roles/dspace: Add rate limit to more dynamic pages

No user agent should be legitimately making more than one request
every five seconds (12/m) to dynamic pages like browse or Discover.

roles/dspace/templates/nginx/default.conf.j2

@@ -102,6 +102,15 @@ server {
         }
     }
 
+    # rate limit requests to dynamic pages to protect against bots and malicious
+    # users (see the definition for the dynamicpages limit_req_zone later).
+    location ~ /(browse|discover|search-filter|most-popular) {
+        # rate limit for dynamic pages
+        limit_req zone=dynamicpages;
+
+        proxy_pass http://tomcat_http;
+    }
+
     # tell robots not to index or follow links on dynamic pages (because we can't use * in robots.txt!)
     # see: https://jira.duraspace.org/browse/DS-2962
     location ~ /handle/[0-9]+/[0-9]+/(browse|discover|search-filter|most-popular) {