Create On-Demand Auto Scaling Group and Capacity Provider

Create the OnDemand Auto Scaling Group

So far we have an ECS Cluster created and a Launch Template that bootstrap ECS agents and links them against the ECS Cluster. In this section, we will create an EC2 Auto Scaling group (ASG) for On-Demand Instances using the Launch Template created by the CloudFormation stack. Go back to your Cloud9 environment and 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 .

We will now replace the environment variables in the asg.json file with the On-Demand settings, changing the OnDemand percentage field in ASG and substituting the CloudFormation environment variables that we exported earlier with the asg.json placeholder names in the template.

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

Read the asg.json file and understand the various configuration options for the EC2 Auto Scaling group. Check how although this is an OnDemand we still apply instance diversification with the Prioritized allocation strategy. Check how the Launch Template we reviewed in the previous section is referenced in the Auto Scaling Group.

Create the ASG for the On-Demand Instances.

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

The output of the above command will appear and will be similar to the one below. We have captured the ASG ARM to use in the next sections.

EcsSpotWorkshop-ASG-OD ARN=arn:aws:autoscaling:us-east-1:0004746XXXX:autoScalingGroup:1e9de503-068e-4d78-8272-82536fc92d14:autoScalingGroupName/EcsSpotWorkshop-ASG-OD

The On-Demand auto scaling group will appear as below in the console

Optional Exercises

Based on the configuration and steps above, try to answer the following questions:

  • Now that we have created an OnDemand AutoScaling Group, Can you guess how much capacity we have allocated to our Cluster ?
Show me the answer
  • How did we configured the Auto Scaling Group to Scale on demand instances?
Show me the answer

Create the OnDemand Capacity Provider

To create a capacity provider, follow these steps:

  • Open the ECS console in the region where you deployed the CFN template.
  • Click Clusters
  • Click EcsSpotWorkshop
  • Click the tab Capacity Providers
  • Click Create
  • For capacity provider name, enter CP-OD
  • For Auto Scaling group, select EcsSpotWorkshop-ASG-OD
  • 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 OD ASG

Optional Exercises

Based on the configuration and steps above, try to answer the following questions:

  • How would you check in the console the details about the new capacity provider created?
Show me the answer
  • When creating the capacity provider against the Auto Scaling Group, we did enable “Managed Scaling” or CAS (Cluster Auto Scaling). How can I confirm the right scaling policy has been created for this Auto Scaling Group?
Show me the answer

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