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This project is a demonstration about how to use multivocal to do authentication and authorization with Actions on Google and Google Sign In.

If you've looked at the previous two examples (multivocal-example-auth0 and multivocal-example-auth1), you'll see that this one is a lot more complicated. It is trying to do more - both authentication and authorization. So we both want to know who this user is and then get permission to do something on their behalf (in this case, count how many files they have in Google Drive).

Users can't authorize you to access their account using voice alone. They will need to be directed to a website where they will be able to authorize OAuth scopes that your project needs.

Before you code

Before we begin coding, there is a lot of setup we'll need. (Much of this setup is stuff we need if we were setting up Sign-In for a web page, so it may be familiar, but we have a few more settings to deal with.)


  • A project in the Action Console. This also gives us a project in the Google Cloud Console, which we'll be using. They must be the same project.
  • We will use Firebase for Cloud Functions, the Real-Time Database, and for hosting the web page for sign-in.
    • Changes for Google Cloud Functions, AWS Lambda, or other node.js hosting platforms are possible, but are left as an exercise for the reader.
    • We're using the Firebase Real-Time Database to store user information. You can substitute another database or data store instead, but we're doing it this way because the integration is significantly easier.
    • Using something besides Firebase Hosting is also possible, but you may need to deal with cross-site restrictions.
  • For this example, check the project out from github: git clone

Setup Actions on Google and Dialogflow

There are a few things we'll need to configure in both the Actions on Google console and in the Dialogflow console.

Load Multivocal Intents into Dialogflow

Make sure you have already loaded the multivocal standard intents. We need to do this now because we need the Welcome Intent to be defined for our next step.

Unlike some of our previous examples, we won't be defining any additional Intents.

Enable Linking for the Welcome Intent

The authorization process mostly takes place on a web page, since OAuth authorization requires the user to grant permission through a web page.

Once that is complete, we'll have the user re-launch our Action by clicking on a link. But we need to enable linking in the Action console and get the URL that they will link to.

  1. In the Actions on Google console, select Actions in the left navigation.

  2. Select the "welcome" Intent.

    Actions list

  3. Scroll down to the "Links" section and expand it by clicking on the header.

  4. Enable a URL by turning on the switch.

  5. Enter a required (but unused) Link title.

  6. You'll see an HTML code snippet underneath. You will be entering just the URL for this code snippet in the configuration later.

    Enabling URL linking

Setup Google Sign In for Assistant

We will use the same configuration we did in the auth1 example.

  1. In the Actions on Google console, you'll select the Account linking left navigation (possibly scrolling to the bottom to get to it).

    Account linking

  2. Expand the Account Creation section and set "Yes, allow users to sign up for new accounts via voice".

    Account Creation

  3. Expand the Linking Type section and make sure that "Google Sign In" is selected.

    Linking type

  4. Expand the Client Information section. You will see a Client ID field with information you'll need to add to your multivocal configuration.

    Client Information

Setup Google Cloud API Library Access

Since our webhook will query information in Google Drive, we will need to get permission for our project to access the Drive API. We will do this through the Google Cloud Console.

  1. Make sure your current project is selected.

  2. Select the "hamburger" icon in the upper left to bring up the menu.

  3. Select the "APIs & Services" menu item and then "Library"

    Cloud console menu

  4. There will be a screen welcoming you to the new API Library. In the "Search for APIs & Services" box, type "drive".

    Search for APIs

  5. The screen will update as you type, leaving you with just a few choices. Select the "Google Drive API" box.

    Select Google Drive

  6. It will confirm the API you've chosen. Select the "Enable" button.

    Enable Google Drive

Setup Google Cloud API Credentials

Since we also need to get credentials for the web client and the Action to access the API, we will setup two OAuth2 credentials.

