Generate HAProxy PostgreSQL TCP Check

haproxy-pgsql-tcp-check

#! /bin/sh

# haproxy-pgsql-tcp-check - Generate HAProxy PostgreSQL TCP Check
# Copyright (C) 2021 Matous Jan Fialka, <https://mjf.cz/>
# Released under the terms of "The MIT License"
#
# See https://www.postgresql.org/docs/current/protocol-message-formats.html

if [ $# -lt 2 -o $# -gt 3 ]; then
	printf -- 'Usage: %s USER DATABASE ["leader"]\n' "${0##*/}" >&2
	exit 1
fi

cat <<- EOT
option tcp-check
tcp-check connect
EOT

printf -- 'tcp-check send-binary %08x00030000%s00%s00%s00%s0000\n' \
  $((0x19 + ${#1} + ${#2})) \
  $(tr -d '\n' <<< 'user' |xxd -ps) \
  $(tr -d '\n' <<< "$1" |xxd -ps) \
  $(tr -d '\n' <<< 'database' |xxd -ps) \
  $(tr -d '\n' <<< "$2" |xxd -ps)

if [ "$3" == 'leader' ]; then
	r='66'
else
	r='74'
fi

cat <<- EOT
tcp-check expect binary 520000000800000000
tcp-check send-binary 510000002073656c6563742070675f69735f696e5f7265636f7665727928293b00
tcp-check expect binary 540000002a000170675f69735f696e5f7265636f7665727900000000000000000000100001ffffffff0000440000000b000100000001$r
tcp-check send-binary 5800000004
EOT

# vi:ft=sh