Azure: doesn't set hostname

[serbrech]

Bug

Afterburn does not set the hostname on Azure.

Operating System Version

RHCOS

Afterburn Version

master

Environment

Azure

Expected Behavior

/etc/hostname contains the machine name defined on Azure

Actual Behavior

no file

Other Information

curl http://169.254.169.254/metadata/instance/compute/name?api-version=2017-08-01&format=text gives you the hostname

file location should be /etc/hostname

Currently Azure provider returns None:

afterburn/src/providers/azure/mod.rs

Lines 413 to 415 in 7db2aff

	fn hostname(&self) -> Result<Option<String>> {
	Ok(None)
	}

[serbrech]

@jpang @imcleod @awesomenix

[lucab]

I seem to remember the Azure DHCP is able to hand out the hostname to a node via DHCP (Option-12, possibly), which would be the reason why Afterburn doesn't have to take care of that.

Is either the DCHP client not asking/handling that option, or the server not providing it?

[bgilbert]

I tried it, and Azure DHCP apparently is not sending the hostname when requested to. On Container Linux I think WALinuxAgent is setting the hostname. So implementing in Afterburn and running that in the initramfs seems like the right approach.

[lucab]

Then I was mixing up with some other cloud provider, and we have indeed to add such logic to Afterburn.

While I didn't see a JSON schema for the metadata response, there are comprehensive examples and docs at https://docs.microsoft.com/en-us/azure/virtual-machines/windows/instance-metadata-service#getting-more-information-about-the-vm-during-support-case. As we don't care about other properties in there for the moment, the individual textual-format field is probably a better target to consume.

For completeness, this seems to cover host name only (not node FQDN).