AWS Certified Solutions Architect – Professional — Question 951

A company is migrating its on-premises build artifact server to an AWS solution. The current system consists of an Apache HTTP server that serves artifacts to clients on the local network, restricted by the perimeter firewall. The artifact consumers are largely build automation scripts that download artifacts via anonymous
HTTP, which the company will be unable to modify within its migration timetable.
The company decides to move the solution to Amazon S3 static website hosting. The artifact consumers will be migrated to Amazon EC2 instances located within both public and private subnets in a virtual private cloud (VPC).
Which solution will permit the artifact consumers to download artifacts without modifying the existing automation scripts?

Answer options

• A. Create a NAT gateway within a public subnet of the VPC. Add a default route pointing to the NAT gateway into the route table associated with the subnets containing consumers. Configure the bucket policy to allow the s3:ListBucket and s3:GetObject actions using the condition IpAddress and the condition key aws:SourceIp matching the elastic IP address of the NAT gateway.
• B. Create a VPC endpoint and add it to the route table associated with subnets containing consumers. Configure the bucket policy to allow s3:ListBucket and s3:GetObject actions using the condition StringEquals and the condition key aws:sourceVpce matching the identification of the VPC endpoint.
• C. Create an IAM role and instance profile for Amazon EC2 and attach it to the instances that consume build artifacts. Configure the bucket policy to allow the s3:ListBucket and s3:GetObjects actions for the principal matching the IAM role created.
• D. Create a VPC endpoint and add it to the route table associated with subnets containing consumers. Configure the bucket policy to allow s3:ListBucket and s3:GetObject actions using the condition IpAddress and the condition key aws:SourceIp matching the VPC CIDR block.

Correct answer: B

Explanation

Since the legacy build scripts perform anonymous HTTP requests and cannot be modified, IAM authentication using instance profiles (Option C) is not feasible. Using a VPC gateway endpoint allows the S3 bucket policy to permit anonymous access securely by restricting requests to only those originating from the specific VPC endpoint ID using the aws:sourceVpce condition. Option D is incorrect because S3 gateway endpoints do not preserve the private VPC CIDR IPs in a way that allows aws:SourceIp filtering, and Option A does not cover instances in public subnets which bypass the NAT gateway.