rules/conditions/Azure/appServices/isFunctionApp.json

{
    filter: [
        {
            conditions : [
                [
                    "kind",
                    "match",
                    "^(functionapp)(,linux)?$"
                ],
                [
                    "type",
                    "match",
                    "^Microsoft\\.Web/sites$"
                ]
            ],
            "operator":"and"
        }
    ]
}