You have an environment that is terminating SSL on the load balancer for one reason or another. Your application, such as WordPress or Magento, is configured to force SSL. But when you go to test out the site or the admin portal, you get a redirect loop. What happened?
This is a very common issue. In most cases when you are terminating SSL at the load balancer, the load balancer will send the traffic over to your web server using HTTP. This can confuse the web application since it was expecting it to be over HTTPS, and the application will not be able to tell that the client’s browser was in fact using HTTPS, which will result in a redirect loop.
The solution to this is actually very simple. You need to ask your load balancer to send the X-Forwarded-Proto header. This can easily be done by adding a SetEnvIf directive into your .htaccess (assuming Apache here), which will set the header to be what your application was expecting.
To account for this, at the top of your site’s .htaccess file, add the following:
[root@web01 ~]# vim /var/www/vhosts/www.domain.com/.htaccess ... # Detect the LB header and set the header accordingly for the application SetEnvIf X-Forwarded-Proto https HTTPS=on ...
So in summary, this will prevent your application from getting confused regarding if the connection originated over HTTP or HTTPS since the load balancer is handling the SSL termination, not the server.