Both of them should have already been created for us. The web client credentials are created when we create the project, while the Action credentials are created when we turn on Google Sign In for Assistant. We will need the value of the Client ID later, so to view the credentials:

  1. Select the "hamburger" icon in the upper left to bring up the menu.

  2. Select the "APIs & Services" menu item and then "Credentials"

    Cloud console menu

  3. You should see a list of credential types. In the "OAuth 2.0 client IDs" section, there will be a "Client ID" column. There will also be two rows: one for an Actions on Google App, and one for a Web client. You will need these value for the configuration later.

    Client IDs

  4. The web client should be locked down to just the domain that our web page will be running on. During testing, this may be localhost, or an ngrok proxy URL, but in production it will likely be the domain provided by Firebase Hosting.

    To add these as authorized pages, we need to click on the pencil on the Web client row.

    Edit client

  5. We can then add the valid origins, one per line. We do not need to add the Redirect URIs. Once we've added all the origins, we can click Save.

    Add valid origins

Setup Firebase Database

We are using the Firebase Database to store the Multivocal configuration, the web page configuration, and the list of users. Since users should not be allowed to write to any of these nodes, and should only be able to read the web configuration, we need to install some database rules. These are in the dataabse.rules.json file:

  "rules": {
    "web": {
      ".read":  true,
      ".write": false
    "multivocal": {
      ".read":  false,
      ".write": false
    "user": {
      ".read":  false,
      ".write": false

we can load them into Firebase using the following command line:

firebase deploy --only database

Create a Login Web Page

Our user will need to login to our service via the web and grant us permission to access some information in their Google Drive account. Since we will want to do this through an Action without requiring them to login every time, we request "offline access" which will give us both an auth token, which grants us the access we want for a limited time, and a refresh token, which gives us the ability to get new access tokens when the first has expired. We will store these tokens in a Firebase database.


We're going to use a fairly basic HTML file on our website, but won't go over all the details of the page. While you can use this page as a foundation, you'll probably want to dress it up to include things such as your privacy policy (which Google requires).

Before we get to the Javascript, let's skip to the bottom to look at the document body. We include three blocks which will be shown or hidden based on where the user is during the login process.

  <h1>Multivocal Example Auth2</h1>

  <div id="g-signin2" class="g-signin2"></div>
  <div id="working">Working...</div>
  <div id="link-action">You're all set! <a href="">Return to Action</a></div>


The g-signin2 area will contain the button that Google's code will add, while the working and link-action blocks start out hidden, and will be shown at various points in our code.

Speaking of our code - what is it doing, anyway?

We start out by loading JQuery (because it makes a few things a touch easier) and some Firebase functions. We'll also use the automatic Firebase configuration that we can load

    <script src="//"></script>

    <script src="/__/firebase/5.1.0/firebase-app.js"></script>
    <script src="/__/firebase/5.1.0/firebase-database.js"></script>
    <script src="/__/firebase/init.js"></script>

Once these are loaded, the script starts out by loading the configuration from the Firebase database and saving it to use at other points in the script.

      var database = firebase.database();
      var conf;
        var config = snapshot.val();
        conf = config;

        // Set the link to the Action
        $('#link-action a').attr('href',conf.action.uri);

        return config;

Once the configuration has been loaded, it turns some of this configuration into HTML tags. These tags are used to configure the Sign-In button when we load the script from Google - which we do by adding the script tag as well.

        // Turn the sign-in configuration into meta tags
        var signinConfig = conf.signin;
        var keys = Object.keys( signinConfig );
        for( var co=0; co<keys.length; co++ ){
          var name = keys[co];
          var content = signinConfig[name];
          var tag = '<meta name="google-signin-'+name+'" content="'+content+'">';
          console.log( tag );

        // Add the script tag to load the sign-in button
        // When it is loaded, the "start" function will be called
        tag = '<script src="" async defer>';


Once the script loads and displays the button, it calls the start() function.

Our start() function is a little convoluted.We need to remove the normal click handler, which starts to get the user's permission, with our own click handler. That click handler gets the user's permissions that we want, but also gets permission to do offline access, which will allow us to get a refresh token as well.

When the user clicks the button now, it will pop up a window to get permission. Once the user has given permission to access the scopes (and access it offline), the onSignIn() method will be called.

