We're seeing heavy load from CORS preflight requests which are OPTIONS requests. We already cache HEAD and GET requests with the ngx_http_fastcgi_module nginx module.

But if we add fastcgi_cache_methods GET HEAD OPTIONS; nginx refuses to start

nginx: [emerg] invalid value "OPTIONS" in /etc/nginx/nginx.conf:120
nginx: configuration file /etc/nginx/nginx.conf test failed

Doesn't nginx support caching OPTIONS requests?