providers/vultr: Add Vultr provider

[dghubble]

• Add Vultr as a provider, user-data can be an Ignition config
• Metadata endpoint is http://169.254.169.254/user-data/user-data

Background:

Hi! 👋 I've been using Fedora CoreOS on Vultr for some time. Using the installer ISO crashing to an emergency shell to supply a shim Ignition config that points to Vultr metadata server's user-data to create an image that will boot with Ignition on Vultr. Recently the Fedora CoreOS installer ISO seems to have been removed, so I'd like to add proper support.

[coreosbot]

Can one of the admins verify this patch?

[arithx]

LGTM

[arithx]

ok to test

[lucab]

@dghubble thanks for the PR!
There a few other things that likely need some more glueing work (documenting the platform ID, teaching coreos-assembler how to build the image, plumbing the artifacts through the pipeline, teaching afterburn about additional metadata/ssh-keys), not sure how much of that you want to do yourself.
Perhaps we should open an umbrella ticket at https://github.com/coreos/fedora-coreos-tracker and coordinate that way?

[jlebon]

Yeah, we need to discuss first whether we want to support this cloud. How "vanilla" is it? If it's just a matter of restamping a disk image with its platform ID, then that's easier to justify. But if there are other platform requirements that could cause a higher maintenance burden, that changes things. Though from what you're saying, it's been working fine as is apart from the user-data bits?

Anyway, agreed re. filing a tracker ticket to discuss this first!

[dghubble]

Thanks for the comments, I've filed coreos/fedora-coreos-tracker#355 to discuss

[jlebon]

LGTM!