      // Called when the sign-in button has been loaded
      function start(){
        // Remove the existing callback and add our own to initiate a login
        // with offline access
          console.log( 'click' );

          // When clicked, get the auth instance for the user,
          // request offline access, and call the onSignIn() function
          // when they've signed in and granted permission.
          var auth2 = gapi.auth2.getAuthInstance();
            console.log( 'initialized' );
            return auth2.grantOfflineAccess();

The onSignIn() method is called with an object containing information about the user, including the auth code. Once we get this, we hide the sign-in button and show our "working" message. We'll get all this information and send it to the codeExchange URL that we have in our configuration. This is one of the functions we have running in Firebase Cloud functions, and we cover it below. For now, we just needs to know that it gets the auth code from the user configuration, saves it, and then returns a success when it's done. At that point, the onSuccess() function will be called.

      // Once signed in, send the code to the server to exchange for the
      // auth token and refresh token.
      // (We can get a token from the auth instance if we need to do something
      // from the client.)
      function onSignIn( googleUser ) {
        // Hide the button and show that we're still working

        // Send the code to our exchange endpoint
        // When this is done, call onSuccess()
        var url = conf.codeExchange.uri;
          type: 'POST',
          url: url,
          contentType: 'application/json',
          processData: false,
          data: JSON.stringify(googleUser),
          success: onSuccess

Once the code is saved on the server, we're done and ready to return to the Action. We'll hide our "working" message and replace it with a link that will launch the Action again.

      // Once the code exchange has taken place
      function onSuccess( data, status, xhr ){
        // Hide the working button and show a link back to our Action

Once the user clicks the link, they'll be taken back to the Action and our page has served its purpose.

Firebase Database: web configuration

The web page makes use of a Firebase db to get some configuration information. It is important to realize that this information must all be public, so reading it from the configuration from the datastore is fine, but it must be kept separate from the Multivocal configuration, which does contain information that users should not have access to.

Firebase db web hierarchy

The codeExchange.uri setting will be set to the URL for our function that does the code exchange (which we're about to talk about). Once we deploy the function for the first time, we'll see the URL for it.

We need the action.uri setting for the link from the page to start the Action back up again. We can get this from the Actions console as we described in the prerequisites.

For the signin button, we need to set the scope to "profile email openid", enumerating the scopes we need to access their profile and the metadata about their Google Drive files. We also need to set client_id, which we can get from the Google Cloud Console API Credentials page - we should use the OAuth 2.0 Client ID listed for the "Web client" that we made sure was configured as part of the prerequisites.


In one of our steps above, Google sends us some user information, including the auth code. We need to setup a Firebase Cloud Function that will process this. We'll use the same pattern that Multivocal uses and have most of the work done in a file we require

const AuthCode = require('./authCode');

and then just export this to create the function with FCF.

exports.code = AuthCode.exchangeWebhook;

Which we then need to put in another file.


The function that we export that does all the work is pretty straightforward, and we'll break down how most of the parts work. We'll use the same pattern that Multivocal uses - putting everything in an environment, which we need to build first. We'll then call Google's API to convert the auth code into the auth token and refresh token, use the auth token to get some more information about the user, and then store all this in a data store to be used later. Finally, we'll return a message to our web page saying that everything is good (or not).

const FirebaseFunctions = require('firebase-functions');
var exchangeWebhook = FirebaseFunctions.https.onRequest( (request,response) => {
  return buildEnv( request, response )
    .then( env => loadTokens( env ) )
    .then( env => loadUserinfo( env ) )
    .then( env => saveUser( env ) )
    .then( env => returnResult( env ) )
    .catch( err => returnError( response, err ) );

exports.exchangeWebhook = exchangeWebhook;

Building the environment in buildEnv() is pretty straightforward. We're just making an object with the request and response objects, along with the body of the request and the code. We're also loading the configuration that Multivocal has loaded - we might as well take advantage of it for any settings we are making.

