New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

controllers.index.js

import Ember from 'ember';

export default Ember.Controller.extend({
  serverConfig: Ember.inject.service(),
  config: Ember.computed.alias('serverConfig.config')
  
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  
  serverConfig: Ember.inject.service(),
  
  init() {
    this._super(...arguments);
    
    Ember.$.mockjax({
      url: '/api/config',
      responseText: {
        foo: 'bar',
        test1: 'This is test1 value',
        test2: 'This is test2 value'
      }
    });
  },
  
  beforeModel() {
    return this.get('serverConfig').initialize();
  }
  
});

services.server-config.js

import Ember from 'ember';

export default Ember.Service.extend({
  
  config: undefined,
  
  initialize() {
    var self = this;
    return Ember.$.ajax({
      type: 'GET',
      url: '/api/config'
    }).done(function(response) {
      self.set('config', response);
    });
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

templates.index.hbs

<h3>Server variables:</h3>

<p>foo: {{config.foo}}</p>
<p>test1: {{config.test1}}</p>
<p>test2: {{config.test2}}</p>

twiddle.json

{
  "version": "0.8.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.5.1",
    "ember-data": "2.5.2",
    "ember-template-compiler": "2.5.1",
    "jquery-mockjax": "https://cdnjs.cloudflare.com/ajax/libs/jquery-mockjax/1.6.2/jquery.mockjax.js"
  }
}