Add support for describeInstance

[haikuoliu]

Hi all,

Firecracker-containerd GetVMInfo API doesn't really call the VM API, we want to periodically call some VM API to check if instance is still responsive, we'd like to use describeInstance API for this purpose, but it doesn't seem it's implemented, do you have plan to implement it? Apologize ahead if you already done this.

Thanks,
Haikuo

[kzys]

Currently our Machine interface doesn't expose the underlying client, but we would do that. Please see the discussion on #116.

[kzys]

Another health check use-case. https://firecracker-microvm.slack.com/archives/CDL3FUR8B/p1572309553045800

[kzys]

#116 (comment)

I see that this work was scrapped in favor of providing a getter method for the inner client, I would be willing to implement if the change isn't already in progress.

I'm looking for a way to run a health check against a running VM and know that it is in the running state. Are there any existing solutions?

Hello @olibearo. I think that the definition of "healthy" depends on applications. For example, firecracracker-containerd is launching a small agent process inside a VM. So having a connection to the agent means "healthy" for firecracker-containerd. But other applications would have different definitions.

[mazzy89]

I'm interested to have a way to check the healthiness of the VM. In my case, I just run firecracker VMs inside a container. Similar to how Ignite does by spawning inside a Docker container a Firecracker VM so in my case I would need to implement a liveness/readiness endpoint that checks the status of the running VM.