title: ECS deployment and matching number of running tasks
body: <p>Scenario:
  ECS Fargate.<br />
  Say I have a “desired count” of 2 tasks.</p>
  <p>The system takes on some load and auto scales to 6 tasks.</p>
  <p>If I deploy during this time, ECS seems to kill off my actual running capacity back down to 2 tasks. This causes service failures b/c the system can no longer handle the actual load and must now scale back up.
  All the docs I’ve come across indicate using “minimum healthy percent” and “maximum percent” to help control deployment sizes, but these refer back do the DESIRED count of tasks, not the actual number running on the actual system being deployed to.</p>
  <p>Any idea if there is a way to say: “please just match the number of tasks running, or some percentage of such when spinning up new tasks from deploy”?</p>
  <p>Deploy is Cloudformation via CodePipeline.</p>