Gitlab shared runner documentation unclear


I’m planning on using Gitlab’s cloud solution for my future projects. I’m also planning on using the integrated CI/CD system. Since I’m going to use the cloud version I also want all my runners to be on the cloud (I don’t want to have to manage any self hosted VMs).

The CI quick start states that the Shared Runners run on Gitlab’s infrastructure , but the Runner docs only say that the Shared Runners are used for multiple projects.
What’s more the link to register a Shared Runner only explains how to do so with a self-hosted VM…

I looked at the available shared runners under Settings/CI/CD for one of my projects; what I noticed is none specify what linux distro they use and they all seem to have different software packages installed. Some don’t even have docker listed as an installed package. So how am I supposed to run my app’s tests if I can’t get a consistent VM/environment?

Here’s an image showing the inconsistent sets of packages installed on the shared runners:

I’d appreciate any help,