Amazon EC2/Spot Fleet now support modifying instance types and weights on the run

Posted on: Aug 31, 2020

You now have an option to modify instance types and weights for a running EC2 Fleet or Spot Fleet (referred to further as fleet). You can replace an entire launch template configuration specifying new instance types, weights, and other parameters without deleting and re-creating a fleet. 

You can use this feature to fully or partially replace instance types in a fleet without losing the current fleet ID. Fleet will use newly specified instance types to provision new instances as needed to fulfill target capacity. To speed up the replacement you can first scale in by setting a lower target capacity. Fleet will first shut down instances that use older AMIs. Then you can scale out by setting target capacity back to the previous or higher level. Fleet will provision instances using new instance types and weights until the new target capacity is reached. 

Amazon EC2 Fleet and Spot Fleet simplify provisioning of EC2 capacity across different EC2 instance types, Availability Zones, and purchase models (On-Demand, Reserved Instances, Savings Plans, and Spot), to optimize scale, performance and cost. To learn more about modifying launch template configs for a running EC2 Fleet please visit this page. To learn more about modifying launch template configs for a running Spot Fleet please visit this page.