Restrict Default self-hosted Runner Labels

[Kerruba]

Currently, it is possible to add custom self-hosted runner labels to the runner-label checker using the following configuration:

self-hosted-runner:
    labels:
      - private-runner-label1
      - private-runner-label2

By default, the self-hosted label is considered a valid option for runners.

However, when using the Actions Runner Controller (ARC) to manage self-hosted runners on Kubernetes, it is not possible to assign multiple labels to the runner-set. Additionally, the default self-hosted label is not automatically added to the runner group in this setup.

As a result, the default self-hosted label often becomes an invalid option in such scenarios.

Proposal

It would be highly beneficial to provide an option in the configuration to restrict valid self-hosted runner labels to only those explicitly defined by the user.

For example, a new field could be introduced to disable the default acceptance of the self-hosted label unless explicitly included in the user-provided list.

This feature would improve compatibility with ARC and similar setups, ensuring labels are validated based on the user’s intended configuration.