#!/usr/bin/perl
# vim: set filetype=perl sw=4 tabstop=4 expandtab smartindent: #

=head1 NAME

  du - Plugin to monitor multiple directories size

=head1 AUTHOR AND COPYRIGHT

  Copyright 2011-2012 Luc Didry <luc AT didry.org>

=head1 HOWTO CONFIGURE AND USE :

=over

=item - /etc/munin/plugin-conf.d/du_

     [du]
     user root
     env.interval 20 # INTERVAL OF DU POLLING IN MINUTES
     env.dirs /home/foo /home/bar # DIRECTORIES TO POLL
     env.suppr /home/ # PLEASE USE \# INSTEAD OF #
     timeout 900 # 15 MINUTES IN SECONDS

=item - /etc/munin/plugins-enabled

     ln -svf ../plugins-available/site/du


=item - restart Munin node

     sudo killall -TERM munin-node

=back

=head1 CREDITS

  Based on the 'du_multidirs-v2' initially written in Bash by Christian Kujau <lists@nerdbynature.de> and modified by dano229.
  This script was based on the 'homedirs' plugin, initially written in Perl by Philipp Gruber <pg@flupps.net>

=head1 MAGIC MARKERS

  #%# family=auto
  #%# capabilities=autoconf

=head1 LICENSE

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.

=cut

use warnings;
use strict;
use Munin::Plugin;
use POSIX qw(setsid);

my $PLUGIN_NAME = "du";
my $CACHEFILE="$Munin::Plugin::pluginstatedir/du.cache";
my $TEMPFILE="$Munin::Plugin::pluginstatedir/du.tmp";
my $LOCKFILE="$Munin::Plugin::pluginstatedir/du.lock";
my $TIMEFILE="$Munin::Plugin::pluginstatedir/du.time";

##### autoconf
if( (defined $ARGV[0]) && ($ARGV[0] eq "autoconf") ) {
    print "yes\n";
    ## Done !
    munin_exit_done();
}

## In the parent, it's just a regular munin plugin which reads a file with the infos
##### config
if( (defined $ARGV[0]) && ($ARGV[0] eq "config") ) {
    print "graph_title Directory usage\n";
    print "graph_args --base 1024 -l 1\n";
    print "graph_vlabel Bytes\n";
    print "graph_category disk\n";
    print "graph_total total\n";
    print "graph_info This graph shows the size of several directories\n";

    my $foo = 0;
    open (FILE, "<", $CACHEFILE) or munin_exit_fail();
    while(defined (my $bar = <FILE>)) {
        if ($bar =~ m/(\d+)\s+(.+)/) {
            my $dir = $2;
            clean_path(\$dir);
            print "$dir.label $dir\n";
            if ($foo++) {
                print "$dir.draw STACK\n";
            } else {
                print "$dir.draw AREA\n";
            }
        }
    }
    close(FILE);
    ## Done !
    munin_exit_done();
}

##### fetch
open (FILE, "<", $CACHEFILE) or munin_exit_fail();
while(defined (my $foo = <FILE>)) {
    if ($foo =~ m/(\d+)\s+(.+)/) {
        my ($field, $value) = ($2, $1);
        clean_path(\$field);
        print $field, ".value ", $value, "\n";
    }
}
close(FILE);
daemonize();

#
##
### PUBLIC FONCTIONS
###############################################################################
## Used to create the fork
sub daemonize {
    chdir '/'               or die "Can't chdir to /: $!";
    defined(my $pid = fork) or die "Can't fork: $!";
    munin_exit_done() if $pid;
    open STDIN, '/dev/null' or die "Can't read /dev/null: $!";
    open STDOUT, '>/dev/null' or die "Can't write to /dev/null: $!";
    open STDERR, '>&STDOUT' or die "Can't dup stdout: $!";
    setsid                  or die "Can't start a new session: $!";
    ## In the child, let's get the du infos if necessary
    if (cache_is_too_old() && du_not_running()) {
        my $dirs = $ENV{dirs};
        system("touch $LOCKFILE; du -sb $dirs > $TEMPFILE; cat $TEMPFILE > $CACHEFILE; rm $LOCKFILE; date +%s > $TIMEFILE;");
    }
    exit;
} ## daemonize

## Used to remove the beginning of the paths if wanted
sub clean_path {
    my ($path) = @_;
    if (defined $ENV{suppr}) {
        my $pattern = $ENV{suppr};
        $$path =~ s#^($pattern)##;
    }
} ## clean_path

## Do you really need I told you what this functions are going to check ?
sub cache_is_too_old {
    return 1 if (! -e $TIMEFILE);
    my ($time) = `cat $TIMEFILE`;
    chomp $time;
    return 1 if ( (time - $time) > ($ENV{interval}*60) );
    return 0;
} ## cache_is_too_old

sub du_not_running {
    if (-e $LOCKFILE) {
        my ($time) = `cat $TIMEFILE`;
        chomp $time;
        if ( (time - $time) > ($ENV{interval}*60*60) ) {
            # The cache is really old (60xinterval) => Maybe the lockfile wasn't properly deleted.
            # Let's delete it.
            system("rm $LOCKFILE;");
            return 1;
        } else {
	        return 0;
        }
    } else {
        return 1;
    }
}

sub munin_exit_done {
    __munin_exit(0);
} ## sub munin_exit_done

sub munin_exit_fail {
    __munin_exit(1);
} ## sub munin_exit_fail

#
##
### INTERNALS FONCTIONS
###############################################################################
sub __munin_exit {
    my $exitcode = shift;
    exit($exitcode) if(defined $exitcode);
    exit(1);
} ## sub __munin_exit