I have set autoscale for an ECS service (fargate). It has run over night and now I wish to see a graph or any other history of the tasks count. Can't find this in ECS nor in cloudwatch. Any idea how?
If you are using CloudWatch Container Insights that will provide you with a view of task counts for your service (along many other metrics). See picture.
This has an additional cost though. It could be possible to build something ad-hoc to track the tasks that does not involve using Container Insights. For example, this is a small toy project I built to track ALL fargate tasks/pods running in a single account/region. You could possibly adapt it to only track a specific ECS service.