How to do user specific deployment of web application?

I have a web application and I came across a scenario where I am about to release a new version of my application but I want that version to be available to only a specific set of users first?

For example my app has users (a, b, c, d, e, f g, h). I am releasing v2 of my app, these users do not need to know that I have released a new version of my app. Whenever users (a,b,c) try to access the application they should be redirected to v2 and whenever rest of the users try to access the application they should be redirected to v1.

How can this be achieved from the point of view of deployment and system design?