title: What is the advantage of using Spot Fleet Autoscaling instead of AutoScaling Groups with a Spot Price?
body: <p>Recently Amazon AWS released Auto Scaling for Spot Fleets (<a href="https://aws.amazon.com/blogs/aws/new-auto-scaling-for-ec2-spot-fleets/" rel="noreferrer">https://aws.amazon.com/blogs/aws/new-auto-scaling-for-ec2-spot-fleets/</a>).
  Auto Scaling groups already allowed you to set a Spot Price to get Spot Instances at a discount instead of Reserved Instances.</p>
  
  <p>As far as I could see Spot Fleets allow you to define the fleet capacity in terms of vCPU, mixing different instance types to achieve this. I don't think this can be done using Auto Scaling as far as I know.</p>
  
  <p>My use case is pretty simple: use Spot Fleets (or Auto Scaling with Spot instances) to increase the capacity of my cluster at a reduced price while keeping the minimum required Reserved Instances just in case. I could duplicate my ASG, set a spot price and I'd be done, but apparently this functionality now also exists as part of Spot Fleets.</p>
  
  <p>What is the advantage of one over the other? Are there any major reasons to switch?</p>