I think GP got confused, it's not running the runners locally, it's running the CI steps locally (see the other sibling replies).
For example, running tests locally exactly the same way as in the runner - sometimes I have to open a debugger in the middle of a test to see what exactly went wrong. Our tests run in gitlab in a particular docker image, and I've been adding a "make test" that runs the same tests in the same image locally, with additional flags to have full interactivity so the debugger works if needed.
The local ones, mentioned in the original comment that we've been discussing in this thread? The local runner, executing on the developer's machine.
Of course it makes no difference whether that runner runs on our local CI host or on my dev machine.
I think GP got confused, it's not running the runners locally, it's running the CI steps locally (see the other sibling replies).
For example, running tests locally exactly the same way as in the runner - sometimes I have to open a debugger in the middle of a test to see what exactly went wrong. Our tests run in gitlab in a particular docker image, and I've been adding a "make test" that runs the same tests in the same image locally, with additional flags to have full interactivity so the debugger works if needed.