Call DescribeInstance in GetVMInfo

[haikuoliu]

Hi,

Right now the GetVMInfo API returns the VM info stored in firecracker-containerd runtime, but we want to check if the VM is responsive by invoking DescribeInstance (also cut another issue for implementing this) firecracker API, we could invoke firecracker API directly given that GetVMInfo returns firecracker socket, but I think it's probably better to invoke DescribeInstance in GetVMInfo API, and add the VM state in the response of GetVMInfo API. What do you think?

Thanks,
Haikuo

[samuelkarp]

Are you looking for information from the DescribeInstance API (like the state of the VM?) or are you trying to use this as a probe or health check?

[haikuoliu]

@samuelkarp I am trying to use it as a health check, to make sure both the firecracker-container shim and VM is responsive. We currently don't plan to use the state of VM or VM version as we are going to listen to the containerd events for the VM state, I guess it doesn't hurt to add VM state/VM version, but that depends on you.

[samuelkarp]

If you're looking for a health check, I wouldn't want to change the behavior of GetVMInfo but rather for us to expose something that's intended for a health check (CheckVMMConnection? Ping? Something like that).

Do you care about controlling things like connection/response timeout?

[haikuoliu]

A new API for checking VM connection sounds good, we don't really need a connection timeout parameter in the API, we can set a timeout for invoking CheckVMMConnection (or something similar) API.

[mxpv]

@samuelkarp I was thinking that we could extend GetVMInfo with a few additional fields from DescribeInstance - like state and vmm_version . This would be still a "VM Info" as well as a way of health checker (as we get state right from firecracker's response).

[haikuoliu]

We will do this with a privileged container, closing this issue.