Create an EC2 Auto Scaling Group

Amazon EC2 Auto Scaling helps you maintain application availability and allows you to dynamically scale your Amazon EC2 capacity up or down automatically according to conditions you define. You can use Amazon EC2 Auto Scaling for fleet management of EC2 instances to help maintain the health and availability of your fleet and ensure that you are running your desired number of Amazon EC2 instances. You can also use Amazon EC2 Auto Scaling for dynamic scaling of EC2 instances in order to automatically increase the number of Amazon EC2 instances during demand spikes to maintain performance and decrease capacity during lulls to reduce costs. Amazon EC2 Auto Scaling is well suited both to applications that have stable demand patterns or that experience hourly, daily, or weekly variability in usage.

  1. Open asg.json on the Cloud9 editor and review the configuration. Pay special attention at the Overrides and the InstancesDistribution configuration blocks and try to guess how many instances of which instance type and which purchase option will be launched. Take a look at our docs to review how InstancesDistribution and allocation strategies work.

    Help me understand the AutoScaling configuration

  2. You will notice there are placeholder values for %TargetGroupArn%, %publicSubnet1% and %publicSubnet2%. To update the configuration file with the values of the Target Group you created previously and the outputs from the CloudFormation template, execute the following command:

    sed -i.bak -e "s#%TargetGroupARN%#$TargetGroupArn#g" -e "s#%publicSubnet1%#$publicSubnet1#g" -e "s#%publicSubnet2%#$publicSubnet2#g" asg.json
  3. Save the file and create the auto scaling group:

    aws autoscaling create-auto-scaling-group --cli-input-json file://asg.json

    This command will not return any output if it is successful.

  4. Browse to the Auto Scaling console and check out your newly created auto scaling group. Take a look at the instances it has deployed.

Optional exercise

Now that you have deployed an EC2 AutoScaling group with Mixed Instance Types and Purchase Options, take some time to manually scale out and scale in the number of instances of the group and see which instance types AutoScaling launches. Also, modify the SpotInstancePools parameter and experiment with the capacity-optimized allocation strategy to get a good grasp of how the different allocation strategies behave.