MacOS: Lima default to vz/virtiofs and skip install QEMU

[GlassOfWhiskey]

Description

MacOS 13 and newer support the vz driver for Lima virtual machines, based on the Apple Virtualization Framework, which offers improved performance and increased stability. In addition, it supports the virtiofs volume driver, which is faster than the default QEMU-based I/O driver.

Even if it is possible to use this stack by explicitly configuring the LIMA_START_ARGS environment variable, it would be nice to have them enabled by default, using QEMU only if the user explicitly requires it for any reason. In addition, this configuration would allow to skip the QEMU installation by default, as it is not required by the vz/virtiofs stack.

[kayabaNerve]

GitHub-hosted CI runners do not support nested virtualization AFAIK, so I don't believe this would work in an action unless someone hosted a runner on better hardware than GitHub offers. That'd imply it should be opt-in, or enabled when supported by the CPU, but not by default, outright.

[GlassOfWhiskey]

Hi @kayabaNerve, what you say is true for ARM-based runners, which seems to be unsupported by the whole action as per the README.md. However, Intel-based runners do support nested virtualization, and on them the vz/virtiofs works correctly. I am already using it in my GitHub workflows (e.g., on the StreamFlow repo). If you don't want to put them as the default stack, at least having an option that configures them and prevents the action from installing QEMU in that case would be really appreciated.

[kayabaNerve]

Thanks for clarifying the -intel runners do. In that case, I'd consolidate to my comment that they should enabled-by-default when supported, not unilaterally. I'll also likely adjust my own -intel CIs with this bit of advice 😅

As for ARM-based runners, I do use those in my work with this action. It just requires an environment variable, as using vz does with your own example.