Missing vm image features on Azure since publishing with CommunityGalleries

What happened:

VM Images on Azure have guest os features that specify what the OS can do.

E.g. from a SUSE cHost Image:

$ az vm image show --urn suse:sles-15-sp5-chost-byos:gen2:2024.03.07
{
  [...]
  "features": [
    {
      "name": "SecurityType",
      "value": "TrustedLaunchSupported"
    },
    {
      "name": "IsAcceleratedNetworkSupported",
      "value": "True"
    },
    {
      "name": "DiskControllerTypes",
      "value": "SCSI, NVMe"
    },
    {
      "name": "IsHibernateSupported",
      "value": "True"
    }
  ],
  [...]
}

The feature IsAcceleratedNetworkSupported is of notable interest since Garden Linux supports it and it is actively used in Gardener. However, it was never set to true even during times when Garden Linux published through Azure Marketplace:

$ az vm image show --urn sap:gardenlinux:greatest:934.11.0
{
  [...]
  "features": [
    {
      "name": "IsAcceleratedNetworkSupported",
      "value": "False"
    },
    {
      "name": "DiskControllerTypes",
      "value": "SCSI"
    },
    {
      "name": "IsHibernateSupported",
      "value": "False"
    }
  ],
  [...]
}

Setting the feature list is done in the galleryImageDefinition by providing a features element (ref, ref) containing allowed features.

Things to do:

[ ] figure out which features are actually supported by Garden Linux
[ ] test if a gallery image definition can be retroactively changed without affecting already published images (i.e. test in a non-productive subscription)
[ ] obtain a list of possible features that can be specified in the gallery image definition
[ ] add features that are supported by Garden Linux to the gallery image definition (might be a different feature set for gen1 and gen2 definitions)

gardenlinux / glci

Missing vm image features on Azure since publishing with CommunityGalleries #58