ALBRequestCountPerTarget auto-scaling metric not available on an ECS Service

Question

Hi, I'm trying to set my ECS service to scale up and down based on the ALBRequestCountPerTarget metric, but it's always greyed out. I can set the the average CPU or Memory metric just fine. I've been going over the documentation and the only information I can find on this metric is that it's only applies to spot fleets and ECS Services, which is where I'm trying to use it. There's no other indication I can see as to why it's not available for selection. The service in question is using the EC2 launch type in bridge network mode. It's associated to two target groups currently. Any help would be appreciated. Thanks!

Answer

Hi
 
The reason  the "ALBRequestCountPerTarget" option was greyed out was due to not having an application load balancer configured for the ECS cluster service.

>When configuring the service for the ECS cluster, you will need to specify the Application Load Balancer that will be used to distribute incoming traffic across the tasks running in your service [1].

>Once the Load balancer has be configured, you will  be able to Configure Service Auto Scaling to adjust your service’s desired count [2], then be able to select the “ALBRequestCountPerTarget” as the ‘ECS service metric’ on the target tracking scaling policy [2].
[1] https://docs.aws.amazon.com/AmazonECS/latest/developerguide/service-create-loadbalancer-rolling.html

[2] https://docs.aws.amazon.com/AmazonECS/latest/developerguide/service-configure-auto-scaling.html

ALBRequestCountPerTarget auto-scaling metric not available on an ECS Service

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