enableAutomaticOSUpgrade on existing VMSS

Question

I am following the steps on this page to apply automatic OS upgrades to my virtual machine scale set: https://learn.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-automatic-upgrade

We are doing this for our test environment Service Fabric cluster, and our durability level is Bronze. We deployed with this upgrade policy in our ARM template:

"upgradePolicy": {
          "mode": "Automatic",
          "rollingUpgradePolicy": {
            "maxBatchInstancePercent": 20,
            "maxUnhealthyInstancePercent": 20,
            "maxUnhealthyUpgradedInstancePercent": 20,
            "pauseTimeBetweenBatches": "PT0S"
          },
          "automaticOSUpgradePolicy": {
            "enableAutomaticOSUpgrade": true,
            "disableAutomaticRollback": false
          }
        }

But while deploying, we saw this error:

New-AzResourceGroupDeployment : 3:59:40 PM - The deployment 'serviceFabricArmTemplate' failed with error(s). Showing 1
out of 1 error(s).
Status Message: Automatic OS Upgrade is not supported for this Virtual Machine Scale Set because a health probe is not
applied to all instances. Apply the health probe to all instances in the Virtual Machine Scale Set while property
'upgradePolicy.automaticOSUpgradePolicy.enableAutomaticOSUpgrade' is false and then update property
'upgradePolicy.automaticOSUpgradePolicy.enableAutomaticOSUpgrade' to true. (Code:BadRequest)
CorrelationId: 67ac9434-dcc9-46ab-b074-6ed1bc6410b3

So, I applied a health probe, set enableAutomaticOSUpgrade to false, and re-deployed. That deployment succeeded. Following the directions from the error message above, I changed enableAutomaticOSUpgrade back to true. However, when deploying again I saw this error:

New-AzResourceGroupDeployment : 4:07:57 PM - The deployment 'serviceFabricArmTemplate' failed with error(s). Showing 1
out of 1 error(s).
Status Message: Service Fabric and Virtual Machine Scale Set have mismatch in value of
'upgradePolicy.automaticOSUpgradePolicy'.  Virtual Machine Scale Sets should have 'False' set as the value of
'upgradePolicy.automaticOSUpgradePolicy'.  (Code:OperationNotAllowed)
CorrelationId: 8d904f91-91b6-4589-a028-8510d0542352

Do I need to stop the VMSS first, then re-deploy for this change to go into effect?

Answer 1

@Cathleen Kong (SHE/HER)

I believe the issue is due to Service Fabric being Bronze tier. You can see the requirements for Service Fabric here.

• Service Fabric durability level is Silver or Gold. If Service Fabric durability is Bronze, only Stateless-only node types support automatic OS image upgrades).
• The Service Fabric extension on the scale set model definition must have TypeHandlerVersion 1.1 or above.
• Durability level should be the same at the Service Fabric cluster and Service Fabric extension on the scale set model definition.
• An additional health probe or use of application health extension is not required for Silver or Gold durability. Bronze durability with Stateless-only node types requires an additional health probe.
• The property virtualMachineProfile.osProfile.windowsConfiguration.enableAutomaticUpdates property must set to false in the scale set model definition. The enableAutomaticUpdates property enables in-VM patching using "Windows Update" and is not supported on Service Fabric scale sets.

Ensure that durability settings are not mismatched on the Service Fabric cluster and Service Fabric extension, as a mismatch will result in upgrade errors. Durability levels can be modified per the guidelines outlined on this page.

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