Alert using SMS on file creation

file-sms-signal.js

var path = require('path');
var {poll} = require('@nkashy1/pollster');
var {spawnPredicate} = require('@nkashy1/pollster/predicates');
var twilio = require('twilio');

// START fs config
var rawFilepath = process.env.WATCH_FILE;
if (!rawFilepath) {
    throw new Error('WATCH_FILE (undefined) should be the path that you want to poll for file existence');
}
var filepath = path.normalize(rawFilepath);
// END fs config

// START twilio config
var twilioAccountSid = process.env.TWILIO_ACCOUNT_SID;
var twilioAuthToken = process.env.TWILIO_AUTH_TOKEN;
var twilioPhoneNumber = process.env.TWILIO_PHONE_NUMBER;
var notificationPhoneNumber = process.env.NOTIFICATION_PHONE_NUMBER;

if (!twilioAccountSid || !twilioAuthToken || !twilioPhoneNumber || !notificationPhoneNumber) {
    let message = (
            'The following environment variables should be defined:\n' +
            `TWILIO_ACCOUNT_SID: ${!!twilioAccountSid}\n` +
            `TWILIO_AUTH_TOKEN: ${!!twilioAuthToken}\n` +
            `TWILIO_PHONE_NUMBER: ${!!twilioPhoneNumber}` +
            `NOTIFICATION_PHONE_NUMBER: ${notificationPhoneNumber}`
            );
    throw new Error(message);
}

var twilioClient = new twilio(twilioAccountSid, twilioAuthToken);
// END twilio config

function smsSignaller(twilioClient, twilioPhoneNumber, notificationPhoneNumber, message) {
    function sendSignal(err) {
        if (!!err) {
            console.error(err);
            process.exit(1);
        }

        return twilioClient.messages.create({
            body: message,
            to: notificationPhoneNumber,
            from: twilioPhoneNumber
        }, function(err, message) {
            if (!!err) {
                console.error(err);
                process.exit(1);
            }
            console.log(
                    `Message sent: ${message.sid}`);
            process.exit(0);
        });
    }

    return sendSignal;
}

console.log(`Watching for file at ${filepath}...`);
poll(
        spawnPredicate(
            'cat',
            [filepath],
            {},
            100),
        1000,
        Infinity,
        smsSignaller(
            twilioClient,
            twilioPhoneNumber,
            notificationPhoneNumber,
            `File created: ${filepath}`)
    );

package.json

{
  "name": "@nkashy1/file-sms-signaller",
  "version": "0.0.1",
  "description": "Send an SMS on file creation",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "nkashy1",
  "license": "Apache-2.0",
  "dependencies": {
    "@nkashy1/pollster": "0.0.2",
    "twilio": "^3.15.1"
  }
}