AWS CloudWatch 启动/停止 EC2 实例

Question

Just looking the way to start/stop a AWS EC2 instance in case of CPU utilization increase or decrease on another EC2 instacne. I know there is service available Auto Scaling in AWS but I have a scenario where I can't take advantage of this service.

So just looking if it is possible or anyone can help me on this.

Just detailing the concern like suppose I have 2 EC2 instance on AWS account by name EC21 and EC22. By default, EC22 instance is stopped.

Now I need to setup CloudWatch or any other service to check if load/CPU utilization increase on EC21 instance by 70% then need to start EC22 server and similarly if load decrease on EC21 instance by 30% then stop EC22 server.

Please advice!

Answer 1

When your CloudWatch alarm is triggered, it will notify an SNS topic. You can have that SNS topic then invoke a Lambda function, which can then start your EC2 instance.

1. Create an AWS Lambda function that starts your EC2 instance.
2. Configure your SNS topic to invoke your Lambda function when it receives messages. You can read about that here: Invoking Lambda functions using Amazon SNS notifications
3. Finally, ensure your CloudWatch alert sends messages to the SNS topic.

Answer 2

Yes this is possible for certain types of EC2 instances. Check this detailed guide using which you can set up the triggers in your EC2 instances based on AWS Cloud Watch metrics.

http://docs.aws.amazon.com/AmazonCloudWatch/latest/DeveloperGuide/UsingAlarmActions.html

Answer 3

I think your problem might fit the scenario which I'm also trying to solve now - I have some functionality which cannot be solved with Lambdas because of their low lifetime, so I need a relatively short-lived EC2 instance to accomplish the task.

The solution is similar to the one described by Matt, but without SNS, using AWS triggers to launch a lambda function to start the instance. Added benefit is that the lambda function can itself verify whether the EC2 start is really needed.

How do I stop and start Amazon EC2 instances at regular intervals using AWS Lambda?

Issue

I want to reduce my Amazon Elastic Cloud Compute (Amazon EC2) usage by stopping and starting instances at predefined times or utilization thresholds. Can I configure AWS Lambda and Amazon CloudWatch to help me do that automatically?

Short Description

You can use a CloudWatch Event to trigger a Lambda function to start and stop your EC2 instances at scheduled intervals.

Source: AWS Knowledge Center