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package Plack::Middleware::Proxy::LoadBalancer;
use strict;
use warnings;
use parent 'Plack::Middleware';
use Plack::Util::Accessor qw/backends/;
our $VERSION = '0.01';
sub new {
my $class = shift;
my %param = ref $_[0] ? %{ $_[0] } : @_;
my $backends = delete $param{backends};
my $self = $class->SUPER::new( \%param );
$self->_set_backends( $backends );
$self;
}
sub _set_backends{
my $self = shift;
my ( $backends ) = @_;
# A total of 'weight' should be 1.0
if( ref $backends eq 'ARRAY'){
my $weight = 1 / @$backends;
$self->backends([
map { {remote => $_, weight => $weight} } @$backends
]);
}elsif( ref $backends eq 'HASH'){
my $total = 0;
$total += $_ for values %$backends;
$self->backends([ map {
{remote => $_, weight => $backends->{$_} / $total}
} keys %$backends ]);
}else{
$self->backends([ { remote => $backends, weight => 1 } ]);
}
}
sub select_backend {
my $self = shift;
my $rand = rand;
my $choice = undef;
for( @{ $self->backends } ){
$choice = $_->{remote};
($rand -= $_->{weight}) <= 0 and last;
}
return $choice;
}
sub call {
my ( $self, $env ) = @_;
$env->{'plack.proxy.remote'} = $self->select_backend;
$self->app->($env);
}
1;
__END__
=head1 NAME
Plack::Middleware::Proxy::LoadBalancer - Simple load balancer
=head1 SYNOPSIS
use Plack::Builder;
use Plack::App::Proxy;
builder {
enable "Proxy::LoadBalancer", backends => ['http://10.0.0.1:8080', 'http://10.0.0.1:8081'];
Plack::App::Proxy->new()->to_app;
};
=head1 DESCRIPTION
Plack::Middleware::Proxy::LoadBalancer allow you to define several backends.
=head1 OPTIONS
=over 4
=item backends
enable "Proxy::LoadBalancer", backends => 'http://10.0.0.1:8080';
Or
enable "Proxy::LoadBalancer", backends => ['http://10.0.0.1:8080', 'http://10.0.0.1:8081'];
Or
enable "Proxy::LoadBalancer", backends => {'http://10.0.0.1:8080' => 0.4, 'http://10.0.0.1:8081' => 0.5, 'http://10.0.0.1:8002' => 0.3};
More than one backend can be defined. Weight can be given to backends.
=back
=head1 AUTHOR
Franck Cuny
=head1 SEE ALSO
L<Plack::App::Proxy>
=cut
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