#!/usr/bin/perl 

# Gregg Lain  gregg @ MOCHABOMB . COM
# 2010-OCT-16 
#
# This script is distributable under the same terms as Perl itself.
#
# purgebinarylogs.pl - uses ~root/.my.cnf for root login info.

use strict;
use warnings;
use Getopt::Long;

my ($ok, $output, %mysqlprops, @lines, $purgeto, $query, $verbose, $purge, $back, $dir, $logbin) = undef;

# init
$verbose = $purge = $back = 0;
$dir = $logbin = "/tmp";

# exit if no arguments are passed
&Help unless (@ARGV);

my $results = GetOptions ( "v|verbose"         => \$verbose,
                           "p|purge"           => \$purge,
                           "d|dir=s"           => \$dir,
                           "h|help"            => \&Help,
                           "l|logbin=s"        => \$logbin,
                           "b|back=i"          => \$back);

# bail if options are not passed correctly
exit 1 unless ($results);

# set to defaults if not specified
$dir      = ($dir =~ /[\w\/\-]{4,}/)     ? $dir     : "/var/log/mysql";
$logbin   = ($logbin =~ /[\w\/\-]{9,}/)  ? $logbin  : "/var/log/mysql/log-bin.index";
$back     = ($back >= 1)                 ? $back    : 3;

# set these values
%mysqlprops = ( 'mysqldir' => $dir,
                'logbin-index' => $logbin,
                'files-to-keep' => $back );

# Get the log-bin file listing
open(INDEX, "<$mysqlprops{'logbin-index'}") or die "Cannot open $mysqlprops{'logbin-index'}\n";
@lines = <INDEX>;
chomp(@lines);
close INDEX;
my $n_lines = @lines;

print "Go back $back with $n_lines binlogs\n" if ($verbose);

# Exit if trying to go further back than what is available
if (($n_lines !~ /\d+/) or ($n_lines <= ($back-1)) or ($back < 1)) {
   print "Cannot go back $back with only $n_lines binlogs\n";
   print "Purge option not set\n" unless ($purge);
   exit(1);
}

# Go back through the bottom of the array to get the one to purge to
# Gotta love negative indexes     :)
$purgeto = $lines[-$mysqlprops{'files-to-keep'}];

# Remove path...
$purgeto =~ s#^.*\/##;

print "Purge to: $purgeto\n" if ($verbose);

# Build the query
$query = 'mysql -e \'purge binary logs to "' . $purgeto . '"\'';
print "$query\n" if ($verbose);

# If this runs fine, lets purge on.
my $testquery = 'mysql -e "show binary logs"';
system("$testquery") == 0 or die "Test query $testquery failed\n";;

# Purge only if told to
if ($purge) {
   $output = `$query`;
   print "$output\n" if ($verbose);
}

print "\n------- After purging -------\n" if ($verbose);

# else tell what would have happened
if ($purge != 1) {
  print "Purge option \"-p\" not set, would have used \n" . $query . "\n";
}

# details .. details
if ($verbose) {
   # Get the file listing again, print out..
   open(INDEX, "<$mysqlprops{'logbin-index'}") or die "Cannot open $mysqlprops{'logbin-index'}\n";
   @lines = <INDEX>;
   close INDEX;
   
   system("$testquery");
   # Build and Print the new log listing...
   $output .= "Bin Logs:\n";
   foreach (@lines) {$output .= `ls -la $_`;}
   print $output;
}

sub Help {
   print << "FINI";

   purgebinarylogs.pl - simple MySQL binary log purging..

      It goes back N files and purges to that point.
      Its good to make sure your slave queries are caught up before purging logs.  

   WHY
      I was manually purging logs every 3-4 weeks when disk space was getting 
      used up.  This alleviates this task...

      Uses the ~/my.cnf file for login information.  This was written to run 
      on Linux/Unix machines.

   USE
     -v  -verbose   verbose output
     -d  -dir       default is /var/log/mysql
     -l  -logbin    default is /var/log/mysql/log-bin.index
     -p  -purge     purge the logs
     -b  -back      logs to keep; default is 3
     -h  -help      print this help

     0. Configure the \%mysqlprops as needed or use command line options
     1. Its good to have backups of the binary logs in case things go wrong.
     2. run purgebinarylogs.pl -p to purge

        sample crontab entry 
        # purge binary logs - the two lines below need to be one line in crontab
        17 */2 * * * /usr/local/bin/purgebinarylogs.pl -b 7 -p -v 
                       >> /var/log/purgebinarylogs.log 2>&1;

     3. To adjust binlog file sizes, see mysql docs for max_binlog_size 

   Please send feedback to gregg at mochabomb daht com
   
   USE AT YOUR OWN RISK!

   No warranties express or implied.  If this deletes all your data and 
   your shiny Mercedes gets repossesed, I apologize. You have been warned.

FINI
exit 0;

}