Use session.

lib/MyApp/Controller/Auth.pm

@@ -6,8 +6,10 @@ sub index ($self) {
 
 sub login ($self) {
    my $logname = $self->param('logname');
+   $self->session(logname => $logname);
+   $self->redirect_to('/');
    # The text isn't escaped.
-   $self->render(text => "You logged in as $logname");
+#   $self->render(text => "You logged in as $logname");
 }
 
 1;

templates/index.html.ep

@@ -2,7 +2,11 @@
 % title 'Welcome';
 <h1>Welcome to the Mojolicious real-time web framework!</h1>
 
-This was expanded from a template.
+<% if (session('logname')) { %>
+You are logged in as <%= session 'logname' %>.
+<% } else { %>
+You are not logged in.
+<% } %>
 
 <p>Other pages:</p>