Salesforce Login Page not coming for OAuth using NodeJS - node.js

Question

I'm trying to login to Salesforce from Google Assistant (using dialogflow) using OAuth. Whatever I say to Google Assistant is supposed to be fulfilled (matched to intent which is then gets matched to the code that fulfills the intent of the user. So, basically the fulfillment code resides on a server (node js express) hosted on Heroku.
The problem is whenever I start by saying 'Talk to test app' I expect to see the Salesforce login page coming up (where I would enter the creds and then the consent part comes) but this page never comes. I'm sure that there might be something missing on my configuration of account linking / code but i'm not able to understand it.
const express = require('express');
const bodyParser = require('body-parser');
const jsforce = require('jsforce');
const { dialogflow } = require('actions-on-google');
const {
SimpleResponse,
BasicCard,
Image,
Suggestions,
Button
} = require('actions-on-google');
var options;
var port = process.env.PORT || 3000;
const expApp = express().use(bodyParser.json());
//app instance
const app = dialogflow({
debug: true
});
app.intent('Default Welcome Intent', (conv) => {
expApp.get('/oauth2/auth', function(req, res) {
const oauth2 = new jsforce.OAuth2({
clientId: process.env.SALESFORCE_CONSUMER_KEY,
clientSecret: process.env.SALESFORCE_CONSUMER_SECRET,
redirectUri: process.env.REDIRECT_URI
});
res.redirect(oauth2.getAuthorizationUrl({}));
});
//
// Pass received authorization code and get access token
//
expApp.get('/getAccessToken', function(req,res) {
const oauth2 = new jsforce.OAuth2({
clientId: process.env.SALESFORCE_CONSUMER_KEY,
clientSecret: process.env.SALESFORCE_CONSUMER_SECRET,
redirectUri: process.env.REDIRECT_URI
});
const conn = new jsforce.Connection({ oauth2 : oauth2 });
conn.authorize(req.query.code, function(err, userInfo) {
if (err) {
return console.error(err);
}
const conn2 = new jsforce.Connection({
instanceUrl : conn.instanceUrl,
accessToken : conn.accessToken
});
conn2.identity(function(err, res) {
if (err) { return console.error(err); }
console.log("user ID: " + res.user_id);
console.log("organization ID: " + res.organization_id);
console.log("username: " + res.username);
console.log("display name: " + res.display_name);
options = { Authorization: 'Bearer '+conn.accessToken};
});
});
});
conv.ask(new SimpleResponse({
speech:'Hi, how is it going? You are being guided to the login page',
text:'Hi, how is it going? You are being guided to the login page',
}));
});
expApp.get('/', function (req, res) {
res.send('Hello World!');
});
expApp.listen(port, function () {
expApp.post('/fulfillment', app);
console.log('Example app listening on port !');
});

Answer 1

OAuth with Google Assistant is managed from the Actions on Google project that you create for your assistant. In these settings you manage which Token and OAuth URL have to be used for the sign-in in your app. If you want the users to sign-in through the assistant app, you will have to choose the OAuth sign-in option.
So you don't have to use your own code to get the OAuth page, you can just use the SignIn() response given to you in the Actions on Google SDK. This will trigger the account linking flow for Google Assistant.
app.intent('Start Signin', (conv) => {
conv.ask(new SignIn('To get your account details'));
});
app.intent('ask_for_sign_in_confirmation', (conv, params, signin) => {
if (signin.status !== 'OK') {
return conv.ask('You need to sign in before using the app.');
}
// const access = conv.user.access.token;
// possibly do something with access token
return conv.ask('Great! Thanks for signing in.');
});