Question
A company is running an application on Amazon EC2 instances in an Auto Scaling group. The application stores logs locally. A security engineer noticed that logs were lost after a scale-in event. The security engineer needs to recommend a solution to ensure the durability and availability of log data. All logs must be kept for a minimum of 1 year for auditing purposes.
What should the security engineer recommend?
- A. Within the Auto Scaling lifecycle, add a hook to create and attach an Amazon Elastic Block Store (Amazon EBS) log volume each time an EC2 instance is created. When the instance is terminated, the EBS volume can be reattached to another instance for log review.
- B. Create an Amazon Elastic File System (Amazon EFS) file system and add a command in the user data section of the Auto Scaling launch template to mount the EFS file system during EC2 instance creation. Configure a process on the instance to copy the logs once a day from an instance Amazon Elastic Block Store (Amazon EBS) volume to a directory in the EFS file system.
- C. Add an Amazon CloudWatch agent into the AMI used in the Auto Scaling group. Configure the CloudWatch agent to send the logs to Amazon CloudWatch Logs for review. Correct
- D. Within the Auto Scaling lifecycle, add a lifecycle hook at the terminating state transition and alert the engineering team by using a lifecycle notification to Amazon Simple Notification Service (Amazon SNS). Configure the hook to remain in the Terminating:Wait state for 1 hour to allow manual review of the security logs prior to instance termination.
Explanation
Option C is correct because the CloudWatch agent sends the application logs off the instance to Amazon CloudWatch Logs as they are written, so the logs survive when Auto Scaling terminates an instance during scale-in. CloudWatch Logs stores the data durably, and a retention policy on the log group (for example 365 days or more, up to 10 years, or never expire) keeps the logs for the 1-year audit requirement. Option A relies on volumes that must be found and reattached manually. Option B copies logs only once a day, so up to a day of logs is lost when an instance is terminated. Option D only delays termination for manual review and does not keep the logs.
