ECR Repository should use customer managed keys to allow more control

Explanation

Images in the ECR repository are encrypted by default using AWS managed encryption keys. To increase control of the encryption and control the management of factors like key rotation, use a Customer Managed Key.

Possible Impact

Using AWS managed keys does not allow for fine grained control

Suggested Resolution

Use customer managed keys

Insecure Example

The following example will fail the aws-ecr-repository-customer-key check.

resource "aws_ecr_repository" "bad_example" {
	name                 = "bar"
	image_tag_mutability = "MUTABLE"
  
	image_scanning_configuration {
	  scan_on_push = true
	}
  }

Secure Example

The following example will pass the aws-ecr-repository-customer-key check.

resource "aws_kms_key" "ecr_kms" {
	enable_key_rotation = true
}

resource "aws_ecr_repository" "good_example" {
	name                 = "bar"
	image_tag_mutability = "MUTABLE"
  
	image_scanning_configuration {
	  scan_on_push = true
	}

	encryption_configuration {
		encryption_type = "KMS"
		kms_key = aws_kms_key.ecr_kms.key_id
	}
  }

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