Example Boomerang custom variables with PHP to get request IP and User Agent, javascript to get domain.

example.php

/* http://lognormal.github.io/boomerang/doc/howtos/howto-5.html */

<script type="text/javascript">
BOOMR.init({
		beacon_url: "http://yoursite.com/path/to/beacon"
	});
	

var domain = location.hostname;

BOOMR.addVar({
  	"ip": "<? 
        if (getenv("HTTP_CLIENT_IP")) 
          $ip = getenv("HTTP_CLIENT_IP"); 
        else if(getenv("HTTP_X_FORWARDED_FOR")) 
          $ip = getenv("HTTP_X_FORWARDED_FOR"); 
        else if(getenv("REMOTE_ADDR")) 
          $ip = getenv("REMOTE_ADDR"); 
        else 
          $ip = "UNKNOWN";
        echo "$ip"; 
      ?>",
	"user_agent": "<?
        $browser_type = getenv("HTTP_USER_AGENT");
        echo "$browser_type";
      ?>",
      "domain": domain
	});
	
</script>