Amazon EC2 Auto Scaling

Amazon EC2 Auto Scaling:

Amazon EC2 Auto Scaling helps you ensure thatyou have the correct number of Amazon EC2 instances available to handle theload for your application. You create collections of EC2 instances, called AutoScaling groups. You can specify the minimum number of instances ineach Auto Scaling group, and Amazon EC2 Auto Scaling ensures that your groupnever goes below this size. You can identify the most number of instances ineach Auto Scaling group, and Amazon EC2 Auto Scaling ensures that your groupnever goes above this size. If you specify the preferred capacity, either whenyou create the group or at any time thereafter, Amazon EC2 Auto Scaling ensuresthat your group has this many instances. If you specify scaling policies, thenAmazon EC2 Auto Scaling can launch or finish instances as demand on yourapplication increases or decreases.

Forexample, the following Auto Scaling group has a minimum size of one instance, adesired capacity of two instances, and a maximum size of four instances. Thescaling policies that you define adjust the number of instances, within yourminimum and maximum number of instances, based on the criteria that youspecify.

Auto Scaling Components:

Groups:

Your EC2 instancesare ready in to groups, so that they can be treated as a rational unit for thepurposes of scaling and running. When you create a group, you can specify itsminimum and, desired  number of EC2instances.

Configuration templates:

Your groupuses a launch template or a launch configuration as a patter templates for itsEC2 instances. You can identify information such as the AMI ID, instance type, keypair, security groups, and block device mapping for your instances.

Scaling options:

.AmazonEC2 Auto Scaling provides several way for you to scale your Scaling groups.Forexample, you can configure a group to scale based on the incidence of specific conditions(dynamicscaling) or on a schedule.