example.js

'use strict';

const { createBackgroundTransaction, endTransaction } = require('newrelic');
const fs = require('fs');

createBackgroundTransaction('fileProcessing', () => {
  return new Promise((resolve, reject) => fs.readFile('/tmp/input.txt', (err, file) => {
    if (err) {
      return reject(err);
    }
    resolve(file);
  }))
    .then(file => {
      // process file contents
    })
    .then(() => endTransaction())
    .catch(() => endTransaction());
});