Plack provides an excellent way to add various middlewares to the stack serving the application. One of the middlewares is called Plack::Middleware::Static and its purpose is, not surprisingly, to server static files.

First we need to have the static files on our disk. We will store them in a subdirectory of the project called 'static':

$ mkdir static
$ cd static
$ wget http://search.cpan.org/favicon.ico

You could see the favicon.ico here too.

We also create a file called static/robots.txt with the following content:

User-agent: *
Disallow: /

The thing is, at this point we would like to avoid being indexed by any of the search engines. We don't want the site to be seen by any of the search engines and just a copy of search.cpan.org. That could cause damage to both sites.

Plack::Middleware::Static

In order to configure this middleware we need to use the builder function of Plack::Builder.

This is how the run subroutine looks like after the change:

Earlier it returned an anonymous subroutine we created and assigned to the $app variable. Back then I mentioned we did not even need to assign the function to this variable, but now it comes handy. We store the anonymous subroutine in the $app variable and then we use the builder function imported from the Plack::Builder to create and return a new anonymous function.

Inside the call to builder we configure the Plack::Middleware::Static. It basically needs two parameters: A regex that might match the path part of a URL in the site and a directory where the static files are located If the path_info part of the request matches the request, then the Static Middleware will try to load and serve that file from the given directory.

sub run {
    my $root = root();

    my $app = sub {
        my $env = shift;

        my $request = Plack::Request->new($env);
        if ($request->path_info eq '/') {
            return template('index');
        }

        return [ '404', [ 'Content-Type' => 'text/html' ], ['404 Not Found'], ];
    };

    builder {
        enable 'Plack::Middleware::Static',
            path => qr{^/(favicon.ico|robots.txt)},
            root => "$root/static/";
        $app;
    };
}

This code also needed the path to the root of the project we had in the template function. Instead of repeating that nasty piece of code (calling dirname 3 times), I factored it out to a separate function called root() so when time comes and we improve the way we compute the path to the root directory, it will be easier to update it in only one place.

This lead us to the next commit:

$ git add .
$ git commit -m "add static files: favicon taken from search.cpan.org and robots.txt that disallows every user-agent"