Work with Capacity Reservation groups

You can use Amazon Resource Groups to create logical collections of Capacity Reservations, called resource groups. A resource group is a logical grouping of Amazon resources that are all in the same Amazon Region. For more information about resource groups, see What are resource groups? in the Amazon Resource Groups User Guide.

You can include Capacity Reservations that you own in your account, and Capacity Reservations that are shared with you by other Amazon accounts in a single resource group. You can also include Capacity Reservations that have different attributes (instance type, platform, Availability Zone, and tenancy) in a single resource group.

When you create resource groups for Capacity Reservations, you can target instances to a group of Capacity Reservations instead of an individual Capacity Reservation. Instances that target a group of Capacity Reservations match with any Capacity Reservation in the group that has matching attributes (instance type, platform, Availability Zone, and tenancy) and available capacity. If the group does not have a Capacity Reservation with matching attributes and available capacity, the instances run using On-Demand capacity. If a matching Capacity Reservation is added to the targeted group at a later stage, the instance is automatically matched with and moved into its reserved capacity.

To prevent unintended use of Capacity Reservations in a group, configure the Capacity Reservations in the group to accept only instances that explicitly target the capacity reservation. To do this, set Instance eligibility to targeted (old console) or Only instances that specify this reservation (new console) when creating the Capacity Reservation using the Amazon EC2 console. When using the Amazon CLI, specify --instance-match-criteria targeted when creating the Capacity Reservation. Doing this ensures that only instances that explicitly target the group, or a Capacity Reservation in the group, can run in the group.

If a Capacity Reservation in a group is canceled or expires while it has running instances, the instances are automatically moved to another Capacity Reservation in the group that has matching attributes and available capacity. If there are no remaining Capacity Reservations in the group that have matching attributes and available capacity, the instances run in On-Demand capacity. If a matching Capacity Reservation is added to the targeted group at a later stage, the instance is automatically moved into its reserved capacity.