ingress-nginx-helm/docs/user-guide/customizing-nginx.md

Customizing NGINX

There are three ways to customize NGINX:

1. ConfigMap: using a Configmap to set global configurations in NGINX.
2. Annotations: use this if you want a specific configuration for a particular Ingress rule.
3. Custom template: when more specific settings are required, like open_file_cache, adjust listen options as rcvbuf or when is not possible to change the configuration through the ConfigMap.