title: How to map an action in grails 3 to "/"?
body: <p>I'm using Grails 3.3.10 and trying to map "/" to a controller action, where the user is redirected after a successful login.</p>
  
  <p>In UrlMappings I have:</p>
  
  <pre><code>class UrlMappings {
  
     static mappings = {
  
        "/"(controller:'app')
     ...
  ...
  </code></pre>
  
  <p>When the user signs in, the app is redirected to the root <a href="http://localhost:8090/" rel="nofollow noreferrer">http://localhost:8090/</a>, but it shows a generated view from Grails:</p>
  
  <pre><code>Welcome to Grails
  
  Congratulations, you have successfully started your first Grails
  application! At the moment this is the default page, feel free to
  modify it to either redirect to a controller or display whatever
  content you may choose. Below is a list of controllers that are
  currently deployed in this application, click on each to execute
  its default action:
  
  Available Controllers:
  
  ....
  </code></pre>
  
  <p>I deleted the default index.gsp and the main.gsp layout, but that view with the controllers is still appearing and I can't get my action to be executed.</p>
  
  <p>If I remove the UrlMapping "/"(controller:'app'), the action is executed OK and the view is the correct one, but the URL is <a href="http://localhost:8090/app/index" rel="nofollow noreferrer">http://localhost:8090/app/index</a></p>
  
  <p>Is it possible to display the view from app/index being the URL mapped to "/"?</p>