Self hosted runners: make VM image configurable through environment variable

The image SKU was hidden a bit in the azure-arm-template.json. Let's
make it more visible by turning it into a parameter that the CI pipeline
can provide.

Signed-off-by: Dennis Ameling <[email protected]>

Author: dennisameling

.github/workflows/create-azure-self-hosted-runners.yml

@@ -39,6 +39,7 @@ env:
   # For more information, see https://learn.microsoft.com/en-us/azure/virtual-machines/dplsv5-dpldsv5-series (which
   # unfortunately does not have more information about price by region)
   AZURE_VM_REGION: westus2
+  AZURE_VM_IMAGE: win11-22h2-ent
 
 # The following secrets are required for this workflow to run:
 # AZURE_CREDENTIALS - Credentials for the Azure CLI. It's recommended to set up a resource
@@ -130,6 +131,7 @@ jobs:
           githubActionsRunnerRegistrationUrl="$ACTIONS_RUNNER_REGISTRATION_URL"
           githubActionsRunnerToken="$ACTIONS_RUNNER_TOKEN"
           postDeploymentPsScriptUrl="$POST_DEPLOYMENT_SCRIPT_URL"
+          virtualMachineImage="$AZURE_VM_IMAGE"
           virtualMachineName="${{ steps.generate-vm-name.outputs.vm_name }}"
           virtualMachineSize="$AZURE_VM_TYPE"
           publicIpAddressName1="${{ steps.generate-vm-name.outputs.vm_name }}-ip"

azure-self-hosted-runners/azure-arm-template.json

@@ -81,6 +81,9 @@
         "osDiskDeleteOption": {
             "type": "string"
         },
+        "virtualMachineImage": {
+            "type": "string"
+        },
         "virtualMachineSize": {
             "type": "string"
         },
@@ -209,7 +212,7 @@
                     "imageReference": {
                         "publisher": "microsoftwindowsdesktop",
                         "offer": "windows11preview-arm64",
-                        "sku": "win11-22h2-ent",
+                        "sku": "[parameters('virtualMachineImage')]",
                         "version": "latest"
                     }
                 },