var buildEnv = function( request, response ){

  return Multivocal.getConfig()
    .then( config => {
      var env = {
        Config: config,
        Request:  request,
        Response: response,
        Body: request.body,
        code: request.body.code
      return Promise.resolve( env );

Converting the code into tokens requires us to call Google's code exchange endpoint with the code, along with our client ID, client secret, and the redirect URI that we have registered with Google through the Cloud Console above. All of these are stored in our settings (which we discuss later). We'll get back a JSON object that includes token information that we'll save in our environment.

var loadTokens = function( env ){

  var settings = env.Config.Setting.codeExchange;

  var body = {
    code:          env.code,
    client_id:     settings.clientId,
    client_secret: settings.clientSecret,
    redirect_uri:  settings.redirectUri,
    grant_type:    settings.grantType || 'authorization_code'

  var options = {
    method: 'POST',
    uri:    settings.uri,
    form:   body,
    json:   true

  return rp( options )
    .then( tokens => {
      env.tokens = tokens;
      return Promise.resolve( env );

With the auth token, we can get the profile about this user from Google's "userinfo" endpoint. Again, we'll store their profile and id in our environment.

var loadUserinfo = function( env ){
  var settings = env.Config.Setting.userinfo;

  var accessToken = env.tokens['access_token'];

  var options = {
    method: 'GET',
    uri:    settings.uri,
    headers: {
      "Authorization": `Bearer ${accessToken}`
    json: true

  return rp( options )
    .then( profile => {
      env.profile = profile; =;
      return Promise.resolve( env );


We then save this information into the datastore (which we cover in the next section) and send back a JSON response to the user.


The saveUser() function takes the user ID, optionally the tokens, and optionally the profile of the user and saves them in our data store. In this case, we'll use the Firebase database, since we're also using that for other parts of the project.

Mostly, we just put these into an object and update the Firebase db at the path user/ID with this object. This update doesn't clear out anything that isn't set in the update object, so it is safe to include just some parts.

The only real difference is that we supplement the token information. The token info that comes from Google includes a field expires_in, which indicates how many seconds the token is good for. We use this to compute an expires after time which we save.

var saveUser = function( id, tokens, profile ){
  console.log('datastore id',id);
  var dbPath = db.ref('user').child(id);
  var obj = {};
  if( tokens ){
    if( !tokens['expires_after'] ){
      tokens['expires_after'] = + (tokens['expires_in'] * 1000);
    obj.tokens = tokens;
  if( profile ){
    obj.profile = profile;
  return dbPath.update( obj );
exports.saveUser = saveUser;

Write and Configure the Action

This Action is different than our previous two auth examples. Since the purpose is to access a Google resource with an auth token, there are a number of additional tasks we'll need to take as part of the Action itself, but we'll limit what it can do to just saying the answer and quitting.

Because it needs to get the auth, there are two paths it can take:

  1. If we have logged in previously, it uses the ID Token to get the user's records, including their auth token, and uses this to make a call to Google Drive to get the information we want.
  2. If we have not logged in previously, it directs us to the web page to do the login (that we setup above) and we're then directed back to the Action.


We've already had some lines in index.js to handle the web client processing the one-time code, but now we'll add our standard lines to handle the Action webhook. (As typical, most of the work will be done in config.js.)

const Multivocal = require('multivocal');


exports.webhook = Multivocal.processFirebaseWebhook;


Our configuration is a little different than previous auth examples, but follows much of the same structure. As before, we won't be going through all the details, but we will cover most of the components we find here and why we have them in place.

