Proper reconnection to RabbitMQ

[alteest]

There is a problem with connection when it closed on remote side.
To solve such issue was implemented code like this (but it help not in all cases):

                try:
                     ....
                except aiormq.exceptions.ChannelInvalidStateError:

                    if broker._channel:
                        await broker._channel.reopen()

But it does not work, here is an exception:

  ...
  File "/usr/local/lib/python3.12/site-packages/faststream/rabbit/publisher/usecase.py", line 288, in publish
    return await call(message, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/faststream/broker/middlewares/base.py", line 115, in publish_scope
    await self.after_publish(err)
  File "/usr/local/lib/python3.12/site-packages/faststream/broker/middlewares/base.py", line 90, in after_publish
    raise err
  File "/usr/local/lib/python3.12/site-packages/faststream/broker/middlewares/base.py", line 102, in publish_scope
    result = await call_next(
             ^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/faststream/rabbit/publisher/producer.py", line 102, in publish
    r = await self._publish(
        ^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/faststream/rabbit/publisher/producer.py", line 235, in _publish
    return await exchange_obj.publish(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/aio_pika/exchange.py", line 194, in publish
    raise aiormq.exceptions.ChannelInvalidStateError(
aiormq.exceptions.ChannelInvalidStateError: <aio_pika.robust_channel.RobustChannel object at 0x7f6ea5433f80> closed

During handling of the above exception, another exception occurred:

  File "...", line 145, in test.py
    await broker._channel.reopen()
  File "/usr/local/lib/python3.12/site-packages/aio_pika/robust_channel.py", line 132, in reopen
    await super().reopen()
  File "/usr/local/lib/python3.12/site-packages/aio_pika/channel.py", line 244, in reopen
    await self._open()
  File "/usr/local/lib/python3.12/site-packages/aio_pika/channel.py", line 173, in _open
    channel = await UnderlayChannel.create(
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/aio_pika/abc.py", line 485, in create
    channel = await connection.channel(**kwargs)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/aiormq/connection.py", line 830, in channel
    raise RuntimeError("%r closed" % self)
RuntimeError: <Connection: "amqps://..." at 0x7f6e59f476b0> closed

Restart helps, but how properly reconnect to broker without restart?

[Lancetnik]

RabbitBroker reconnects to remote host automatically when it becomes available. You can just wait for this moment

[alteest]

Not in all cases. When queue delete on remote side (during maintenance) and in some other cases, RabbitBroker don't reconnect at tries to use old chaneel object wich is disconnected and only retart helps

[Lancetnik]

Sorry, I can't image a good API for such specific cases. Moreover, I don't think, that code should solve an infrastructure problems

[alteest]

The solution can be just a method like 'reconnect' which will do reconnection from scratch without usage already created channels, conenctions, etc

[Lancetnik]

So, you can just call close & start again – there is no problem

[alteest]

I tried it and broker still use some already closed channels