Define attribute in role using another attribute's value

Hello, I'm working with the Datadog cookbook from the supermarket and I'm trying to configure checks using the different recipes included. One recipe has me specifying the host using an attribute. I want the fqdn of the node where the recipe is used to be the host. The attribute I'm editing is:
'datadog' => {
'sqlserver' => {
'instances' => [
'host' =>
As I said I want the 'host' value to be the fqdn. I have tried 'host' => "#{node['fqdn']}" but I get the following error: undefined local variable or method `node'
Am I using incorrect syntax in defining this in the node? Or is this something that is even possible in a role?

This is not possible in a role.