Since all we're doing is returning one value, we'll be doing that as part of our welcome intent. So our welcome intent will have the requirement that User/IsAuthenticated must be set, as we've done before:

  "Intent.welcome": "User/IsAuthenticated"

Although User/IsAuthenticated is set when multivocal gets a valid identity token, we want to use a different method to request it if not present. So we will be creating what we call a "requirement request" function. In this case, it doesn't need to do much - just set an internal name for what we're requesting (we're going to use "website", but it could be anything) and then do other default tasks:

var requestRequirementsWebsite = function( env ){
  return Multivocal.requestDefault( env, 'website' );

We have to register this function as part of our init() function:

  Multivocal.setRequirementRequest( "User/IsAuthenticated", requestRequirementsWebsite );

One of the default tasks is to adjust what the Action, Intent, and Outent environment settings are to reflect that we're requesting something - in this case, we're requesting a "website" (our internal name above). (It also saves this information in a context, so it re-attempts the welcome once we have the information we want.) So we'll be able to set a response configuration under Local/en/Response:

  "": [
      ShouldClose: true,
      Template: {
        Ssml: "Before we begin, I need you to log in on the website.",
        Text: "Before we begin, I need you to log in at {{}}.",
        Option: {
          Type: "Carousel",
          Items: [
              Body: "Log in on the website",
              Url: "{{}}"

This sends a message (the verbal one is slightly different than the one that is displayed) and a card with a link to the website that the user should use to login with.

Once the user has gone through the login on the website, or if they're returning to us after previously authenticating themselves and authoring us to access their Drive, we will have the user ID as part of their profile. In order to get the values we need to give them an answer, we need to do a few things:

  • Get their profile from our database, including their auth token
  • Possibly refresh the token, if it has expired
  • Load the values we want using Google Drive's API And then we can call the default handler which will send the message and close the conversation.

To do all this, we create a handler

var handleFileCount = function( env ){ = env.User.Profile.sub;
  return loadUser( env )
    .then( env => loadTokens( env ) )
    .then( env => loadFileCount( env ) )
    .then( env => Multivocal.handleDefault( env ) );

and register it

  Multivocal.addIntentHandler( "welcome", handleFileCount );

A few important things to note about the handleFileCount() function:

  • As with most functions in multivocal, we treat it as asynchronous so we need to return a Promise that resolves to the environment (which is also passed in).
  • The environment is always passed around and stores everything we want to remember.
  • We break it down into small parts (which we'll look at in a moment).
  • At the end, we call the default handler.

The loadUser() function is a wrapper around our Datastore library that gets the user's profile from the Firebase database from the user's ID:

var Datastore = require('./datastore');

var loadUser = function( env ){
  return Datastore.getUser( )
    .then( user => {
      env.user = user;
      return Promise.resolve( env );

The loadTokens() function looks long, but does two things.

First, if the tokens are valid, it puts all the token info into an environment setting, tokens, and then returns the Promise with the environment.

  var now =;
  if( env.user.tokens.expires_after > now ){
    env.tokens = env.user.tokens;
    return Promise.resolve( env );

If the auth token has expired, however, it needs to contact the code exchange endpoint and use the refresh token to get a new auth token and save all the token information in the datastore again (as well as saving it in the environment) before returning a Promise with the environment.

  var settings = env.Config.Setting.codeExchange;

  var refreshToken = env.user.tokens.refresh_token;

  var body = {
    refresh_token: refreshToken,
    client_id:     settings.clientId,
    client_secret: settings.clientSecret,
    grant_type:    'refresh_token'

  var options = {
    method: 'POST',
    uri:    settings.uri,
    form:   body,
    json:   true

  return rp( options )
    .then( tokens => {
      tokens.refresh_token = refreshToken;
      env.tokens = tokens;
      return Datastore.saveUser(, tokens );
    .then( result => Promise.resolve( env ) );

Finally, the loadFileCount() functions calls the Drive API with the access token. We'll request 100 files (the max allowed), but we don't need much information about each, since we just want the count, which we store in the fileCount environment. If it tells us there are more files - we're not going to get them, we'll just set an environment field called tooManyFiles to indicate we have a lot of them.

  var accessToken = env.tokens.access_token;

  var options = {
    method: 'GET',
    uri: '',
    headers: {
      Authorization: `Bearer ${accessToken}`
    qs: {
      pageSize: 100,
      fields: 'kind,nextPageToken,files/id'
    json: true
  return rp( options )
    .then( result => {
      env.fileCount    = result.files.length;
      env.tooManyFiles = result.nextPageToken ? true : false;
      return Promise.resolve( env );

This is a common pattern - handle logic in code, where it makes sense to, and store the result in the environment. We store everything in the environment, because it makes it a lot easier when we go to send back the results using a template for the welcome intent. That template always sets that we should close the connection after we send the result. If there are too many files, we'll pick from a couple of messages that say so, and if not, we'll send back just one, making sure we use either "file" or "files" as appropriate.

