Auto scale behavior of AWS ECS service - amazon-web-services

Question

I am trying to test auto scale behavior in amazon ECS. Here is how i tested
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;
public class LoadHttp {
private static final String GET_URL = "http://tournament-ecs-weather-lb-1526102172.ap-south-1.elb.amazonaws.com/status";
public static void main(String[] args) throws IOException {
System.out.println("GET DONE");
while(true){
sendGET();
}
}
private static void sendGET() throws IOException {
Thread t = new Thread(() -> {
URL obj;
try {
obj = new URL(GET_URL);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
con.setRequestMethod("GET");
con.setConnectTimeout(5000);
int responseCode = con.getResponseCode();
System.out.println(responseCode);
} catch (Exception e) {
e.printStackTrace();
}
});
t.start();
}
}
and configuration of auto scale of service that i am running
here is my auto scale group configuration
I am using ECS Service to create cluster and my service is running in docker container. Still after executing my test code i found my service is not getting autoscaled. Number of container instance is still one. If you need additional information I will be happy.

Answer 1

If I understood your question, the service is autoscaled when there are not enough resources available in the current instance to handle the requests.
In your particular case, you have set the Min value of the instances as 0 which tells that the system should react fine even there is no instance running. You need to have at least 1 for the min value to make the whole cluster run ok. I believe that for this reason your autoscaling is not launching any instance.
Also, I would suggest you to add the Elastic Load balancer to your autoscaling group which launch asks autoscaling group to launch more instances when the minimum number of instances specified in your autoscaling are not healthy.
Lastly, to test if the autoscaling group is working or not, you check the availability zone of your instance and note that down. Now terminate your instance. Since the running instance is terminated the autoscaling group should automatically launch an instance in different availability zone. If it launches new instance in different availability zone than the terminated instance then it works ok.
Hope this will help.