node.js - How do you authenticate a VueJS app with Azure AD?

Question

I'm setting up an app using the VueJS 2.x framework and it needs to authenticate users via the Azure Active Directory service. I already have "login info" (Auth and Token URLs) neccessary for the service.

So far, I've only encountered one article that shows the setup in VueJS, but it relies on a third party service (Auth0) - adding uneccessary convolution in the process.

How do you proceed when there aren't any VueJS npm modules that allow for doing authenticating easily? Or do you have to rely on a library outside of Vue like Adal JS?

Any suggestions would be helpful.

Answer 1

To solve this very problem, I leaned on ADAL JS. I've made a Vue + Vue-Router sample application available here - but I'll include the important pieces below.

In your package.json:

"dependencies": {
    "adal-angular": "^1.0.15",
    "vue": "^2.5.2",
    "vue-router": "^3.0.1"
},

A basic wrapper module for the ADAL JS library:

import AuthenticationContext from 'adal-angular/lib/adal.js'

const config = {
  tenant: 'your aad tenant',
  clientId: 'your aad application client id',
  redirectUri: 'base uri for this application',
  cacheLocation: 'localStorage'
};

export default {
  authenticationContext: null,
  /**
   * @return {Promise}
   */
  initialize() {
    this.authenticationContext = new AuthenticationContext(config);

    return new Promise((resolve, reject) => {
      if (this.authenticationContext.isCallback(window.location.hash) || window.self !== window.top) {
        // redirect to the location specified in the url params.
        this.authenticationContext.handleWindowCallback();
      }
      else {
        // try pull the user out of local storage
        let user = this.authenticationContext.getCachedUser();

        if (user) {
          resolve();
        }
        else {
          // no user at all - go sign in.
          this.signIn();
        }
      }
    });
  },
  /**
   * @return {Promise.<String>} A promise that resolves to an ADAL token for resource access
   */
  acquireToken() {
    return new Promise((resolve, reject) => {
      this.authenticationContext.acquireToken('<azure active directory resource id>', (error, token) => {
        if (error || !token) {
          return reject(error);
        } else {
          return resolve(token);
        }
      });
    });
  },
  /**
   * Issue an interactive authentication request for the current user and the api resource.
   */
  acquireTokenRedirect() {
    this.authenticationContext.acquireTokenRedirect('<azure active directory resource id>');
  },
  /**
   * @return {Boolean} Indicates if there is a valid, non-expired access token present in localStorage.
   */
  isAuthenticated() {
    // getCachedToken will only return a valid, non-expired token.
    if (this.authenticationContext.getCachedToken(config.clientId)) { return true; }
    return false;
  },
  /**
   * @return An ADAL user profile object.
   */
  getUserProfile() {
    return this.authenticationContext.getCachedUser().profile;
  },
  signIn() {
    this.authenticationContext.login();
  },
  signOut() {
    this.authenticationContext.logOut();
  }
}

In the app's entry point (main.js if you used vue-cli):

import Vue from 'vue'
import App from './App'
import router from './router'
import authentication from './authentication'

// Init adal authentication - then create Vue app.
authentication.initialize().then(_ => {
  /* eslint-disable no-new */
  new Vue({
    el: '#app',
    router,
    template: '<App/>',
    components: { App }
  });
});

For your Vue router configuration:

import Vue from 'vue'
import Router from 'vue-router'
import HelloWorld from '@/components/HelloWorld'
import authentication from '../authentication'

Vue.use(Router)

const router = new Router({
  mode: 'history',
  routes: [
    {
      path: '/',
      name: 'HelloWorld',
      component: HelloWorld,
      meta: {
        requiresAuthentication: true
      }
    }
  ]
})

// Global route guard
router.beforeEach((to, from, next) => {
  if (to.matched.some(record => record.meta.requiresAuthentication)) {
    // this route requires auth, check if logged in
    if (authentication.isAuthenticated()) {
      // only proceed if authenticated.
      next();
    } else {
      authentication.signIn();
    }
  } else {
    next();
  }
});

export default router;

In your Vue components:

import authentication from './authentication'
...
computed: {
  isAuthenticated() {
    return authentication.isAuthenticated();
  }
},
methods: {
  logOut() {
    authentication.signOut();
  }
}

Add access token to request headers

The below is an example of a vue-resource http interceptor, but any method will do.

Vue.http.interceptors.push(function (request, next) {
  auth.acquireToken().then(token => {
    // Set default request headers for every request
    request.headers.set('Content-Type', 'application/json');
    request.headers.set('Ocp-Apim-Subscription-Key', 'api key');
    request.headers.set('Authorization', 'Bearer ' + token)
    // continue to next interceptor
    next();
  });
});

Hopefully this saves somebody a little time :)