Your organization owns several AWS accounts. The AWS operation team creates several base docker images in AWS ECR. Another development team is working on a new project in which the build phase needs to use AWS CodeBuild to build artifacts. One requirement is that the environment image of CodeBuild must use an ECR docker image owned by the operation team. However, the ECR docker image is located in different AWS account. How would you resolve this and create the CodeBuild project?

Answer options:

A.Select AWS managed Ubuntu image. In the image, pull the ECR docker image from another account. 
B.CodeBuild does not support cross account ECR image. Copy the image to the ECR registry in the same account first.
C.Select custom image and choose ECR image registry. Enter the full ECR repository URI for the repository in the other account.
D.Select custom image and choose Other registry for an external Docker registry. In external registry URI, enter the ECR repository URI of the other account.

Correct Answer – C
AWS CodeBuild supports accessing cross-account ECR images according to
https://aws.amazon.com/about-aws/whats-new/2019/01/aws-codebuild-now-supports-accessing-cross-account-ecr-images/.
Option A is incorrect: Because AWS managed image should not be used. For ECR images, custom image should be configured.
Option B is incorrect: Because cross-account ECR image is supported.
Option C is CORRECT: Refer to the below example:
Option D is incorrect: Because external Docker registry is not used for AWS ECR. Other registries such as public DockerHub would use external Docker registry.