Monday, August 3, 2015

AWS autoscaling groups for a fixed number of instances

AWS autoscaling groups are a way to scale capacity up and down when it is needed. However, autoscaling groups are a great way to just keep a fixed number of instances alive. Let's say we have an app that we always want two instances of running. If one of them dies, it would nice to automatically restart it. To do this, simply create an autoscaling group with a fixed size:
"myautoscalinggroup" : {
   "Type" : "AWS::AutoScaling::AutoScalingGroup",
   "Properties" : {
      "DesiredCapacity" : 2,
      "MinSize" : 2,
      "MaxSize" : 2,
Now Amazon does the heavy lifting for us, and we'll always have a pool of two instances.