[Messenger][AMQP] Use delivery_mode=2 by default

[lyrixx]

Q	A
Branch?	master
Bug fix?	no
New feature?	no
Deprecations?	no
Tickets	Fix #34685
License	MIT
Doc PR

[lyrixx]

I have tested it:

<?php

use Symfony\Component\Messenger\Transport\AmqpExt\AmqpStamp;
use Symfony\Component\Messenger\Transport\AmqpExt\Connection;

require __DIR__.'/vendor/autoload.php';

$connection = Connection::fromDsn('amqp://rabbitmq-3.lxd?exchange[name]=test');
$connection->publish('body', [], 0, new AmqpStamp('test'));

I have created an exchange (fanout) and a queue by hand.

---

This is not related, but I notice something strange: The component created the a queue messages for me :/ Why? Where does "messages" comes? I know it's the default exchange name but in my case, I forced the exchange name to test and my routing key was test. More over the exchange was in a fanout mode, so IMHO it does really make sens here to create the queue since a queue is already bound. Is there a way to avoid that?

OK, I tried

$connection = Connection::fromDsn('amqp://rabbitmq-3.lxd?exchange[name]=test&queues[test]=&queues[test2]=');
$connection->publish('body', [], 0, new AmqpStamp('test'));

And it does what I want 👍

So now I have another question: If I want to publish to 2 different exchanges, I have to create 2 connection?

[pyrech]

Shouldn't this PR be considered as a bug fix? If not, that means that Symfony 4.4 & 5.0 will provide an AMQP connection that is not safe to use by default.

[lyrixx]

I agree with @pyrech here.

To be really clear : Right now if you restart rabbitmq, you will loose all messages. This is really not safe.

@fabpot Are you OK to treat this PR as a bug fix ?

[nicolas-grekas]

As bug fix on 4.4/4.3 as it fits.

[lyrixx]

I updated the PR to target 4.3

[fabpot]

Thank you @lyrixx.

[weaverryan]

About the “messages” queue being created, you could create a separate issue for that. There is a queues config option and I think you could set it to an empty array to avoid this (but I could be wrong). In general, there are many different ways for using Amqp - and so we need to make it work as smoothly as possible for as many cases as we can.

[Tobion]

Seems fine to do this by default as many people don't know the default settings of AMQP it seems. But it will make the AMQP way slower. I used a transport decorator for this so far when I needed it.

/**
 * Decorates a transport and makes all messages getting sent persistent.
 */
class PersistentMessagesTransportDecorator implements TransportInterface, SetupableTransportInterface
{
    private const DELIVERY_MODE_PERSISTENT = 2;

    /**
     * @var TransportInterface
     */
    private $decoratedTransport;

    public function __construct(TransportInterface $decoratedTransport)
    {
        $this->decoratedTransport = $decoratedTransport;
    }

    public function setup(): void
    {
        if ($this->decoratedTransport instanceof SetupableTransportInterface) {
            $this->decoratedTransport->setup();
        }
    }

    public function get(): iterable
    {
        return $this->decoratedTransport->get();
    }

    public function ack(Envelope $envelope): void
    {
        $this->decoratedTransport->ack($envelope);
    }

    public function reject(Envelope $envelope): void
    {
        $this->decoratedTransport->reject($envelope);
    }

    public function send(Envelope $envelope): Envelope
    {
        return $this->decoratedTransport->send($this->addPersistentDeliveryModeToEnvelope($envelope));
    }

    private function addPersistentDeliveryModeToEnvelope(Envelope $envelope): Envelope
    {
        /** @var AmqpStamp|null $amqpStamp */
        $amqpStamp = $envelope->last(AmqpStamp::class);
        $attributes = $amqpStamp ? $amqpStamp->getAttributes() : [];
        $attributes['delivery_mode'] = self::DELIVERY_MODE_PERSISTENT;

        $amqpStampWithDeliveryMode = new AmqpStamp(
            $amqpStamp ? $amqpStamp->getRoutingKey() : null,
            $amqpStamp ? $amqpStamp->getFlags() : \AMQP_NOPARAM,
            $attributes
        );

        return $envelope->with($amqpStampWithDeliveryMode);
    }
}