Make cache size a var

playbooks/roles/edxapp/defaults/main.yml

@@ -226,6 +226,7 @@ EDXAPP_CMS_SSL_NGINX_PORT: 48010
 EDXAPP_ENABLE_RATE_LIMITING: false
 EDXAPP_COURSE_REQUEST_RATE: '5r/s'
 EDXAPP_COURSE_REQUEST_BURST_RATE: 10
+EDXAPP_COURSES_REQUEST_CACHE_SIZE: 10m
 
 EDXAPP_LANG: 'en_US.UTF-8'
 EDXAPP_LANGUAGE_CODE : 'en'

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

@@ -13,7 +13,7 @@ upstream lms-backend {
 
 {%- if EDXAPP_ENABLE_RATE_LIMITING -%}
 # Make Zone
-limit_req_zone $cookie_{{ EDXAPP_SESSION_COOKIE_NAME }} zone=cookies:10m rate={{ EDXAPP_COURSES_REQUEST_RATE }};
+limit_req_zone $cookie_{{ EDXAPP_SESSION_COOKIE_NAME }} zone=cookies:{{ EDXAPP_COURSES_REQUEST_CACHE_SIZE }} rate={{ EDXAPP_COURSES_REQUEST_RATE }};
 {%- endif %}