OCPBUGS-57603: Disallow cross subscription encryption sets

[rna-afk]

Since CAPZ does not support using encryption sets in a subscription not in the current subscription, adding a validation to return error if the subscriptions don't match.

[openshift-ci-robot]

@rna-afk: This pull request references Jira Issue OCPBUGS-57603, which is invalid:

• expected the bug to target the "4.22.0" version, but no target version was set

Comment /jira refresh to re-evaluate validity if changes to the Jira bug are made, or edit the title of this pull request to link to a different bug.

The bug has been updated to refer to the pull request using the external bug tracker.

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In response to this:

Since CAPZ does not support using encryption sets in a subscription not in the current subscription, adding a validation to return error if the subscriptions don't match.

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@rna-afk: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/e2e-azurestack	2a64205	link	false	/test e2e-azurestack
ci/prow/azure-ovn-marketplace-images	2a64205	link	false	/test azure-ovn-marketplace-images
ci/prow/e2e-aws-ovn	2a64205	link	true	/test e2e-aws-ovn
ci/prow/e2e-azure-ovn-shared-vpc	2a64205	link	false	/test e2e-azure-ovn-shared-vpc

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[rna-afk]

/jira refresh

[openshift-ci-robot]

@rna-afk: This pull request references Jira Issue OCPBUGS-57603, which is valid. The bug has been moved to the POST state.

3 validation(s) were run on this bug

• bug is open, matching expected state (open)
• bug target version (4.22.0) matches configured target version for branch (4.22.0)
• bug is in the state ASSIGNED, which is one of the valid states (NEW, ASSIGNED, POST)

Requesting review from QA contact:
/cc @jinyunma

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/jira refresh

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[jinyunma]

pre-merge test passed.

/verified by jima

[openshift-ci-robot]

@jinyunma: This PR has been marked as verified by jima.

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pre-merge test passed.

/verified by jima

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[patrickdillon]

Nice work figuring this out!

To summarize what we discussed: cross-subscription Disk Encryption Sets are not supported, but users can use a key vault from another subscription to create the DES.

Can you update the bug to indicate that as the recommended path for the bug reporter? It seems like that should immediately unblock them (although we will probably still need to deal with the managed key used to encrypt bootstrap ignition, but that is a separate bug).

I think there are a few more things we should do to improve the experience surrounding this API:

• I don't think we should deprecate the field (although I could be convinced), but we should generally discourage users from using it. Can you update the field doc text to indicate: "Azure does not support cross-subscription disk-encryption sets. By default, the subscription from the installer credentials will be used. Therefore, setting this field is unnecessary."
• Then we need to follow up on this promise of setting the defaults. We're already doing it in one place (more on that in a moment), but not in the machine manifests. Can you follow this pattern so that the default is set in the install config itself, and will be used everywhere:
  

  installer/pkg/asset/installconfig/installconfig.go

  Line 126 in 435db5e

  func (a *InstallConfig) finishGCP() error {

Basically you just need to create an Azure finish function wherfe if disk encryption is set, and subscription is empty, add the subscription from the creds.

• Finally we can simplify the one code instance where the default is set, because it will be redundant:

installer/pkg/asset/manifests/clustercsidriver.go

Lines 75 to 82 in 435db5e

	subscriptionID := platform.OSDisk.DiskEncryptionSet.SubscriptionID
	if subscriptionID == "" {
	session, err := installConfig.Azure.Session()
	if err != nil {
	return errors.Wrap(err, "could not get azure session")
	}
	subscriptionID = session.Credentials.SubscriptionID
	}

[patrickdillon]

CAPZ is an implementation detail here, so we wouldn't want to mention it by name. Also the restriction is in Azure

Suggested change

	return nil, fmt.Errorf("different subscription from resource group subscription. CAPZ does not support cross subscription encryption sets")
	return nil, fmt.Errorf("different subscription from resource group subscription. Azure does not support cross subscription encryption sets")

[jinyunma]

but users can use a key vault from another subscription to create the DES.

@patrickdillon I tested with az command, this is also disallowed in Azure.

What I tested:

1. created keyvault/key in subscription A, then created DES using this keyvault/key in subscription B, all of them were in the same region.
   Result: DES was created failed.

% az disk-encryption-set create -n $DISK_ENCRYPTION_SET_NAME -l $LOCATION -g $RESOURCEGROUP --source-vault $KEYVAULT_ID --key-url $KEYVAULT_KEY_URL
(InvalidParameter) The SubscriptionId:"53b8f551-f0fc-4bea-8cba-6d1fefd54c8a" of the request must match the SubscriptionId "8cbff7ff-5103-4cc2-b691-abbee101e1d0" contained in the Key Vault Id.
Code: InvalidParameter
Message: The SubscriptionId:"53b8f551-f0fc-4bea-8cba-6d1fefd54c8a" of the request must match the SubscriptionId "8cbff7ff-5103-4cc2-b691-abbee101e1d0" contained in the Key Vault Id.
Target: diskEncryptionSet.properties.activeKey.sourceVault.id

2. created keyvault/key/DES in subscription A, create VM in subscription B with DES configured.
   Result: VM created failed, same as bug description.

% az vm create --name jima-vm --resource-group jima-test-rg --image RedHat:RHEL:8-lvm-gen2:8.6.2022051814  --size Standard_D8s_v3 --admin-username core --ssh-key-values <key.pub> --os-disk-encryption-set $DES_RESOURCE_ID
{"status":"Failed","error":{"code":"DeploymentFailed","target":"/subscriptions/53b8f551-f0fc-4bea-8cba-6d1fefd54c8a/resourceGroups/jima-test-rg/providers/Microsoft.Resources/deployments/vm_deploy_Imxll7mR1VkSg8NKFYQxkQ0v8HuEUWxv","message":"At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/arm-deployment-operations for usage details.","details":[{"code":"BadRequest","target":"CRP disk id 9bcbbd01-07b6-4c41-909b-626a2268230b","message":"DiskEncryptionSet '/subscriptions/8cbff7ff-5103-4cc2-b691-abbee101e1d0/resourceGroups/jima-test-rg/providers/Microsoft.Compute/diskEncryptionSets/jima-des' was not found."}]}}

So look like that Azure doc is misleading, that's not TRUE!
"Azure Key Vaults may be used from a different subscription but must be in the same region as your disk encryption set. "
DES, keyvault, VM and disk should be in the same subscription.