AWS VPC Private link to SNS service - amazon-sns

Question

I am testing out publishing to SNS using the AWS Privatelink feature. While at that, I found that I am able to create multiple endpoints to the SNS service (com.amazonaws.us-west-1.sns). Is there a valid use case for having multiple endpoints to the SNS service ?

Answer 1

An endpoint is a VPC level construct and therefore not usable outside the VPC it was created in. I am assuming in your question you are looking for use cases for having multiple endpoints to the same AWS service in the same VPC.
Creation of an endpoint requires several input parameters, several of which are listed under Creating an Interface Endpoint at Interface VPC Endpoints (AWS PrivateLink). Alternatively, these input parameters can be best experienced on the endpoint creation form in the AWS Console itself.
It is to allow for varying combinations of these input parameters, to build or accommodate fine-grained security policies and segmentation practices, that multiple endpoints make sense.
For instance, you may have two different applications in the same VPC, best given access to the SNS service with actions and topics specific to their unique requirements. This example policy from the documentation at Creating an Amazon VPC Endpoint Policy for Amazon SNS should be able to highlight the possibilities:
{
"Statement": [{
"Action": ["sns:Publish"],
"Effect": "Allow",
"Resource": "arn:aws:sns:us-east-2:123456789012:MyTopic",
"Principal": "arn:aws:iam:123456789012us-east:user/MyUser"
}]
}
Alternatively, your applications may require association with different Security Groups (which is one of the input parameters to creating an endpoint.) In which case, dedicated endpoints to those segments of the network, optionally with other customisations such as that of the associated policy, would provide the desired levels of segmentation. The segmentation itself may be required to actively prevent accidental application misconfiguration from negatively impacting the business, or to contain threats if they were to arise in a particular application.