Walmart API authentication in Node

api.js

import { createSign, randomBytes } from 'crypto'
import axios from 'axios'
import { resolve } from 'url'

const PK_HEADER = '\n-----BEGIN PRIVATE KEY-----\n'
const PK_FOOTER = '\n-----END PRIVATE KEY-----\n'

const BASE_URL = 'https://marketplace.walmartapis.com/'

const WALMART_CONSUMER =  "b68d2a72....";
const WALMART_SECRET = "MIICeAIBADANBgkqhkiG9w0BAQEFAA......"
const WALMART_CHANNEL = '0f7274e4-0514-4346-b39d-af100936d'

function generateCorrelationId () {
  return randomBytes(16).toString('hex')
}

function generateSignature (url, method, timestamp) {
  const privateKey = `${PK_HEADER}${WALMART_SECRET}${PK_FOOTER}`

  const stringToSign = WALMART_CONSUMER + '\n' +
                     url + '\n' +
                     method.toUpperCase() + '\n' +
                     timestamp + '\n'

  const sign = createSign('RSA-SHA256')

  sign.update(stringToSign)
  return sign.sign(privateKey, 'base64')
}

export function doRequest (endpoint, method) {
  const url = resolve(BASE_URL, endpoint)

  const timestamp = Date.now()
  const signature = generateSignature(url, method, timestamp)

  const headers = {
    'WM_SVC.NAME': 'Walmart Marketplace',
    'WM_CONSUMER.ID': config.walmart.consumer,
    'WM_SEC.TIMESTAMP': timestamp,
    'WM_SEC.AUTH_SIGNATURE': signature,
    'WM_QOS.CORRELATION_ID': generateCorrelationId(),
    'WM_CONSUMER.CHANNEL.TYPE': WALMART_CHANNEL
  }

  return axios({
    method: method,
    url: url,
    timeout: 1000,
    headers: headers
  })
}

index.js

import { doRequest } from 'api'

doRequest('/v2/feeds', 'get')
  .then(function (response) {
    console.log(response)
  })
  .catch(function (error) {
    console.log(error)
  })