Create EC2 Spot Auto Scaling Group and Capacity Provider

Create the Spot Auto Scaling Group

In this section, you create an Auto Scaling group for EC2 Spot Instances using the Launch Template created by the CloudFormation stack. This procedure is exactly the same as the previous section, except for a few changes specific to the configuration for Spot Instances.

Copy the file templates/asg.json for the EC2 Auto Scaling group configuration.

cd ~/environment/ec2-spot-workshops/workshops/ecs-spot-capacity-providers/
cp templates/asg.json spot-asg.json

Read the spot-asg.json file. We configured the instance diversification in spot-asg.json according to the guidelines from our previous section. Notice how we’ve chosen instance types with similar hardware characteristics in order to have a consistent auto scaling experience. Check also how the allocation strategy chosen for Spot is Capacity-optimized, this will let the ASG select the instances that mimimize the frequency of spot interruptions.

We will now replace the environment variables in the spot-asg.json file with the Spot settings, setting the OnDemand percentage to 0 and substituting the CloudFormation environment variables that we exported earlier.

export ASG_NAME=EcsSpotWorkshop-ASG-SPOT
export OD_PERCENTAGE=0 # Note that ASG will have 0% On-Demand, 100% Spot
sed -i -e "s#%ASG_NAME%#$ASG_NAME#g"  -e "s#%OD_PERCENTAGE%#$OD_PERCENTAGE#g" -e "s#%PUBLIC_SUBNET_LIST%#$VPCPublicSubnets#g" -e "s#%LAUNCH_TEMPLATE_ID%#$LaunchTemplateId#g" spot-asg.json

Finally we create the ASG for the Spot Instances and store the ARN for the spot group.

aws autoscaling create-auto-scaling-group --cli-input-json  file://spot-asg.json
ASG_ARN=$(aws autoscaling  describe-auto-scaling-groups --auto-scaling-group-name $ASG_NAME | jq -r '.AutoScalingGroups[0].AutoScalingGroupARN')

The output of the above command will appear as below:

EcsSpotWorkshop-ASG-SPOT ARN=arn:aws:autoscaling:us-east-1:0004746XXXX:autoScalingGroup:dd7a67e0-4df0-4cda-98d7-7e13c36dec5b:autoScalingGroupName/EcsSpotWorkshop-ASG-SPOT

The EC2 Spot auto scaling group should appear as below in the console Note that there is no capacity provisioned i.e. desired capacity is zero in the ASG. We expect the capacity to scale up automatically when we deploy applications later.

Create the Spot Capacity Provider

To create the capacity provider, follow these steps:

  • Open the ECS console in the region where you are looking to launch your cluster.
  • Click Clusters
  • Click EcsSpotWorkshop
  • Click the tab Capacity Providers
  • Click Create
  • For Capacity provider name, enter CP-SPOT
  • For Auto Scaling group, select EcsSpotWorkshop-ASG-SPOT
  • For Managed Scaling, leave with default selection of Enabled
  • For Target capacity %, enter 100
  • For Managed termination protection, leave with default selection of Enabled
  • Click on Create on the bottom right

Capacity Provider on Spot ASG

We encourage you to do a similar exercise to what you did with the OnDemand Auto Scaling Group. Check in the console that the ECS Cluster has the new CP-SPOT Capacity Provider, and check out the configuration and scaling policy created on the EcsSpotWorkshop-ASG-SPOT Auto Scaling Group

Refresh the Capacity Providers tab, and you will see the CP-SPOT is created and attached to the ECS cluster.

Capacity Provider on Spot ASG