"
  COMMAND="user"

  NC_TIMEOUT=3

  POSTGRES_SERVER=$1
  POSTGRES_PORT=$2
  if [ ! -z "$3" ]; then
    USERNAME=$3
  else
    USERNAME="username"
  fi

  PACKET_SIZE="\x00\x00\x00\x$(printf '%02x' $((
    4 +
    ${#PROTOCOL_VERSION} / 4 +
    ${#COMMAND} +
    1 +
    ${#USERNAME} +
    2
  )))"

  test "$(
    echo -ne "${PACKET_SIZE}${PROTOCOL_VERSION}${COMMAND}\x00${USERNAME}\x00\x00" |
    nc -w $NC_TIMEOUT $POSTGRES_SERVER $POSTGRES_PORT 2>/dev/null | head -c1
  )" == "R"

  if [ $? -eq 0 ]; then
    echo "health check passed"
    return 0
  else
    echo "health check failed"
    return 1
  fi
}

pgping "$@"