Accessing form parameters 

my $app = sub {
    my($env) = @_;

    my $req = Plack::Request->new($env);

    my $path      = $req->path;
    my $client_ip = $req->address;

    if($req->method eq 'POST') {
        my $surname = $req->param('surname');
        my @hobbies = $req->param('hobby');
        ...
    }
};