Passing cookies from browser to Guzzle 6 client

Try something like:

/**
 * First parameter is for cookie "strictness"
 */
$cookieJar = new \GuzzleHttp\Cookie\CookieJar(true);
/**
  * Read in our cookies. In this case, they are coming from a
  * PSR7 compliant ServerRequestInterface such as Slim3
  */
$cookies = $request->getCookieParams();
/**
  * Now loop through the cookies adding them to the jar
  */
 foreach ($cookies as $cookie) {
           $newCookie =\GuzzleHttp\Cookie\SetCookie::fromString($cookie);
           /**
             * You can also do things such as $newCookie->setSecure(false);
            */
           $cookieJar->setCookie($newCookie);
 }
/**
 * Create a PSR7 guzzle request
 */
$guzzleRequest = new \GuzzleHttp\Psr7\Request(
                   $request->getMethod(), $url, $headers, $body
        );
 /**
  * Now actually prepare Guzzle - here's where we hand over the
  * delicious cookies!
  */
 $client = new \GuzzleHttp\Client(['cookies'=>$cookieJar]);
 /**
  * Now get the response
  */
 $guzzleResponse = $client->send($guzzleRequest, ['timeout' => 5]);

and here's how to get them out again:

$newCookies = $guzzleResponse->getHeader('set-cookie');

I think you can simplify this now with CookieJar::fromArray:

use GuzzleHttp\Cookie\CookieJar;
use GuzzleHttp\Client;

// grab the cookies from the existing user's session and create a CookieJar instance
$cookies = CookieJar::fromArray([
     'key' => $_COOKIE['value']
], 'your-domain.com');
// create your new Guzzle client that includes said cookies
$client = new Client(['cookies' => $jar]);