fix(vm-image): Add Azure-specific configuration from Fedora Cloud SIG

[ddstreet]

There are some Azure-cloud-specific configuration settings needed to work with the specifics of the Azure cloud; the Fedora Cloud SIG has already done the work to determine the settings we want to use.

The specific changes include:

Enable openssh-server's keepalive; otherwise idle ssh connections appear to hang and/or are killed.

Enable use of Azure's PTP time source.

Add configuration to correctly handle Azure's non-standard way of providing accelerated networking, using two separate interfaces to represent a single SRIOV interface.

[ddstreet]

Add configuration to correctly handle Azure's non-standard way of providing accelerated networking, using two separate interfaces to represent a single SRIOV interface

This actually isn't needed for our base image, as it defaults to using systemd-networkd instead of NetworkManager; the workaround here is only for NetworkManager. With systemd-networkd, instances with accelerated networking do appear to work fine.

[reubeno]

@ddstreet If we do need some custom configs, would we not want to add an Azure-specific RPM that adds separate conf.d conf fragments rather than post-installing into the image? I've seen image post-install scripts get significantly abused in the past; they're harder to track, update, share, etc. too.

[ddstreetmicrosoft]

@ddstreet If we do need some custom configs, would we not want to add an Azure-specific RPM that adds separate conf.d conf fragments rather than post-installing into the image? I've seen image post-install scripts get significantly abused in the past; they're harder to track, update, share, etc. too.

that's probably better, yeah, i was just duplicating the approach that the fedora cloud sig took in their image generation.

This should probably go into an identity sub-package like azurelinux-release-identity-cloud-azure or something similar, but I'll leave this PR open as draft until we get that set up