AWS Certified DevOps Engineer – Professional (DOP-C02) — Question 107

A company wants to use a grid system for a proprietary enterprise in-memory data store on top of AWS. This 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 members 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 Chef recipe that populates the content of the /etc/cluster/nodes.config file and restarts the service by using the current members of the layer. 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 it effectively uses AWS OpsWorks Stacks and a Chef recipe to automate the configuration of the cluster, ensuring that the /etc/cluster/nodes.config file is updated and services are restarted based on the current nodes. Option B relies on manual updates and version control, which is less efficient for automation. Option C introduces unnecessary complexity with S3 and polling, while Option D does not utilize the capabilities of AWS services like OpsWorks, making it less optimal for the requirement.