Guzzle 6 retry middleware

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Recently I switched from using Guzzle 5 to Guzzle 6 in my mediawiki-api-base PHP library. Everything went very smoothly except for there being no compatible version of the retry-subscriber that I had previously used. The subscriber has been replaced by retry middleware of which I was provided an extracted example. In this post I cover my implementation for the mediawiki-api-base library.

Guzzle 5

With Guzzle 5 you would create a retry subscriber with a filter and then attach it to the event emitter for the guzzle client. A full example can be seen below where RetrySubscriber::createStatusFilter can be seen here.

// Retry 500 and 503 responses
$retry = new RetrySubscriber([
    'filter' => RetrySubscriber::createStatusFilter(),
    'delay'  => function ($number, $event) { return 1; },
    'max' => 3,
]);

$client = new GuzzleHttp\Client();
$client->getEmitter()->attach($retry);

Guzzle 6

Guzzle 6 got rid of its event system and switched to the afore mentioned middleware system.

Middleware is added to a handler stack upon Client construction as seen below:

$handlerStack = HandlerStack::create( new CurlHandler() );
$handlerStack->push( Middleware::retry( retryDecider(), retryDelay() ) );
$client = new Client( array( 'handler' => $handlerStack ) );

The retry middleware takes two parameters, the first is the callable function that decides if a request / response should be retried and the last deciding how long to wait before retrying (similar to in Guzzle 6). Each can be seen below.

function retryDecider() {
   return function (
      $retries,
      Request $request,
      Response $response = null,
      RequestException $exception = null
   ) {
      // Limit the number of retries to 5
      if ( $retries >= 5 ) {
         return false;
      }

      // Retry connection exceptions
      if( $exception instanceof ConnectException ) {
         return true;
      }

      if( $response ) {
         // Retry on server errors
         if( $response->getStatusCode() >= 500 ) {
            return true;
         }
      }

      return false;
   };
}
function retryDelay() {
    return function( $numberOfRetries ) {
        return 1000 * $numberOfRetries;
    };
}

When implementing this for the mediawiki-api-base library I actually ended up creating a MiddlewareFactory which can be seen at on github here which is fully tested here.

This implementation includes a more complex retry decider including logging.

Enjoy!

15 thoughts on “Guzzle 6 retry middleware”

  1. is there a provision of setting timeout with guzzle retry middleware? I want the retry attempt to be made upon expiration of pre-defined timeout interval

    Reply

  3. I’m curious, is this where OAuth token refreshes would be performed, or is that something which would have to be down further back up the chain?

    Reply

    • I have not really worked with OAuth & Guzzle yet so can’t give you the ‘right’ answer. It definitely sounds possible though.

      Reply
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  5. I’ve been following your example & making multiple asynchronous requests with Promise/any() functions.
    When retry middleware is not used & some of the api end-points are down, this is working fine. But when adding retry middleware while some end-points are down, the request gets slow. It seems that, though other end-points are up, but the failing points are blocking and retrying.

    trait RetriesRequest {

public function getRetryHandler()
{
    $handlerStack = HandlerStack::create(new CurlHandler());

    $handlerStack->push(Middleware::retry($this->retryDecider(), $this->retryDelay()));

    return $handlerStack;

}

public function retryDecider()
{

    return function (
        $retries,
        Request $request,
        Response $response = null,
        RequestException $exception = null
    ) 

    {


        // Limit the number of retries to 5
        if ($retries >= 5)
        {

            return false;

        }


        // Retry connection exceptions
        if ($exception instanceof ConnectException)
        {

            return true;

        }


        if($exception instanceof AggregateException)
        {

            return true;

        }


        if ($response)
        {
            // Retry on server errors
            if ($response->getStatusCode() >= 500 )
            {

                return true;

            }

        }

        return false;
    };

}



/**
 * delay 1s 2s 3s 4s 5s
 *
 * @return Closure
 */

public function retryDelay()
{

    return function ($numberOfRetries) 
    {
        return 2000;
        // return 1000 * $numberOfRetries;
    };

}

    }

    Request Call Code:
    trait SearchesFlights
    {

    use ParsesJason, RetriesRequest;

private $endPoints = [
                'v1'=> '127.0.0.1:5354', //post request,  body.date
                'v2' => '127.0.0.1:5939', //post request,  body.date
                'v3' => '127.0.0.1:4949', //post request,  body.date
                'v4' => '127.0.0.1:5051', //get request, no body
                'v5' => '127.0.0.1:5052', //get request, no body
            ];



private $postDate = '02/04/2018';


public function searchByDate()
{

    $client = new Client(array('handler' => $this->getRetryHandler()));

    /* $client = new Client();*/

        $promises = $this->getPromiseArray($client);

    $promise = Promise\any($promises)->then(

        function (PsrResponse $response){


            return $this->getAll(json_decode($response->getBody()));


        },

        function ($reason) {

            return $reason;

        }

    );

    $result = $promise->wait();

    return $result;

}




/*Returns Promise Array with post requests*/

private function getPromiseArray($client)
{

    $options = ['form_params' => ['date' => $this->postDate]];

    return $promises = [
        'server1' => $client->requestAsync('POST', $this->endPoints['v1']),
        'server2' => $client->requestAsync('POST', $this->endPoints['v2']),
        'server3' => $client->requestAsync('POST', $this->endPoints['v3'], $options),


    ];


}


}
    Reply

  6. Should Line 20 be \GuzzleHttp\Exception\ConnectException?
    I am getting following error.
    Argument 4 passed to guzzelRetryClient::{closure}() must be an instance of GuzzleHttp\Psr7\RequestException, instance of GuzzleHttp\Exception\ConnectException given

    Reply
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