balena deployment of self-hosted GitHub runners
Runners are deployed in two variants, vm and container, where vm is isolated and safe to use on public repositories.
See github-runner-vm and self-hosted-runners for image sources.
Firecracker allows overprovisioning or oversubscribing of both CPU and memory resources for virtual machines (VMs) running on a host. This means that the total vCPUs and memory allocated to the VMs can exceed the actual physical CPU cores and memory available on the host machine.
In order to make the most efficient use of host resources, we want to slightly overprovision the host hardware so if/when all allocated resources are consumed by jobs (e.g. yocto) there would be minimal overlap that could lead to performance degredation.
See the github-runner-vm README for more.