Overview of AWS Auto Scaling

AWS Auto Scaling is a service that monitors your applications and automatically adjusts capacity according to your specified configurations, and thus help avoid performance bottlenecks while optimizing the cost.

The AWS Auto Scaling service may be used on following services:

  • EC2 Instances
  • EC2 Spot Fleets
  • ECS Tasks
  • DynamoDB Throughput Capacity – Read and Write Capacity Units for Tables and Indexes
  • Aurora Replicas


AWS Auto Scaling vs Amazon EC2 Auto Scaling (Group)

EC2 has had for long a similar service called “Amazon EC2 Auto Scaling (Group)”, which by itself is a great service. AWS Auto Scaling service is more dynamic and can be applied on multiple services.

  • You can still use individual service’s auto-scaling for some granular or resource / service specific conditions.
  • You can use both of these services in tandem as well.
  • EC2 Auto Scaling works one Auto Scaling Group at a time, whereas AWS Auto Scaling can be applied application-wide (and along with other resources besides EC2)


Predictive Scaling

Predictive Scaling predicts future traffic and accordingly provisions the number of EC2 instances.

  • Currently only for EC2, with plans to roll-out for other services
  • This service leverages Machine Learning to analyze patterns. A good prediction needs up to two weeks of historical data, but starts generating predictive scaling with as little as a day’s worth of data.
  • It works best for sites that have periodic fluctuations in traffic. It does not work well for totally random spikes.
  • Once the initial set of predictions have been made and the scaling plans are in place, the plans are updated daily and forecasts are made for the following 2 days.
    • That is – every 24 hours, Predictive Scaling forecasts 48 hours into the future, and schedules capacity changes for those 48 hours.
  • Predictive scaling maintains the minimum capacity based on historical demand; this ensures that any gaps in the metrics won’t cause an inadvertent scale-in.



There is no extra charge for Auto Scaling. You pay for the underlying resources based on their respective costs.