gistfile1.perl

$app = ...;
if (my $map = $self->config->proxy_map) {
    my $urlmap = Plack::App::URLMap->new;
    for my $type (keys %$map) {
        my ($prefix, $remote, $headers) =
            @{$map->{$type}}{qw(path_prefix remote headers)};
        $headers ||= {};
        my $proxy = Plack::App::Proxy->new(
            remote => $remote,
            preserve_host_header => 1,
        )->to_app;
        $urlmap->mount($prefix => sub {
            my $env = shift;
            return $proxy->({ %$env, %$headers });
        });
    }
    $urlmap->mount('/' => $app);
    $app = $urlmap->to_app;
}