Don't delete AppSettings not declared in a template : <p>When deploying an <strong>Azure Function App</strong> and <strong>AppSettings</strong> via an <strong>ARM Template</strong>, is it possible to tell Azure not to delete <strong>AppSettings</strong> that are not declared in the template?</p>

<p>For example, take the following <strong>AppSettings</strong> config from the template and imagine that I'm updating an existing <strong>Function App</strong>.  In this case, an <strong>AppSetting</strong> called <strong>storageaccountname_STORAGE</strong> would be deleted, which is undesirable as (for example) it has been created to facilitate a binding.</p>

<pre><code>{
    "apiVersion":"2016-08-01",
    "name":"appsettings",
    "type":"config",
    "dependsOn":[
        "[resourceId('Microsoft.Web/Sites/Slots', variables('functionAppName'), 'Staging')]"
    ],
    "properties":{
        "AzureWebJobsStorage":"[concat('DefaultEndpointsProtocol=https;AccountName=', variables('storageAccountName'), ';AccountKey=', listkeys(resourceId('Microsoft.Storage/storageAccounts', variables('storageAccountName')), '2015-05-01-preview').key1, ';')]",
        "AzureWebJobsDashboard":"[concat('DefaultEndpointsProtocol=https;AccountName=', variables('storageAccountName'), ';AccountKey=', listkeys(resourceId('Microsoft.Storage/storageAccounts', variables('storageAccountName')), '2015-05-01-preview').key1, ';')]",
        "APPINSIGHTS_INSTRUMENTATIONKEY":"[reference(resourceId('Microsoft.Insights/components', variables('applicationInsightsName')), '2014-04-01').InstrumentationKey]",
        "FUNCTION_APP_EDIT_MODE":"readwrite",
        "FUNCTIONS_EXTENSION_VERSION":"~1",
        "WEBSITE_CONTENTAZUREFILECONNECTIONSTRING":"[concat('DefaultEndpointsProtocol=https;AccountName=', variables('storageAccountName'), ';AccountKey=', listkeys(resourceId('Microsoft.Storage/storageAccounts', variables('storageAccountName')), '2015-05-01-preview').key1, ';')]",
        "WEBSITE_CONTENTSHARE":"[toLower(variables('functionAppName'))]",
        "WEBSITE_NODE_DEFAULT_VERSION":"6.5.0"
    }
}
</code></pre>

<p>Is there a way to selectivly set <strong>AppSettings</strong> via an <strong>ARM Template</strong>, or are the templates simply not capale of functioning as desired for such a scenario?</p>
