just out of the sake of boredom and insanity, I was asked to setup load balancing here for a server at work. and I instantly fired up a pico session and starting hacking away at some perl :)
now, what they actually wanted me to do was email a guy and setup a round robin DNS, but of course, in my delirious, sick state I began a script to do load balancing in perl.
here's what I hacked out: (I plan on developing this to be a really kick ass system, but right now, its basic and it works)
#!/usr/bin/perl
# This is going to be fun..
# anyways.. code by me..
# Brad Lhotsky
# <brad@divisionbyzero.net>
#
use Socket;
use Symbol;
use Time::localtime;
use strict;

my $port = 8080;
my %CONF = {};
my $cfgfile = "balance.cfg";
my $DATADIR = "/home/blhotsky/code/load/data/";

%CONF = &readconf($cfgfile);

my ($crap,$things);
foreach $crap (keys(%CONF))
{
        print "$crap\n";
        foreach $things (@{$CONF{$crap}})
        {
                print "\t$things\n";
        }
}

socket(SERVER, AF_INET, SOCK_STREAM, getprotobyname('tcp')) || die $!;
setsockopt(SERVER, SOL_SOCKET, SO_REUSEADDR, 1); select SERVER; $|++; 
+select('stdout');
my $sin = sockaddr_in($port, INADDR_ANY);
bind(SERVER, $sin) || die $!;
listen(SERVER, SOMAXCONN);

while(1) 
{
  my $socket = gensym();
  accept($socket, SERVER);
  select $socket; $|++; select('stdout');
  my $get = <$socket>;
  chomp $get;
  my ($null, $url,$opts);
  ($null, $url,$null) = split(/\s/,$get);
  ($url, $opts) = split(/\?/, $url);
  &print_header($socket);
  my $redirect = &balance($url);
  if($opts) { $redirect .= "?$opts"; }
  $redirect .= "\n\n";
  print $socket $redirect;
  close $socket;
}

sub readconf {
        my $file = shift;
        die "no conf file!\n" if !$file;
        open(FILE, "< $file") || die "could not open $file\n";
        my %HASH;
        my $link;
        while(<FILE>)
        {
                s/^\s+//;
                chomp;
                next if /^$/;
                next if /^\#/;
                my($line,$comment) = split /\#/, $_;
                if(($line !~ /^:/) && !$link) { next; }
                if($line =~ /^:(.*)/) { $link = $1; $HASH{$link} = ();
+ next; }
                # If we get here, we need to push stuff into the hashe
+s anon array.
                $line =~ s/\s+$//;
                push @{$HASH{$link}}, $line;
        }
        return %HASH;
}

sub balance { 
        my $url = shift;
        if($url eq '/') { $url = "index.html"; }
        else { $url =~ s%^/%%; }
        if(!$url) { die "dammit no url to go to!\n"; }
        my $redirect;
        my $index = &getindex($url);
        if($CONF{$url}) { $redirect = $CONF{$url}->[$index]; }
        else { $redirect = "http://divisionbyzero.net/~trilex/index.ht
+ml"; }
        $redirect = "Location: $redirect\n\n";
        return $redirect;
}
sub print_header {
        my $socket = shift;
        if(!$socket) { die "no socket dumbass!\n"; }
        my $date = "Date: " . ctime() . " EST\n";
        my $headers = "HTTP/1.1 302 Found\n" . $date . "Server: Funky 
+Load Balancer/0.0.1 (Unix) Perl\n" . "Connection: close\n";
        print $socket $headers;
}

sub getindex {
        my $url = shift;
        if(!$url) { die "dammit no url to go to!\n"; }
        open(DATA, "<$DATADIR/$url") || sub { &datahandle($url); retur
+n 0; };
        my $line = <DATA>;
        close DATA;
        chomp $line;
        $line =~ s/\D+//g;
        &datahandle($url,$line);
        return $line;
}

sub datahandle {
        my $url = shift;
        my $num = shift;
        my $file = "$DATADIR/$url";
        $num++;
        if($num > $#{$CONF{$url}}) { $num = "0"; }
        if(!$url) { die "how the hell did this die?"; }
        open(DATA, ">$file") || die "this is not good no permissions i
+n $DATADIR\n";
        print DATA "$num\n";
        close DATA;
}

and here's the config file:
#######################
# Load Balancing conf file.
# format:
# :file   # absolute path from the server dir
#       http://some.domain.com/path/to/file
#       http://some.domain2.com/path/to/file
# :file2 
#       http://some.domain.com/path/to/file2
#       http://some.domain2.com/path/to/file2
:dbz
http://divisionbyzero.net/index.html
http://spark.divisionbyzero.net/index.html

:funky
http://ackers.net/index.html
http://realms.divisionbyzero.net/index.html

[download]


-brad..

In reply to Load Balancing fun.. by reyjrar

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