You can use $brooklyn:external directly:

{% highlight yaml %} name: MyApplication brooklyn.config: example: $brooklyn:external(“supplier”, “key”) {% endhighlight %}

or embed the external function inside another $brooklyn DSL function, such as $brooklyn:formatString:

{% highlight yaml %} name: MyApplication brooklyn.config: example: $brooklyn:formatString(“%s”, external(“supplier”, “key”)) {% endhighlight %}