Support `AMD SEV-SNP` instances on GCP

[HuijingHei]

Feature Request

Currently we can create AMD SEV type confidential instances and run tests on GCP using kola. See
https://github.com/coreos/coreos-assembler/pull/3474

We should also support AMD SEV-SNP type confidential instances on GCP. See https://github.com/coreos/coreos-assembler/pull/3547

Desired Feature

• To create instances with AMD SEV, add option --gcp-confidential-type sev

• To create instances with AMD SEV-SNP, add option --gcp-confidential-type sev-snp

Other Information

To create instances with AMD SEV-SNP ,

• For gcloud command, should add alpha and --confidential-compute-type=SEV_SNP, like this:

gcloud alpha compute instances create example-instance \
  --confidential-compute-type=SEV_SNP \
...

• For api should contain confidentialInstanceType,

...
  "confidentialInstanceConfig": {
    "confidentialInstanceType": "SEV_SNP"
 }

The current api v1 is not yet supported for confidentialInstanceType , but in api alpha, should wait until it includes into v1.

[dustymabe]

@HuijingHei do we know if this statement is still the case today?

The current api v1 is not yet supported for confidentialInstanceType , but in api alpha, should wait until it includes into v1.

[HuijingHei]

@HuijingHei do we know if this statement is still the case today?

The current api v1 is not yet supported for confidentialInstanceType , but in api alpha, should wait until it includes into v1.

Yes, no confidentialInstanceType in latest v1, but in v0.alpha, I have no idea if there is any plan to be included in v1

[HuijingHei]

The latest v1 already includes ConfidentialInstanceType which supports "SEV_SNP", I think we can improve cosa to support it.