#! /usr/bin/perl -w

use strict;
use Munin::Plugin;

=head1 NAME

relayd - Plugin to show statistics about relayd load balancer.

=head1 CONFIGURATION

The following environment variables are used by this plugin:

=over 4

=item logfile

The file where MailScanner logs its action (Default:
/var/log/relayd.log)

=item logtail

The location of the logtail command (Default: /usr/sbin/logtail)

=item offsetfile

The location of the offset file (Default:
/var/log/munin/plugin-state/munin-relayd.offset)

=back

=head1 USAGE

Requires the logtail command somewhere in path

=head1 TODO

Parsing relayd.conf would allow us to do the following:

 * determine the hosts in config (may be necessary!)
 * determine if the table is completely down (may be *impossible* if a partial
   downtime becomes complete between two runs)

=head1 MAGIC MARKERS

 #%# family=contrib
 #%# capabilities=

We should have "suggest" once we implement more than availability. We should
also autoconf (check if logtail and the logfile exist, basically).

See http://munin-monitoring.org/wiki/ConcisePlugins

=cut

my $logfile = '/var/log/relayd.log';
my $logtail = '/usr/sbin/logtail';
my $offsetfile = "/var/munin/plugin-state/munin-relayd.offset";
my $configfile = "/usr/local/etc/relayd.conf";

(defined($ENV{'logfile'})) and $logfile = $ENV{'logfile'};
(defined($ENV{'logtail'})) and $logtail = $ENV{'logtail'};
(defined($ENV{'offsetfile'})) and $offsetfile = $ENV{'offsetfile'};
(defined($ENV{'configfile'})) and $configfile = $ENV{'offsetfile'};

my $cmd = (defined($ARGV[0])) ? $ARGV[0] : '';

my @hosts = ();
open(my $conf, "<", $configfile) or die "can't open $configfile: $!";
my $content = join("", <$conf>);
while ( $content =~ /table\s*<([^>]*)>\s*{([^}]*)}/g) {
	my $hosts = $2;
	$hosts =~ s/#.*$//mg; # comments
	$hosts =~ s/^\s+//mg; # trim spaces before lines
	print "table $1: $hosts\n" if defined $ENV{MUNIN_DEBUG};
	push @hosts , split /\s+/, $hosts;
}

if ($cmd eq 'config') {
	print("multigraph relayd_avail\n\n");
	print("graph_title Relayd host availability\n");
	print("graph_args --lower-limit 0\n");
	print("graph_vlabel % availability\n");
	print("graph_category Load balancer\n");
	print("graph_info Ratio of time when this host was up. This is provided by relayd itself (not averaged by this plugin)\n");
	for my $host (@hosts) {
		my $clean = clean_fieldname($host);
		print("$clean.label $host\n");
	}
	print("\nmultigraph relayd_incidents\n\n");
	print("graph_title Relayd host incidents\n");
	print("graph_args --lower-limit 0\n");
	print("graph_vlabel down incidents\n");
	print("graph_category Load balancer\n");
	print("graph_info Number of times this host went down during \${graph_period}\n");
	for my $host (@hosts) {
		my $clean = clean_fieldname($host);
		print("$clean.type ABSOLUTE\n");
		print("$clean.label $host\n");
	}
	exit(0);
}

# sample lines:
# Mar  8 23:05:28 rtr0 relayd[81814]: host 209.44.112.101, check http code (2000ms), state up -> down, availability 97.83%
# Mar  8 23:05:28 rtr0 relayd[81814]: host 209.44.112.96, check http code (2001ms), state up -> down, availability 98.12%
# Mar  8 23:05:31 rtr0 relayd[81813]: table hag: 1 added, 2 deleted, 0 changed, 0 killed
# Mar  8 23:05:31 rtr0 relayd[81814]: host 209.44.112.101, check http code (3ms), state down -> up, availability 97.83%
# Mar  8 23:05:31 rtr0 relayd[81814]: host 209.44.112.96, check http code (3ms), state down -> up, availability 98.12%
# Mar  8 23:05:36 rtr0 relayd[81813]: table hag: 2 added, 1 deleted, 0 changed, 0 killed
# Mar  8 23:21:58 rtr0 relayd[81814]: host 209.44.112.96, check http code (2000ms), state up -> down, availability 98.12%
# Mar  8 23:22:01 rtr0 relayd[81813]: table hag: 0 added, 1 deleted, 0 changed, 0 killed

my (%avail, %down);

open(my $log, "$logtail -f $logfile -o $offsetfile |") or die("cannot open $logfile: $!");
#open(my $log, "tail -100 $logfile |") or die("cannot open $logfile: $!");
while (<$log>) {
	if (/host ([^,]*), check[^,]*, state [^>]* -> ([^,]*), availability ([0-9]+.[0-9]+)%/) {
		my $host = clean_fieldname($1);
		$host = clean_fieldname('host'.$1) unless ($host ne '_');

		$down{$host} = 0 unless defined $down{$host};
		$down{$host}++ if $2 eq 'down';
		# yes, we overwrite previous value and take only the recent one. be sad.
		$avail{$host} = $3;
	}
}
close($log) or warn "failed to close pipe: $!";

print "multigraph relayd_avail\n\n";
for my $host (@hosts) {
  	print "$host.value " . ($avail{$host} || 'NaN'). "\n";
}

print "\nmultigraph relayd_incidents\n\n";
for my $host (@hosts) {
	print "$host.value " . ($down{$host} || 0). "\n";
}