title: Problems with Memory and CPU limits in AWS ECS cluster running on reserved EC2 instance
body: <p>I am running the ECS cluster that currently has 3 services running on T3 medium instance. Each of those services is running only one task which has a soft memory limit of 1GB, the hard limit is different for each (but that should not be the problem). I will always have enough memory to run one, new deployed task (new one will also take 1GB, and T3 medium will be able to handle it since it has 4GB total). After the new task is up and running, the old one will be stopped and I will have again 1GB free for the new deployment. I did similar to the CPU (2048 CPU, each task has 512, and 512 free for new deployments). </p>
  
  <p>So everything runs fine now, but I am not completely satisfied with this setup for the future. What will happen if I need to add another service with another task? I need to deploy all existing tasks and to modify their task definitions to use less CPU and memory in order to run this new task (and new deployments). I am planning to get a reserved EC2 instance, so it will not be easy to swap the current EC2 instance with the larger one. </p>
  
  <p>Is there a way to spin up another EC2 instance for the same ECS cluster to handle bursts in my tasks? Also deployments, it's not a perfect scenario to have the ability to deploy only one task, and then wait for old to be killed in order to deploy the next one, without downtimes.
  And biggest concern, what if I need new service and task, I need again to adjust all others in order to run a new one and deploy others, which is not very maintainable and what if I cannot lower CPU and memory more because I already reached the lowest point in order to run the task smoothly.</p>
  
  <p>I was thinking about having another EC2 instance for the same cluster, that will handle bursts, deployments, and new services/tasks. But not sure if that's possible and if that's the best way of doing this. I was also thinking about Fargate, but this is much more expensive and I cannot afford it for now. What do you think? Any ideas, suggestions, and hints will be helpful since I am desperate to find the best way to avoid the problems mentioned above. </p>
  
  <p>Thanks in advance!</p>