Apigee JS httpClient with retry

getTokenWithRetry.js

// getTokenWithRetry.js
// ------------------------------------------------------------------
//
// Example JS policy configuration:
//
// Note: you need the authUrl Property.
//
// <Javascript name='JS-Retrieve-Token' timeLimit='12000' >
//   <Properties>
//     <Property name='authUrl'>https://url-for-token-endpoint/token</Property>
//   </Properties>
//   <ResourceURL>jsc://getTokenWithRetry.js</ResourceURL>
// </Javascript>
//

/* jshint esversion:6, node:false, strict:implied */
/* global print, context, properties, httpClient, Request */

var MAX_CYCLES = 3;
var cycleCount = 0;

// fill the following with what you need
var headers = {};
var payload = "";

/*
 * The callback invoked after an httpClient call completes.
 * If the call was not successful, conditionally retry.
 * If successful or if retry limit has been reached, set a context variable and return.
 *
 */
function onComplete(response, error) {
  cycleCount++;
  if (error || response.status != 200) {
    // error => no response, call failed.  Maybe a network error?
    // status!= 200 => response, but not successful.
    if (cycleCount < MAX_CYCLES) {
      sendOne();
      return;
    }
  }
  // If reaching here, either the call was successful, or we reached the limit
  // of retries after error. Either way, set variables and terminate the chain.
  context.setVariable("token-response-tries", cycleCount.toFixed(0));
  if (response.content) {
    context.setVariable("token-response-content", response.content);
  }
  return;
}

function sendOne() {
  var req = new Request(String(properties.authUrl), "POST", headers, payload);
  httpClient.send(req, onComplete);
}

sendOne();