VMSS Flex - Unable to set a load balancer probe for my scale set

Question

I am trying to enable application health monitoring and use a load balancer probe and it is not working.

Through the portal, I am able to select the probe but when I click save, the page refreshes and it is not enabled.

When I check the trace in my browser logs, I see the following response from :

{
  "error": {
    "details": [
      {
        "code": "InvalidJson",
        "message": "Could not find member 'healthProbe' on object of type 'VMNetworkProfile'. Path 'Properties.NetworkProfile.healthProbe', line 1, position 1227."
      }
    ],
    "code": "InvalidRequestFormat",
    "message": "Cannot parse the request."
  }
}

Is anyone else having issues? This scale set was created with Terraform using the "azurerm_orchestrated_virtual_machine_scale_set" resource.

Thank you.

Answer 1

Hello @Charles3828 ,

Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.

I understand that you are trying to enable application health monitoring by using a load balancer probe for your Virtual Machine Scale Sets in Flexible orchestration mode, but it is not working.

Application health via Load balancer health probe is currently NOT supported with Virtual Machine Scale Sets in Flexible orchestration mode.

Refer: https://learn.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-orchestration-modes#unsupported-parameters

For Flexible scale set instances, you must install and configure the Application Health Extension on the virtual machine to monitor application health.

Refer: https://learn.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-orchestration-modes#monitor-application-health

You can use Application Health Extension to monitor the application health of each instance in your scale set and perform instance repairs using Automatic Instance Repairs. There are two types of Application Health extension, Binary Health States or Rich Health States, to monitor the health of your applications deployed on Virtual Machine Scale Sets.

Binary Health States is generally available. Rich Health States is currently in public preview.

Refer: https://learn.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-health-extension?tabs=rest-api

Kindly let us know if the above helps or you need further assistance on this issue.

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