Spot Placement Score (SPS)

As Spot capacity fluctuates, you can’t be sure that you’ll always get the capacity that you need. The Spot placement score feature can recommend an AWS Region(s) or Availability Zone(s) where you can run the workload based on your Spot capacity requirements. The Spot placement score gives the Region(s) or Availability Zone(s) a score of 1 to 10 indicating how likely a Spot request will succeed. A score of 10 indicates that your Spot request is highly likely—but not guaranteed—to succeed, and a score of 1 indicates that your Spot request is not likely to succeed at all. For SPS to return a meaningful score, the SPS request must be configured with at least three instance types.

You can calculate a Spot placement score by using the Amazon EC2 console or the AWS CLI.

The same Spot placement score request can yield different scores for the same Regions or Availability Zones when calculated at different times. The same Spot placement score might be returned for different Regions or Availability Zones.

Spot placement score can be used to

  • determine the ability to relocate and scale Spot compute capacity in a different region if the workload is region flexible
  • identify the most optimal Availability Zone to run the single Availability Zone workloads
  • find an optimal configuration that will fulfill the Spot capacity needs

Using Amazon EC2 console to calculate Spot placement score

  1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
  2. In the navigation pane, choose Spot Requests.
  3. Choose Spot placement score in the top right corner.

Provide the inputs as show below:

Spot placement score request

A sample output of the response on the console is show below:

Spot placement score request

Using AWS CLI to calculate Spot placement score

You can use a json file that includes the parameters for running a Spot placement score request.

To get started, specify the target Spot capacity, as vCPUs or memory in MiB or in units. By specifying your target capacity in terms of the number of vCPUs or the amount of memory, you can use these units when counting the total capacity. For example, when mixing instances of different sizes, you can specify the target capacity in terms of total memory. Instances of different sizes are considered based on its memory rather than total number of instances when totaling up the target capacity.

Specify instance attributes or instance types. If instances can be selected based on attributes, you can use attribute-based instance type selection to specify your compute needs. If you need to use specific instances types for your workload, specify these instance types. In both cases, ensure that your request for Spot capacity includes at least a minimum of three instance types in the request.

cat <<EoF > ./sps-input.json
{
    "InstanceRequirementsWithMetadata": {
        "ArchitectureTypes": [
            "x86_64"
        ],
        "InstanceRequirements": {
            "VCpuCount": {
                "Min": 4,
                "Max": 8
            },
            "MemoryMiB": {
                "Min": 16384
            }
        }
    },
    "TargetCapacity": 100,
    "TargetCapacityUnitType": "vcpu",
    "SingleAvailabilityZone": false
}
EoF

In the above example, we will be running a Spot placement score for 10K vCPUs using any x86 architecture instance which has a vCPU between 4 and 8 and Memory greater than 16MB. To run the Spot placement score request with the above parameters, use this command.

aws ec2 get-spot-placement-scores --cli-input-json file://./sps-input.json

Spot placement score returns the top 10 regions or top 10 Availability Zones where the specific Spot request is most likely to succeed. You can narrow down the Regions to be considered in the response. You can combine the Region filter and a request for scored Availability Zones to return a scored list of all of the Availability Zones.

Challenges

Given the configuration you used above, try to answer the following questions. Click to expand and see the answers.

1. What are the Spot placement scores for the specific requirements in the different regions?
2. How can I filter the regions in the Spot placement score request?
3. How can I see Spot placement scores by individual Availability Zones?
4. How can I specify instance types in the Spot placement score request?

Optional reads

You can learn more about spot placement score by reading the launch blog post.

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