trying to work through a kong hmac implementation

hmac-test.js

const crypto = require( 'crypto' );
const hostname = 'localhost';
const proxyPort = '8000';
const http = require( 'http' );
const requestPath = '/v1.0/recognition/public-wall';

const hmacHeaders = ( username, secret ) => {
  const date = new Date().toUTCString();
  const stringToSign = 'date: ' + date;
  const encodedSignature = crypto.createHmac( 'sha1', secret ).update( stringToSign ).digest( 'base64' );
  const hmacAuth = 'hmac username="' + username + '",algorithm="hmac-sha1",headers="date",signature="' + encodedSignature + '"';

  const headers = {
    'date': date,
    'Authorization': hmacAuth
  };

  return headers;
};

const headers = hmacHeaders( 'bob', 'secret456' );

const options = {
  host: hostname,
  port: proxyPort,
  path: requestPath,
  method: 'GET',
  headers: {
    'Content-Type': 'application/json',
    'date': headers.date,
    'Authorization': headers.Authorization
  }
};

const req = http.request( options, function( res ) {
  console.log( res.statusCode );
  res.setEncoding( 'utf8' );
  res.on( 'data', function( d ) {
    console.log( d );
  } );
} );

req.end();