Amazon EC2 Auto Scaling
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.
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Improve Fault Tolerance
Amazon EC2 Auto Scaling can detect when an instance is unhealthy, terminate it, and replace it with a new one.
Increase Application Availability
Amazon EC2 Auto Scaling ensures that your application always has the right amount of compute capacity.
Amazon EC2 Auto Scaling adds new instances only when necessary, and terminates them when no longer needed.
How it works
Whether you are running one Amazon EC2 instance or thousands, you can use Amazon EC2 Auto Scaling to detect impaired Amazon EC2 instances and unhealthy applications, and replace the instances without your intervention. This ensures that your application is getting the compute capacity that you expect. Amazon EC2 Auto Scaling will perform three main functions to automate fleet management for EC2 instances:
- Monitor the health of running instances
Amazon EC2 Auto Scaling ensures that your application is able to receive traffic and that EC2 instances are working properly. Amazon EC2 Auto Scaling periodically performs health checks to identify any instances that are unhealthy.
- Replace impaired instances automatically
When an impaired instance fails a health check, Amazon EC2 Auto Scaling automatically terminates it and replaces it with a new one. That means that you don’t need to respond manually when an instance needs replacing.
- Balance capacity across Availability Zones
Amazon EC2 Auto Scaling can automatically balance instances across zones, and always launches new instances so that they are balanced between zones as evenly as possible across your entire fleet.
Amazon EC2 Auto Scaling enables you to follow the demand curve for your applications closely, reducing the need to manually provision Amazon EC2 capacity in advance. For example, you can use target tracking scaling policies to select a load metric for your application, such as CPU utilization. Or, you could set a target value using the new “Request Count Per Target” metric from Application Load Balancer, a load balancing option for the Elastic Load Balancing service. Amazon EC2 Auto Scaling will then automatically adjust the number of EC2 instances as needed to maintain your target.
You can also use simple scaling policies to set a condition to add new Amazon EC2 instances in increments when the average utilization of your Amazon EC2 fleet is high, and similarly, you can set a condition to remove instances in the same increments when CPU utilization is low. If you have predictable load changes, you can also set a schedule through Amazon EC2 Auto Scaling to plan your scaling activities.
Amazon EC2 Auto Scaling can also be used with Amazon CloudWatch, which can send alarms to trigger scaling activities, and Elastic Load Balancing to help distribute traffic to your instances within EC2 Auto Scaling groups.
You can also use Amazon EC2 Auto Scaling in combination with AWS Auto Scaling to scale multiple services.