Importing an existing Auto Scaling Group is a quick and easy process.
1. Navigate to Auto Scaling Group - Overview. The Auto scaling group that is not yet imported will have a menu item called 'Import'
Click on 'Import' . The Import Auto Scaling Group dialog opens up
The Auto scaling Group Name and Region are pre populated based on the existing Auto Scaling group Name. Provide the appropriate Application Context
Application Context
Application Context provides indication about the criticality of the cluster and whether it should be optimized for availability for Cost / Availability. Currently it supports the following options
Minimum Price : Choose this option for non critical or short duration clusters. This indicates that the cluster can be prioritized for using the lowest price among the selected instance type(s) and there is no minimum number of instances provisioned using On-Demand Instances. The instance life cycle management applies to this so as to monitor and replace instances if there are any interruptions. e.g. Dev or Test clusters that do not have critical data written at a frequency of greater than once every few seconds. ASG for Staging to verify or reproduce issues with production settings for a short duration and spin it down once the work is completed.
Optimum Price - Uptime : Choose this option for applications that need optimal mix of cost and uptime. This is the default option. This provisions a minumum number of instances in OnDemand at all times and the rest as spot/ondemand based on availability. The algorithm prefers higher available instance type(s) over price until a certain percentage. The instance life cycle management applies to this so as it monitor and replace instances if there are any interruptions. e.g. Long running Dev/Test/Staging Clusters for all types of workloads. Choosing this for Production clusters is suitable for stateless workloads. It is not suitable for production clusters if the stateless requests typically take 120 seconds or more.
Maximum Availability : Choose this option if you want to prioritize availability and reduce frequency of interruptions even if cost savings are less than optimal. This provisions a higher number of ondemand instances( ** but not all instances are OnDemand Instances**) and prefers instance types with higher availability even if they are more expensive. This is suitable for all production workloads that are stateless / content driven. Not suitable for workloads which have high frequency disk persisted storage or workloads that take stateless actions that go beyond 120 seconds.
Terminate Detached Instances : Based on the Application Context and which type of instances are provisioned , some of the instances will move Spot Instances. This settings gives a choice of leaving the existing instances that were part of the ASG detached from ASG but still running or to be terminated once the successful migration is complete.
Click on Import. Once the Import is successful, the page will navigate back to Overview page. Please note that based on various parameters, the import can take upto a few minutes to complete.