Gatekeeper Webhook Challenge Response in NodeJS (on PipeDream)

gatekeeper-webhook-nodejs.js

// https://www.gatekeeperhq.com/
// The Vendor & Contract Lifecycle Management (VCLM) Platform
// Webhook 'documentation' on Settings page is for Ruby, incomplete and does not include that the crc_response is to be base64 encoded.
// Video on Knowledgebase contains Python script which shows this is the case:
// https://knowledge.gatekeeperhq.com/en/docs/webhooks

import * as crypto from "crypto";

export default defineComponent({
  async run({ steps, $ }) {
    let response;
    if (steps.trigger.event.method == 'GET' 
        && steps.trigger.event.query.crc_token) {
      let crc_token = steps.trigger.event.query.crc_token
      let secure_token = 'b36f3eef78bcb91e28342a8e875dbf4d1bdbea1462167934'; // Webhook Secure Token
      let algorithm = 'sha256';

      let hmac = crypto.createHmac(algorithm, secure_token);
      hmac.write(crc_token);
      hmac.end();

      let crc_response = Buffer.from(hmac.read('binary')).toString('base64');

      response = {
        status: 200,
        headers: {},
        body: JSON.stringify({crc_response: crc_response }),
      }
    } else {
      response = {
        status: 200,
        headers: {},
        body: '',
      }
    }
    await $.respond(response);
  },
})