Question

a reporting application runs on amazon ec2 instances behind an application load balancer. the instances run in an amazon ec2 auto scaling group across multiple availability zones. for complex reports, the application can take up to 15 minutes to respond to a request. a solutions architect is concerned that users will receive http 5xx errors if a report request is in process during a scale-in event. what should the solutions architect do to ensure that user requests will be completed before instances are terminated?

Answer 1

To prevent HTTP 5xx errors during scale-in events, implement connection draining on the ALB and set up lifecycle hooks in the EC2 Auto Scaling group to ensure user requests are completed before instance termination.

Step-by-step explanation:

To mitigate the issue of HTTP 5xx errors during scale-in events of an Amazon EC2 Auto Scaling group, the solutions architect can implement a feature called connection draining on the Application Load Balancer (ALB). This ensures that ongoing requests are completed before an instance is terminated.

Connection draining, also known as deregistration delay, will keep the instance in a deregistering state until in-flight requests have finished processing up to a configured timeout, which should be longer than the longest expected processing time for reports.

Additionally, the solutions architect may consider setting up lifecycle hooks for the Auto Scaling group. This allows you to pause the termination of an instance after it has been selected for scale-in, giving you the opportunity to perform custom actions.

For example, you could use lifecycle hooks to ensure that report generation is complete or to move the session to another server. It is important to adjust these settings according to the application's specific needs to avoid premature terminations and ensure a seamless user experience.