Get EmberJS working with array of objects

I have a simple EmberJS app to list and show various objects.

My /servers.json API (for example) return this kind of format:

[
   {
      "hosted_domain" : "example.com",
      "status" : 1,
      "name" : "srv0443",
      "id" : 443
   },
   {
      "id" : 392,
      "status" : 1,
      "name" : "srv0392",
      "hosted_domain" : "example.com"
   },
   {
      "hosted_domain" : "example.com",
      "id" : 419,
      "name" : "srv0419",
      "status" : 1
   }
]

But I got the following error:

Assertion Failed: The response from a findAll must be an Array, not undefined

Ember expects this kind of format:

{
   "servers" : [
      {
         "name" : "srv0443",
         "status" : 1,
         "id" : 443,
         "hosted_domain" : "example.com"
      },
      {
         "status" : 1,
         "name" : "srv0392",
         "id" : 392,
         "hosted_domain" : "example.com"
      },
      {
         "status" : 1,
         "name" : "srv0419",
         "hosted_domain" : "example.com",
         "id" : 419
      },
  ]
}

I know I can override the payload with the extractArray of the RESTSerializer.

It's works by doing payload = { servers: payload } but how get it working in a generic way?

How can I do to catch the needed key of an Ember's controller?

In a more general way, what is the good REST format, by convention?

Thanks.