[QUERY] How to use custom script extensions with Azure.ResourceManager.Compute?

[guythetechie]

TLDR
I'm at a loss on how to set VirtualMachineScaleSetExtension.Setting in order to run custom script extensions.

Query/Question
I'm trying to create a scaleset with a custom script extension. The equivalent ARM template section would be:

"extensionProfile": {
    "extensions": [
        {
            "name": "customScript",
            "properties": {
                "publisher": "Microsoft.Compute",
                "settings": {
                    "fileUris": [
                        "https://mysite.com/agent.exe"
                    ],
                    "commandToExecute": "agent.exe --parameter1 \"value\""
                },
                "typeHandlerVersion": "1.10",
                "autoUpgradeMinorVersion": true,
                "type": "CustomScriptExtension"
            }
        }
    ]
}

I can't seem to find a way to do something similar with the new Azure.ResourceManager.Compute library.

var scaleSet = new VirtualMachineScaleSet(location)
{
    DoNotRunExtensionsOnOverprovisionedVMs = true,
    // ...
    VirtualMachineProfile = new VirtualMachineScaleSetVMProfile
    {
        ExtensionProfile = new VirtualMachineScaleSetExtensionProfile
        {
            Extensions = new List<VirtualMachineScaleSetExtension>
            {
                new VirtualMachineScaleSetExtension
                {
                    Name = "customScript",
                    Publisher = "Microsoft.Compute",
                    Settings = ??? // How do I set this?
                    TypeHandlerVersion = "1.10",
                    AutoUpgradeMinorVersion = true,
                    TypePropertiesType = "CustomScriptExtension"
                }
            }
        }
    }
};

I've tried using an anonymous object, but this fails with a NotSupportedException:

Settings = new
{
    fileUris = new List<string>
    {
        fileUrl
    },
    commandToExecute = commandToExecute
}

I've also tried just passing a JSON string - the scaleset gets created, but the extension fails because the JSON isn't formatted properly. This code

Settings = $"{{\"fileUris\": [\"{fileUrl}\"], \"commandToExecute\": \"{commandToExecute}\"}}"

returns this setting (note the extra quote the beginning and end)

as opposed to this desired setting

I looked at the SDK serialization code (here and here) and found that it does this, which explains my results:

public static void WriteObjectValue(this Utf8JsonWriter writer, object value)
{
    switch (value)
    {
        //..
        case IUtf8JsonSerializable serializable:
            writer.WriteObjectValue(serializable);
            break;
        //..
        case string s:
            writer.WriteStringValue(s);
            break;
        //..
        default:
            throw new NotSupportedException("Not supported type " + value.GetType());
    }
}

So I tried writing a small CustomScriptSettings class that implements IUtf8JsonSerializable, but that interface is internal.

I understand this is still in preview, so this scenario might just not have been fully implemented yet.

Thanks!

Environment:

• Name and version of the Library package used: Azure.ResourceManager.Compute 1.0.0-preview.1]

[erich-wang]

Thanks for raising the question, we're looking into it.

[guythetechie]

Thanks for raising the question, we're looking into it.

Thank you. Any updates?

[guythetechie]

Thanks for raising the question, we're looking into it.

Thank you. Any updates?

Sorry, I accidentally closed this - reopening.

[keflem]

Hi @guythetechie! I ran across this while searching for the exact same thing. The answer isn't very intuitive, but if you use JObject you can get the Settings to work. Example:

   Settings = JObject.FromObject(new
   {
      fileUris = new string[] { scriptToRun },
      commandToExecute
   });

[allenjzhang]

@guythetechie , please let us know if above code sample does not work for you. Thanks.