Merge pull request #231961 from jaesoni/conn-draining-ws

Conn Draining revision

Author: prmerger-automator[bot]

articles/application-gateway/configuration-http-settings.md

@@ -5,7 +5,7 @@ services: application-gateway
 author: greg-lindsay
 ms.service: application-gateway
 ms.topic: conceptual
-ms.date: 09/13/2022
+ms.date: 03/17/2023
 ms.author: greglin
 ---
 
@@ -34,7 +34,12 @@ Please refer to TLS offload and End-to-End TLS documentation for Application Gat
 
 ## Connection draining
 
-Connection draining helps you gracefully remove backend pool members during planned service updates. It applies to backend instances that are explicitly removed from the backend pool or during scale-in of backend instances. You can apply this setting to all members of a backend pool by enabling connection draining on the Backend Setting. It ensures that all deregistering instances of a backend pool continue to maintain existing connections and serve on-going requests for a configurable timeout and don't receive any new requests or connections. 
+Connection draining helps you gracefully remove backend pool members during planned service updates. It applies to backend instances that are 
+- explicitly removed from the backend pool,
+- removed during scale-in operations, or
+- reported as unhealthy by the health probes.
+
+You can apply this setting to all backend pool members by enabling Connection Draining in the Backend Setting. It ensures that all deregistering instances in a backend pool don't receive any new requests/connections while maintaining the existing connections until the configured timeout value. This is also true for WebSocket connections.
 
 | Configuration Type  | Value |
 | ---------- | ---------- |

articles/application-gateway/features.md

@@ -5,7 +5,7 @@ services: application-gateway
 author: greg-lindsay
 ms.service: application-gateway
 ms.topic: conceptual
-ms.date: 09/13/2022
+ms.date: 03/17/2023
 ms.author: greglin
 ---
 
@@ -102,9 +102,14 @@ For more information, see [WebSocket support](application-gateway-websocket.md)
 
 ## Connection draining
 
-Connection draining helps you achieve graceful removal of backend pool members during planned service updates. This setting is enabled via the backend http setting and can be applied to all members of a backend pool during rule creation. Once enabled, Application Gateway ensures all deregistering instances of a backend pool don't receive any new request while allowing existing requests to complete within a configured time limit. This applies to both backend instances that are explicitly removed from the backend pool by a user configuration change, and backend instances that are reported as unhealthy as determined by the health probes. The only exception to this are requests bound for deregistering instances, which have been deregistered explicitly, because of gateway-managed session affinity and continues to be proxied to the deregistering instances.
+Connection draining helps you achieve graceful removal of backend pool members during planned service updates or problems with backend health. This setting is enabled via the [Backend Setting](configuration-http-settings.md) and is applied to all backend pool members during rule creation. Once enabled, the aplication gateway ensures all deregistering instances of a backend pool don't receive any new requests while allowing existing requests to complete within a configured time limit. It applies to cases where backend instances are
+- explicitly removed from the backend pool after a configuration change by a user,
+- reported as unhealthy by the health probes, or
+- removed during a scale-in operation.
 
-For more information, see [Application Gateway Configuration Overview](configuration-http-settings.md#connection-draining).
+The only exception is when requests continue to be proxied to the deregistering instances because of gateway-managed session affinity.
+
+The connection draining is honored for WebSocket connections as well. For information on time limits, see [Backend Settings configuration](configuration-http-settings.md#connection-draining).
 
 ## Custom error pages