AWS Certified DevOps Engineer – Professional — Question 117

A company wants to use a grid system for proprietary enterprise in-memory data store on top of AWS. The system can run in multiple server nodes in any Linux-based distribution. The system must be able to reconfigure the entire cluster every time a node is added or removed. When adding or removing nodes, an /etc/cluster/nodes.config file must be updated listing the IP addresses of the current node member of that cluster.

The company wants to automate the task of adding new nodes to a cluster.

What can a DevOps engineer do to meet these requirements?

Answer options

• A. Use AWS OpsWorks Stacks to layer the server nodes of that cluster. Create a Chief recipe that populates the content of the /etc/cluster/nodes.config file and restarts the service by using the current members of the layers. Assign that recipe to the Configure lifecycle event.
• B. Put the file nodes.config in version control. Create an AWS CodeDeploy deployment configuration and deployment group based on an Amazon EC2 tag value for the cluster nodes. When adding a new node to the cluster, update the file with all tagged instances, and make a commit in version control. Deploy the new file and restart the services.
• C. Create an Amazon S3 bucket and upload a version of the /etc/cluster/nodes.config file. Create a crontab script that will poll for that S3 file and download it frequently. Use a process manager, such as Monit or systemd, to restart the cluster services when it detects that the new file was modified. When adding a node to the cluster, edit the file’s most recent members. Upload the new file to the S3 bucket.
• D. Create a user data script that lists all members of the current security group of the cluster and automatically updates the /etc/cluster/nodes.config file whenever a new instance is added to the cluster.

Correct answer: A

Explanation

Option A is correct because using AWS OpsWorks Stacks allows for effective management of the server nodes, and the Chef recipe can automate the update of the /etc/cluster/nodes.config file and service restart. Options B, C, and D do not fully automate the cluster reconfiguration process as required; they involve manual steps or additional external systems that complicate the task.