Runner helper images versions

Posting here from Slack to keep track

I have two questions about the runner helper docker images. I created an AWS AMI with a few docker images images that I know will always be used by the runners so that I can speed up the jobs, one of which is x86_64-latest-servercore1809 for the runner helper.

Though, when looking at the jobs, I noticed that it was always pulling a different image: x86_64-102c81ba-servercore1809. Looking at a couple more jobs I also saw it using the x86_64-f9e6aed5-servercore1809 image 🤔

Here's my questions:

• What defines the runner helper image that is going to be used?
• Why latest is not the latest version? 🤔