  "Intent.welcome": [
      Base: {Set: true},
      ShouldClose: true

      Base: {Set: true},
      Criteria: "{{tooManyFiles}}"
    "You have too many files for me to count.",
    "You have a lot of files!",

      Base: {Set: true},
      Criteria: "{{not tooManyFiles}}"
    "You have {{inflect fileCount 'file' 'files' true}} in Google Drive"

And, of course, we need to make sure the configuration object is set in multivocal itself. We also make it so configuration can be loaded from the Firebase database:

  new Multivocal.Config.Simple( config );
  new Multivocal.Config.Firebase();

Firebase Database: multivocal configuration

You may have noticed that the configuration setting for the website URL isn't in the config.js file itself. Instead, we include it as part of the Firebase configuration. Unless otherwise configured the Firebase-based configuration uses the structure underneath the multivocal top level entry. In our case, we have everything under the Setting hierarchy, since everything we're putting here is a setting

Firebase db multivocal hierarcy

The Requirements/Auth path contains the same setting that we had in our "auth1" example - the aud string that must match a particular iss domain. However, Firebase db doesn't allow certain characters in a key - particularly the period and forward slash (. and / respecitively), so we have to use an underscore and vertical bar (_ and |) and multivocal's configuration changes them when we read it in. This aud string comes from the Client ID we get from setting up Account Linking in the Actions console. (If you're observant, you'll also note that on the Cloud Console Credentials page, this same Client ID is for the credentials named "New Actions on Google App".)

We use the codeExchange portion of the setting to contain information that is used when we exchange a refresh token for a fresh auth token. This includes the client ID and client secret that are associated with the Web Client, which you can again find on the Cloud Console Credentials page. The redirectUri and uri settings are pretty standard, but we include them as settings in case we need to change them in the future.

The uri for userinfo is the same - this is a pretty standard URL, but we'll make it configurable just in case.

Finally, the website needs to be our own website - we use this in the template we have in config.js to direct users to log in on the website.

Trying it out

Once we've deployed the code, and possibly activated a test through the simulator, we can test it out on our phone. (You can try testing it out on a speaker, but it will just ask you to visit the website without giving you much additional information. A better version of this might make sure we have a mobile device and redirect us to that device.)

Starting the Action

Since we don't have the account linked yet, it prompts us to visit the website and provides a direct link there. If we click on that "Visit" prompt...

Prompted to Sign In

We'll get the page on our website, including the button that is prompting us to sign in. Which we do...


We're greeted with this stern warning that our app hasn't been verified yet, which it hasn't. As we go to production, we'll need to have Google verify that we're legitimate and not trying to pretend to be Google, trying to trick our uses. We will click on the "Show Advanced" link which gives us a link at the bottom to "Go to" our app. We'll click this, keeping in mind that we should get our app verified so we don't see this screen in the future.

Permission screen

Google will then ask the user if our app has permission to access the information described. Hopefully, the user will touch the Allow button.

Back to our website

Which will bring us back to our website. Behind the scenes, the page will receive a one-time code, and will send this to the server, which does the work of getting the tokens we need, getting our profile, and all the stuff we discussed above. Once everything is good, we'll get a link back to the Action.

Restarting the Action

The Action will automatically start from the link, get the information we've permitted it to, and tell us how many files there are (or if there are too many to count).

Future times that we start the action will also just work. Unless the user revokes our permission, we won't have to go through this process again.


Demonstrating how to do authentication and authorization with Actions on Google, Google Sign In, and multivocal







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