The automatic expansion of aws ec2 is mainly divided into scale out and scale in, one expands and the other shrinks, so it is called elastic.
Steps to configure auto scale through aws console:
1" Create a scale configuration, which is equivalent to creating a template for ec2 instance
2" Create an auto scale group, select scale configuration, configure the number of min instances, the number of desired instances, and the number of max instances
3" Create a scale policy, such as increasing instance, decreasing instance, adjusting parameters related to the number of instances, etc.
4" Configure the alarm through aws cloud watch, select the metrics related to auto scale for threshold monitoring, and once the conditions match, trigger the corresponding scale policy to scale in or scale out