Preventing EC2 Instances Termination During Video Processing | Solution for Autoscaling Group
Question
You have a set of EC2 Instances in an Autoscaling Group that processes messages from an SQS queue.
The messages contain the location in S3 from where video's need to be processed by the EC2 Instances.
When a scale in happens, it is noticed that an at times that the EC2 Instance is still in a state of processing a video when the instance is terminated.
How can you implement a solution which will ensure this does not happen?
Answers
Explanations
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A. B. C. D.Answer - C.
This is a case where lifecycle policies can be used.
The lifecycle policy can be used to put the instance in a state of Terminating:Wait , complete the processing and then send a signal to complete the termination.
Auto Scaling lifecycle hooks enable you to perform custom actions by pausing instances as Auto Scaling launches or terminates them.
For example, while your newly launched instance is paused, you could install or configure software on it.
For more information on Autoscaling lifecycle hooks , please visit the below URL:
http://docs.aws.amazon.com/autoscaling/latest/userguide/lifecycle-hooks.htmlWhen an Auto Scaling Group scales in, it terminates EC2 instances that are no longer needed. In this scenario, if an EC2 instance is still processing a video when the termination occurs, it can result in loss of data or incomplete processing of videos. To prevent this from happening, you can implement the following solution:
Option C: Use lifecycle hooks to ensure the processing is complete before the termination occurs.
Lifecycle hooks are used to perform custom actions as instances launch or terminate within an Auto Scaling Group. By using a lifecycle hook, you can delay the termination of an EC2 instance until a specified action is taken.
To implement this solution, you would need to create a lifecycle hook that would wait for the EC2 instance to complete processing the video before it is terminated. Here are the steps to implement this solution:
Create a lifecycle hook: Create a new lifecycle hook for the Auto Scaling Group that processes messages from the SQS queue. This hook should be triggered when an instance is about to be terminated.
Define the action for the lifecycle hook: Define the action to be taken when the lifecycle hook is triggered. In this case, the action should wait for the EC2 instance to complete processing the video before the instance is terminated.
Update the Auto Scaling Group: Update the Auto Scaling Group to use the newly created lifecycle hook. This can be done by updating the Launch Configuration or Launch Template used by the Auto Scaling Group.
Test the solution: Test the solution to ensure that the EC2 instance is not terminated until the video processing is complete.
By implementing this solution, you can ensure that EC2 instances are not terminated while still processing videos, thereby preventing data loss and incomplete processing. Option C is the correct answer.
Option A: Changing the CoolDown property for the Autoscaling Group is not a solution to prevent the termination of an EC2 instance while it is still processing a video.
Option B: Suspending the AZRebalance termination policy is not a solution to prevent the termination of an EC2 instance while it is still processing a video.
Option D: Increasing the minimum and maximum size for the Auto Scaling group and changing the scaling policies so they scale less dynamically is not a solution to prevent the termination of an EC2 instance while it is still processing a video.
