Add support for the metadata service in ignite run

[luxas]

Firecracker has a metadata service that allows for passing arbitrary JSON data to the VM, where it client-side can be fetched from a hardcoded 169.254.169.254 IP endpoint.

We should allow the user to specify this metadata at runtime.

[patrobinson]

Wouldn't it be better to expose firecracker.sock say at /var/lib/firecracker/vm/$id/firecracker.sock?
This way you could dynamically update the metadata and access other features of the Firecracker API.

[luxas]

Yes, that is also a good idea (approved #132 😄), but at VM start time (IIRC), you need to set whether the MMDS should be enabled or not, and by default we have it disabled for less resource usage.
So we'd most probably like to expose some high-level knob to set the data, too

[patrobinson]

@luxas oh cool, I'll work on that next

[luxas]

Thank you @patrobinson ✨! Let us know if you need any help.

[luxas]

Hi @patrobinson 👋 any progress here? Do you want help on getting this up and running?

[patrobinson]

I had a look at this but it wasn't trivial. It's not currently a focus for me sorry.

[luxas]

Ok, no problem. Would you like some smaller work item to help out on @patrobinson instead or are you too busy at the moment?

[patrobinson]

Thanks @luxas for being so forthcoming, but at this stage I'm not looking to actively contribute. That may change in the future and I'll let you know.

[luxas]

Gotcha. No problem 😄!

[alexeldeib]

@luxas what are you thinking here? user passes in json on vm creation and that gets applied with a PUT after VM is up, or introducing an ignite CLI command to pass through arbitrary data to MMDS? Or something else?

[alexeldeib]

I started on this 😄 Would appreciate guidance though

[luxas]

Thanks! I'll comment on the PR 👍