Add AutoScaling Support

[hspencer77]

Feature Request

Feature request to add autoscaling support for ECS workloads deployed. Autoscaling support should be added for the following:

• CPU utilization - (ECS)
• Memory utilization - (ECS)
• Request Count Per Target (ALB)
• Target Response Time (ALB)
• HTTPCode_Target_3XX_Count, HTTPCode_Target_4XX_Count, HTTPCode_Target_5XX_Count (ALB)

Some additional ones that would be helpful:

• ApproximateNumberOfMessagesVisible (SQS)

Use Cases

• Autoscale ECS workloads based upon CPU/Memory metrics
• Autoscale ECS workloads based upon ALB metrics (this is helpful if a given workload deployed on ECS has a certain performance characteristic that would require a faster scaling out response instead of waiting for CPU/Memory on ECS to get to a specific level)
• Autoscale on SQS queue when X number of messages are visible (this would allow a ratio mapping of the number of ECS tasks per number of messages)

[JohnPreston]

Done for CPU/RAM.
Working on SQS based scaling so going to work on a merge of the two features.

[JohnPreston]

@hspencer77 SQS based step scaling is done. Further investigation and testing to be done but technically works.

[JohnPreston]

To do: LB based scaling.