Merge pull request #296040 from craigshoemaker/aca/scaling-overview-update

[Container Apps] Update: Scaling overview

Author: prmerger-automator[bot]

articles/container-apps/scale-app.md

@@ -6,7 +6,7 @@ author: craigshoemaker
 ms.service: azure-container-apps
 ms.custom: devx-track-azurecli
 ms.topic: conceptual
-ms.date: 02/10/2025
+ms.date: 03/07/2025
 ms.author: cshoe
 zone_pivot_groups: arm-azure-cli-portal
 ---
@@ -15,6 +15,8 @@ zone_pivot_groups: arm-azure-cli-portal
 
 Azure Container Apps manages automatic horizontal scaling through a set of declarative scaling rules. As a container app revision scales out, new instances of the revision are created on-demand. These instances are known as replicas.
 
+To support this scaling behavior, Azure Container Apps is powered by KEDA (Kubernetes Event-driven Autoscaling). KEDA supports scaling against a variety of metrics like HTTP requests, queue messages, CPU and memory load, and event sources like Azure Service Bus, Azure Event Hubs, Apache Kafka, and Redis. For more information, see [Scalers in the KEDA documentation](https://keda.sh/docs/scalers/).
+
 Adding or editing scaling rules creates a new revision of your container app. A revision is an immutable snapshot of your container app. To learn which types of changes trigger a new revision, see revision [change types](./revisions.md#change-types).
 
 [Event-driven Container Apps jobs](jobs.md#event-driven-jobs) use scaling rules to trigger executions based on events.
@@ -50,7 +52,10 @@ Scaling is driven by three different categories of triggers:
 
 - [HTTP](#http): Based on the number of concurrent HTTP requests to your revision.
 - [TCP](#tcp): Based on the number of concurrent TCP connections to your revision.
-- [Custom](#custom): Based on CPU, memory, or supported event-driven data sources such as:
+- [Custom](#custom): Based on custom metrics like:
+  - CPU
+  - Memory
+  - Supported event-driven data sources:
     - Azure Service Bus
     - Azure Event Hubs
     - Apache Kafka