I'm using buildkite - which lets me run the workers myself. These are long-lived Ubuntu systems setup with the same code we use on dev and production running all the same software dependencies. Tests are fast and it works pretty nice.
You mean Docker-in-Docker? If so, we used Kaniko to build images without Docker-in-Docker
Using Kaniko also doesn't solve for:
How do you run containers within that build in order to test them? How do you run KinD/K3s within that build to validate the containers e2e?
We test our containers in our Dev environment after deploying
This also comes to mind: "root in the container is root on the host" - https://suraj.io/post/root-in-container-root-on-host/