Invalid exchange type closes the whole connection, not just the channel

[carlhoerberg]

Declaring an exchange with an invalid exchange type will close the whole connection (COMMAND_INVALID) instead of just the channel, why is that? I would expect a normal channel close (PRECONDITION_ERROR).

require "bunny"
conn = Bunny.new("amqp://localhost").start
conn.channel.exchange_declare("exchange-name", "invalid-exchange-type")

output:

W, [2021-09-07T22:38:46.183689 #2725061]  WARN -- #<Bunny::Session:0x460 guest@localhost:5672, vhost=/, addresses=[localhost:5672]>: Recovering from connection.close (COMMAND_INVALID - unknown exchange type 'invalid-exchange-type')
W, [2021-09-07T22:38:46.184104 #2725061]  WARN -- #<Bunny::Session:0x460 guest@localhost:5672, vhost=/, addresses=[localhost:5672]>: Will recover from a network failure (no retry limit)...
W, [2021-09-07T22:38:56.185432 #2725061]  WARN -- #<Bunny::Session:0x460 guest@localhost:5672, vhost=/, addresses=[localhost:5672]>: Retrying connection on next host in line: localhost:5672
/home/carl/.rbenv/versions/3.0.2/lib/ruby/gems/3.0.0/gems/bunny-2.19.0/lib/bunny/concurrent/continuation_queue.rb:39:in `block in poll': Timeout::Error (Timeout::Error)
        from /home/carl/.rbenv/versions/3.0.2/lib/ruby/gems/3.0.0/gems/bunny-2.19.0/lib/bunny/concurrent/continuation_queue.rb:30:in `synchronize'
        from /home/carl/.rbenv/versions/3.0.2/lib/ruby/gems/3.0.0/gems/bunny-2.19.0/lib/bunny/concurrent/continuation_queue.rb:30:in `poll'
        from /home/carl/.rbenv/versions/3.0.2/lib/ruby/gems/3.0.0/gems/bunny-2.19.0/lib/bunny/channel.rb:1820:in `wait_on_continuations'
        from /home/carl/.rbenv/versions/3.0.2/lib/ruby/gems/3.0.0/gems/bunny-2.19.0/lib/bunny/channel.rb:1191:in `block in exchange_declare'
        from /home/carl/.rbenv/versions/3.0.2/lib/ruby/3.0.0/timeout.rb:97:in `block in timeout'
        from /home/carl/.rbenv/versions/3.0.2/lib/ruby/3.0.0/timeout.rb:107:in `timeout'
        from /home/carl/.rbenv/versions/3.0.2/lib/ruby/gems/3.0.0/gems/bunny-2.19.0/lib/bunny/channel.rb:1616:in `with_continuation_timeout'
        from /home/carl/.rbenv/versions/3.0.2/lib/ruby/gems/3.0.0/gems/bunny-2.19.0/lib/bunny/channel.rb:1190:in `exchange_declare'
        from invalid_exchange_type.rb:3:in `<main>'

[binarin]

I'm looking at https://www.rabbitmq.com/amqp-0-9-1-reference.html#exchange.declare.type, an command-invalid is explicitly mentioned there - "The client MUST NOT attempt to declare an exchange with a type that the server does not support. Error code: command-invalid"

[carlhoerberg]

You're right! Very odd though. Users can easily have forgot to enabled say the consistent hash exchange plugin when setting up a new broker for an existing application. No more "wrong" in that than say publish no an non existing exchange, double ack, or consume from an exclusive queue, that generate channel errors.