The type of principal CodeBuild will use to pull your build Docker image.
CODEBUILD specifies that CodeBuild uses its own identity when pulling the image.
This means the resource policy of the ECR repository that hosts the image will be modified to trust CodeBuild’s service principal. This is the required principal type when using CodeBuild’s pre-defined images.
SERVICE_ROLE specifies that AWS CodeBuild uses the project’s role when pulling the image.
The role will be granted pull permissions on the ECR repository hosting the image.