Which solution will meet this requirement MOST cost-effectively?
Mount an Amazon Elastic Block Store (Amazon EBS) volume onto one of the EC2 instances. Deploy a file system on the EBS volume. Use the host operating system to share a folder. Update the application code to read and write configuration files from the shared folder.
Deploy a micro EC2 instance with an instance store volume. Use the host operating system to share a folder. Update the application code to read and write configuration files from the shared folder.
Create an Amazon S3 bucket to host the repository. Migrate the existing .xml files to the S3 bucket. Update the application code to use the AWS SDK to read and write configuration files from Amazon S3.
Create an Amazon S3 bucket to host the repository. Migrate the existing xml files to the S3 bucket. Mount the S3 bucket to the EC2 instances as a local volume. Update the application code to read and write configuration files from the disk.
Explanations:
Using an Amazon EBS volume on a single EC2 instance does not provide high availability, as it creates a single point of failure. If that instance goes down, the shared configuration repository will become unavailable. Additionally, EBS volumes cannot be mounted simultaneously across multiple EC2 instances, which limits accessibility.
Deploying a micro EC2 instance with an instance store volume does not provide high availability or redundancy. Instance store volumes are ephemeral and data would be lost if the instance fails. Like option A, this approach also results in a single point of failure without a shared configuration solution.
Creating an Amazon S3 bucket provides a highly available and durable storage solution. By migrating the .xml files to S3 and updating the application code to use the AWS SDK, the application can access configuration files from any EC2 instance, achieving high availability and cost-effectiveness since S3 is pay-as-you-go.
While mounting an S3 bucket to EC2 instances can be done, it introduces complexity and may not perform as well as directly using the AWS SDK to access S3. This method also risks issues related to the consistency model of S3, particularly if the application expects a file system-like behavior. Moreover, it complicates the architecture without adding significant benefits over option C.
I opine that the answer is:
Create an Amazon S3 bucket to host the repository. Migrate the existing .xml files to the S3 bucket. Update the application code to use the AWS SDK to read and write configuration files from Amazon S3.