3. custom template: when more specific settings are required, like [open_file_cache](http://nginx.org/en/docs/http/ngx_http_core_module.html#open_file_cache), custom [log_format](http://nginx.org/en/docs/http/ngx_http_log_module.html#log_format), adjust [listen](http://nginx.org/en/docs/http/ngx_http_core_module.html#listen) options as `rcvbuf` or when is not possible to change an through the ConfigMap.
NGINX exposes some flags in the [upstream configuration](http://nginx.org/en/docs/http/ngx_http_upstream_module.html#upstream) that enable the configuration of each server in the upstream. The Ingress controller allows custom `max_fails` and `fail_timeout` parameters in a global context using `upstream-max-fails` and `upstream-fail-timeout` in the NGINX ConfigMap or in a particular Ingress rule. `upstream-max-fails` defaults to 0. This means NGINX will respect the container's `readinessProbe` if it is defined. If there is no probe and no values for `upstream-max-fails` NGINX will continue to send traffic to the container.
**With the default configuration NGINX will not health check your backends. Whenever the endpoints controller notices a readiness probe failure, that pod's IP will be removed from the list of endpoints. This will trigger the NGINX controller to also remove it from the upstreams.**
`ingress.kubernetes.io/upstream-max-fails`: number of unsuccessful attempts to communicate with the server that should occur in the duration set by the `upstream-fail-timeout` parameter to consider the server unavailable.
`ingress.kubernetes.io/upstream-fail-timeout`: time in seconds during which the specified number of unsuccessful attempts to communicate with the server should occur to consider the server unavailable. This is also the period of time the server will be considered unavailable.
In NGINX, backend server pools are called "[upstreams](http://nginx.org/en/docs/http/ngx_http_upstream_module.html)". Each upstream contains the endpoints for a service. An upstream is created for each service that has Ingress rules defined.
**Important:** All Ingress rules using the same service will use the same upstream. Only one of the Ingress rules should define annotations to configure the upstream servers.
Is possible to add authentication adding additional annotations in the Ingress rule. The source of the authentication is a secret that contains usernames and passwords inside the the key `auth`
To use an existing service that provides authentication the Ingress rule can be annotated with `ingress.kubernetes.io/auth-url` to indicate the URL where the HTTP request should be sent.
Additionally it is possible to set `ingress.kubernetes.io/auth-method` to specify the HTTP method to use (GET or POST) and `ingress.kubernetes.io/auth-send-body` to true or false (default).
In some scenarios the exposed URL in the backend service differs from the specified path in the Ingress rule. Without a rewrite any request will return 404.
If the application contains relative links it is possible to add an additional annotation `ingress.kubernetes.io/add-base-url` that will prepend a [`base` tag](https://developer.mozilla.org/en/docs/Web/HTML/Element/base) in the header of the returned HTML from the backend.
The annotations `ingress.kubernetes.io/limit-connections` and `ingress.kubernetes.io/limit-rps` define a limit on the connections that can be opened by a single client IP address. This can be used to mitigate [DDoS Attacks](https://www.nginx.com/blog/mitigating-ddos-attacks-with-nginx-and-nginx-plus).
By default NGINX uses `http` to reach the services. Adding the annotation `ingress.kubernetes.io/secure-backends: "true"` in the Ingress rule changes the protocol to `https`.
### Server-side HTTPS enforcement through redirect
By default the controller redirects (301) to `HTTPS` if TLS is enabled for that ingress. If you want to disable that behaviour globally, you can use `ssl-redirect: "false"` in the NGINX config map
To configure this feature for specific ingress resources, you can use the `ingress.kubernetes.io/ssl-redirect: "false"` annotation in the particular resource
You can specify the allowed client IP source ranges through the `ingress.kubernetes.io/whitelist-source-range` annotation. The value is a comma separated list of [CIDRs](https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing), e.g. `10.0.0.0/24,172.10.0.1`.
**body-size:** Sets the maximum allowed size of the client request body. See NGINX [client_max_body_size](http://nginx.org/en/docs/http/ngx_http_core_module.html#client_max_body_size).
**custom-http-errors:** Enables which HTTP codes should be passed for processing with the [error_page directive](http://nginx.org/en/docs/http/ngx_http_core_module.html#error_page).
Setting at least one code also enables [proxy_intercept_errors](http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_intercept_errors) which are required to process error_page.
**enable-sticky-sessions:** Enables sticky sessions using cookies. This is provided by [nginx-sticky-module-ng](https://bitbucket.org/nginx-goodies/nginx-sticky-module-ng) module.
