Is it possible to do google API sign in from the server side and pass the result to user?

Question

I have an app that clients can pick a time to book a video appointment and I just want to send them the Google Hangouts Meet link. For this purpose I'm using google calendar API in my JavaScript code from this document https://developers.google.com/calendar/create-events it works and I can create the link fine. But my question is that is there any way that I can create the link based on the time that they select on server side (node js) with a Gsuite account and just send them the link at the end? (I don't want to create event on their Google calendar or send them notification from Google) I don't want the user to prompt with Google login page for authorization. I just need to create the link and send it to the client.Is this possible? I appreciate any suggestion.

Answer 1

Using the code from this guide to auhtenticate with a service account and searching in this examples from the google-auth nodejs repository to see how to set the subject parameter which is the used to impersonate a user, I was able to get the authenticated JWT auth client object which can be used to make google API requests like listing the events of the impersonated user:

let google = require('googleapis').google;
let privatekey = require("./[JSON-FILENAME].json");

// configure a JWT auth client
let jwtClient = new google.auth.JWT(
    privatekey.client_email,
    null,
    privatekey.private_key,
    ['https://www.googleapis.com/auth/calendar'],
    '[EMAIL-OF-USER-TO-IMPERSONATE]'
);
//authenticate request
jwtClient.authorize(function (err, tokens) {
    if (err) {
        console.log(err);
        return;
    } else {
        console.log("Successfully connected!");
    }
});

listEvents(jwtClient);

function listEvents(auth) {
    const calendar = google.calendar({ version: 'v3', auth });
    calendar.events.list({
        calendarId: 'primary',
        timeMin: (new Date()).toISOString(),
        maxResults: 10,
        singleEvents: true,
        orderBy: 'startTime',
    }, (err, res) => {
        if (err) return console.log('The API returned an error: ' + err);
        const events = res.data.items;
        if (events.length) {
            console.log('Upcoming 10 events:');
            events.map((event, i) => {
                const start = event.start.dateTime || event.start.date;
                console.log(`${start} - ${event.summary}`);
            });
        } else {
            console.log('No upcoming events found.');
        }
    });
}