title: Session Expired on tomcat8 behind apache2 ProxyPass
body: <p>For a web application named whys written with VAADIN 7.3.8, i deployed a tomcat8 server behind an apache one (and redirected app.whys.fr to whys.fr:8080/Whys wich is my app location).</p>
  
  <p>When i go on <a href="http://whys.fr:8080/Whys" rel="nofollow">http://whys.fr:8080/Whys</a>, everything looks good, but when i go on <a href="http://app.whys.fr" rel="nofollow">http://app.whys.fr</a>, i get a session expired message immediatly, and no logs to tell me why (nothing in catalina.out).</p>
  
  <p>You can test it by your own to see the difference ;).</p>
  
  <p>Here is my proxy configuration :</p>
  
  <pre><code>&lt;VirtualHost *:80&gt;
    ServerName app.whys.fr
    ProxyRequests On
    ProxyPass / http://localhost:8080/Whys/
    ProxyPassReverse / http://localhost:8080/Whys/
          &lt;Proxy *&gt;
                  Order deny,allow
                  Allow from all
          &lt;/Proxy&gt;
  &lt;/VirtualHost&gt;
  
  &lt;VirtualHost *:80&gt;
    ServerName whys.fr
  &lt;/VirtualHost&gt;
  </code></pre>
  
  <p>and my tomcat Connector in server.xml:</p>
  
  <pre><code>&lt;Connector port="8080" protocol="HTTP/1.1"
                 connectionTimeout="20000"
                 redirectPort="8443" /&gt;
  </code></pre>
  
  <p>apache2 has mod_proxy,mod_proxy_http and mod_proxy_connect enabled, timeout for session in web.xml is 30 mins.</p>
  
  <p>EDIT: forgot to mention: my application is using @Push (vaadin feature)</p>