How to output the IP address of an App Service deployed via ARM Template

I would like the public IP address from an App Service deployed from an ARM Template like the simplified one below. I've seen examples of getting the public inbound IP address from an API Gateway, VNET of a VM, App Service Environment, etc., but I haven't found anything that indicates how to get it out of a simple App Service deployment. I find navigating the ARM API, and how that translates into a string into a JSON file, rather byzantine. Any assistance would be appreciated.

{
    "$schema": "http://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
    "contentVersion": "1.0.0.0",
    "parameters": {
        "appServiceName": {
            "type": "string",
            "minLength": 1,
            "metadata": {
                "description": "Specifies the name of the Azure App Service"
            }
        },
        "appServicePlanName": {
            "type": "string",
            "minLength": 1
        }
    },
    "variables": {
    },
    "resources": [
        {
            "apiVersion": "2015-08-01",
            "name": "[parameters('appServiceName')]",
            "type": "Microsoft.Web/sites",
            "kind": "app",
            "location": "[resourceGroup().location]",
            "dependsOn": [],
            "properties": {
                "serverFarmId": "[resourceId('Microsoft.Web/serverfarms', parameters('appServicePlanName'))]",
                "clientAffinityEnabled": false
            },
            "resources": [],
        }
    ],
    "outputs": {
        "appServiceName": {
            "type": "string",
            "value": "[parameters('appServiceName')]"
        },
        "ipAddress": {
            "type": "string",
            "value": "whatingodsnamegoeshere"
        }
    }
}

Solution

you need to use reference() function and give it resource id or just the name if the resource is in the same template:

reference(parameters('appServiceName'), '2016-03-01', 'Full').properties.inboundIpAddress

or with resourceId():

reference(resourceId('Microsoft.Web/serverfarms', parameters('appServicePlanName')), '2016-03-01', 'Full').properties.inboundIpAddress