App.js

import {Router} from 'aurelia-router';
import bootstrap from 'bootstrap';
import {EventAggregator} from 'aurelia-event-aggregator';


export class App {
  static inject() { return [ Router, EventAggregator ];}
  constructor(router, ea) {
    this.router = router;
    this.isLoggedIn = false;
    this.ea = ea;

    var test  = "Welcome";
    this.router.configure(config => {
      config.title = 'Aurelia';
      config.addPipelineStep('authorize', AuthorizeStep);
      config.map([
        { route: ['','welcome'],  moduleId: './welcome',      nav: true, title:test },
        { route: 'flickr',        moduleId: './flickr',   auth: true,    nav: true },
        { route: 'login',        moduleId: './login',   nav: false },
        { route: 'child-router',  moduleId: './child-router', nav: true, title:'Child Router' }
      ]);
    });

    this.ea.subscribe('login', (credentials) => {
      if(credentials.username === 'test' &&
        credentials.pass === 'pass')
        this.isLoggedIn = true;
      this.router.navigate('flickr');
    });
  }
}

class AuthorizeStep {

  static inject(){
    return [App];
  }

  constructor(app){
    this.app = app;
  }

  run( routingContext, next ) {

    if( routingContext.nextInstructions.some( i => i.config.auth ) ) {
      if( !this.app.isLoggedIn ) {
        routingContext.router.navigate('login');
        return next.cancel();
      }
      return next();
    } else {
      return next();
    }
  }
}

login.js

import {EventAggregator} from 'aurelia-event-aggregator';

export class Login {
  static inject() { return [EventAggregator]; }
  constructor(ea) {
    this.ea = ea;

  }

  doLogin() {
    this.ea.publish('login', { username: 'test', pass: 'pass' });
  }
}