title: Always check for Shibboleth login without redirecting
body: <p>I am writing a Symfony app that has a firewall that uses Shibboleth as its SSO. The way it works is it looks to the environment variable REMOTE_USER and if it exists, it knows its logged in and sets up the user in a custom user provider.</p>
  
  <p>The issue: Environment variables are only valid for the 1 request, so it it constantly looking to Shibboleth to check it's logged in.</p>
  
  <p>So I somehow need to get the environment variables to exist before the start of the page load (if the user is logged in). So is there a way to get Apache (on RedHat) to look to Shibboleth for details, but if not logged in, not redirect to the login?</p>