How to Set return of perl function in request header using nginx

Could anyone help me with nginx with a perl module?
I have already managed to create a function in Perl using the ubi8/nginx-124 image but I am not able to set the result of the function in the header.

Having this in nginx configuration file:

http {
   perl_modules /opt/app-root/etc/nginx/nginx-perl/;
   perl_require module1.pm;
   perl_set $test module1::handler; #it is not calling the function here, it is only called in the location block
}
location = /perl {
    perl module1::handler; #I've already tried with and without this line
    add_header X-My-Header $test; #I tried adding the header this way and from within the code with $r.But both without success
}

and this perl file:

package module1;;

use nginx;
sub handler {
    my $r = shift;
    my $foo = 'foo';

    $r->send_http_header("text/html");
    $r->header_out("WWW-Authenticate" => $foo);

    $r->print("SUCCESS:");
    return $foo;
}
1;