Merge pull request #43950 from kundan2707/configuration-snippet

Document annotation nginx.ingress.kubernetes.io/configuration-snippet

Author: k8s-ci-robot

content/en/docs/reference/labels-annotations-taints/_index.md

@@ -1209,6 +1209,24 @@ Used on: IngressClass
 When a IngressClass resource has this annotation set to `"true"`, new Ingress resource
 without a class specified will be assigned this default class.
 
+### nginx.ingress.kubernetes.io/configuration-snippet
+
+Type: Annotation
+
+Example: `nginx.ingress.kubernetes.io/configuration-snippet: "  more_set_headers \"Request-Id: $req_id\";\nmore_set_headers \"Example: 42\";\n"`
+
+Used on: Ingress
+
+You can use this annotation to set extra configuration on an Ingress that 
+uses the [NGINX Ingress Controller] (https://github.com/kubernetes/ingress-nginx/)
+The `configuration-snippet` annotation is ignored
+by default since version 1.9.0 of the ingress controller.
+The NGINX ingress controller setting `allow-snippet-annotations.` 
+has to be explicitly enabled to
+use this annotation.
+Enabling the annotation can be dangerous in a multi-tenant cluster, as it can lead people with otherwise
+limited permissions being able to retrieve all Secrets in the cluster.
+
 ### kubernetes.io/ingress.class (deprecated)
 
 Type: Annotation