**enable-vts-status:** Allows the replacement of the default status page with a third party module named [nginx-module-vts](https://github.com/vozlt/nginx-module-vts).
HTTP Strict Transport Security (often abbreviated as HSTS) is a security feature (HTTP header) that tell browsers that it should only be communicated with using HTTPS, instead of using HTTP. It provides protection against protocol downgrade attacks and cookie theft.
**max-worker-connections:** Sets the maximum number of simultaneous connections that can be opened by each [worker process](http://nginx.org/en/docs/ngx_core_module.html#worker_connections).
**proxy-buffer-size:** Sets the size of the buffer used for [reading the first part of the response](http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_buffer_size) received from the proxied server. This part usually contains a small response header.`
**proxy-connect-timeout:** Sets the timeout for [establishing a connection with a proxied server](http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_connect_timeout). It should be noted that this timeout cannot usually exceed 75 seconds.
**proxy-read-timeout:** Sets the timeout in seconds for [reading a response from the proxied server](http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_read_timeout). The timeout is set only between two successive read operations, not for the transmission of the whole response.
**proxy-send-timeout:** Sets the timeout in seconds for [transmitting a request to the proxied server](http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_send_timeout). The timeout is set only between two successive write operations, not for the transmission of the whole request.
**server-name-hash-max-size:** Sets the maximum size of the [server names hash tables](http://nginx.org/en/docs/http/ngx_http_core_module.html#server_names_hash_max_size) used in server names, map directive’s values, MIME types, names of request header strings, etc.
**map-hash-bucket-size:** Sets the bucket size for the [map variables hash tables](http://nginx.org/en/docs/http/ngx_http_map_module.html#map_hash_bucket_size). The details of setting up hash tables are provided in a separate [document](http://nginx.org/en/docs/hash.html)
**ssl-ciphers:** Sets the [ciphers](http://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_ciphers) list to enable. The ciphers are specified in the format understood by the OpenSSL library.
The ordering of a ciphersuite is very important because it decides which algorithms are going to be selected in priority.
The recommendation above prioritizes algorithms that provide perfect [forward secrecy](https://wiki.mozilla.org/Security/Server_Side_TLS#Forward_Secrecy).
**ssl-session-cache:** Enables or disables the use of shared [SSL cache](http://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_session_cache) among worker processes.
**ssl-session-cache-size:** Sets the size of the [SSL shared session cache](http://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_session_cache) between all worker processes.
**ssl-session-tickets:** Enables or disables session resumption through [TLS session tickets](http://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_session_tickets).
**ssl-session-timeout:** Sets the time during which a client may [reuse the session](http://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_session_timeout) parameters stored in a cache.
**upstream-max-fails:** Sets the number of unsuccessful attempts to communicate with the [server](http://nginx.org/en/docs/http/ngx_http_upstream_module.html#upstream) that should happen in the duration set by the `fail_timeout` parameter to consider the server unavailable.
**upstream-fail-timeout:** Sets the time during which the specified number of unsuccessful attempts to communicate with the [server](http://nginx.org/en/docs/http/ngx_http_upstream_module.html#upstream) should happen to consider the server unavailable.
The default mime type list to compress is: `application/atom+xml application/javascript aplication/x-javascript application/json application/rss+xml application/vnd.ms-fontobject application/x-font-ttf application/x-web-app-manifest+json application/xhtml+xml application/xml font/opentype image/svg+xml image/x-icon text/css text/plain text/x-component`.
**use-proxy-protocol:** Enables or disables the [PROXY protocol](https://www.nginx.com/resources/admin-guide/proxy-protocol/) to receive client connection (real IP address) information passed through proxy servers and load balancers such as HAProxy and Amazon Elastic Load Balancer (ELB).
**worker-processes:** Sets the number of [worker processes](http://nginx.org/en/docs/ngx_core_module.html#worker_processes). The default of "auto" means number of available CPU cores.
The only requirement to avoid the close of connections is the increase of the values of `proxy-read-timeout` and `proxy-send-timeout`. The default value of this settings is `30 seconds`.
A more adequate value to support websockets is a value higher than one hour (`3600`).
NGINX provides the configuration option [ssl_buffer_size](http://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_buffer_size) to allow the optimization of the TLS record size. This improves the [Time To First Byte](https://www.igvita.com/2013/12/16/optimizing-nginx-tls-time-to-first-byte/) (TTTFB). The default value in the Ingress controller is `4k` (NGINX default is `16k`).
