Google Firebase Account Service generate Token Server with Node.js

app.js

var { google } = require('googleapis')
var SCOPES = ["https://www.googleapis.com/auth/firebase.messaging"]

var http = require('http')

function getAccessToken() {
    return new Promise(function (resolve, reject) {
        const key = require('./service-account.json');
        const jwtClient = new google.auth.JWT(
            key.client_email,
            null,
            key.private_key,
            SCOPES,
            null
        );
        jwtClient.authorize(function (err, tokens) {
            if (err) {
                reject(err);
                return;
            }
            resolve(tokens.access_token);
        });
    });
}

getAccessToken().then(function(access_token){
    console.log(access_token)
})