using a map for limit_re_zone directive

playbooks/roles/edxapp/defaults/main.yml

@@ -282,6 +282,7 @@ EDXAPP_ENABLE_RATE_LIMITING: false
 EDXAPP_COURSES_REQUEST_RATE: '5r/s'
 EDXAPP_COURSES_REQUEST_BURST_RATE: 10
 EDXAPP_COURSES_USER_AGENT_BURST_RATE: 5
+EDXAPP_COURSES_USER_AGENTS: []
 
 EDXAPP_LANG: 'en_US.UTF-8'
 EDXAPP_LANGUAGE_CODE : 'en'

playbooks/roles/nginx/templates/edx/app/nginx/sites-available/lms.j2

@@ -15,8 +15,13 @@ upstream lms-backend {
 # Make Zone
 limit_req_zone $cookie_{{ EDXAPP_SESSION_COOKIE_NAME }} zone=cookies:10m rate={{ EDXAPP_COURSES_REQUEST_RATE }};
 {% for agent in EDXAPP_COURSES_USER_AGENTS %}
-limit_req_zone {{ agent.agent_name }} $binary_remote_addr zone=agents:10m rate={{ agent.rate }};
+map $http_user_agent {{ "$limit_bot_" ~ agent.alias }} {
+          {{ agent.agent_name }} $binary_remote_addr;
+      }
+limit_req_zone {{ "$limit_bot_" ~ agent.alias }} zone=agents:10m rate={{ agent.rate }};
 {% endfor %}
+
+{%- endif %}
 {%- endif %}