home_nodes.cgi

#!/usr/bin/perl

use strict;
use LWP::Simple;
use JSON;
use IO::Socket;
use Env qw(RABBITMQ_LOCAL RABBITMQ_OTHER RABBITMQ_USER RABBITMQ_PASS RABBITMQ_NODE_NAME);

sub print_headers {
  my $st = shift;
  print "Status: $st\n";
  print "Content-type: text/plain\n\n";
}

sub fail($) {
  my $reason = shift;
  print_headers("404 Not Found");
  print "FAIL: $reason";
  exit(0);
}

sub pass {
  print_headers("200 OK");
  print "PASS";
  exit(0);
}

sub node_up($) {
  my $host = shift;
  # connect to Rabbit server
  my $sock = new IO::Socket::INET ( PeerAddr => $host, PeerPort => '5672', Proto => 'tcp', Timeout => 1);
  return 0 unless $sock;

  # send the protocol header, await a Connection Start packet
  print $sock "AMQP\x{00}\x{00}\x{09}\x{01}";

  my $ret = $sock->recv($_, 7); # Type (C), Channel (n), Length (N)

  my $command;
  $sock->recv($command, 4); # Class (n), Method (n)
  close($sock);

  my $class_method = unpack("nn", $command);

  return ($class_method == (10,10)); # Connection = 10, Start = 10
}

sub home_node() {
  my $contents = get("http://$RABBITMQ_USER:$RABBITMQ_PASS\@$RABBITMQ_LOCAL:15672/api/queues");
  return 0 unless $contents;
  my $data = decode_json($contents);

  my ($my_queues, $total_queues);
  $my_queues = $total_queues = 0;

  for (my $i = 0; $i < @$data; $i++) {
    if ($RABBITMQ_NODE_NAME eq @{$data}[$i]->{node}) {
      $my_queues++;
    }
    $total_queues++;
  }

  my $quorum = int($total_queues / 2);

  if ($my_queues >= $quorum) {
    return 1;
  } else {
    return 0;
  }
}

if (node_up($RABBITMQ_LOCAL) != 1) {
  fail("Node down");
} elsif (home_node() == 1) {
  pass();
} elsif (node_up($RABBITMQ_OTHER) != 1) {
  pass();
} else {
  fail("Not home, other node up");
}

httpd.conf

# Configuration for the Load Balancer Checker
SetEnv RABBITMQ_USER adminuser
SetEnv RABBITMQ_PASS adminpassword
SetEnv RABBITMQ_LOCAL rabbitmq1.mydomain
SetEnv RABBITMQ_OTHER rabbitmq2.mydomain
SetEnv RABBITMQ_NODE_NAME rabbit@rabbitmq1