[rabbitmq-discuss] configuring an header exchange binding in rabbitmq.cfg

Hi Tom,
Which version of RabbitMQ are you using? "rabbitmq.cfg" isn't a file
name that I recognise - I think you mean "rabbitmq.config", and indeed
that's the file name that the shovel README talks about:
http://hg.rabbitmq.com/rabbitmq-shovel/file/b9f4e6dc4fa3/README

The bind will look something like:

{'queue.bind',
[{exchange, <<"my_exchange">>},
{queue, <<"my_queue">>},
{arguments, [{"x-match", longstr, "any"},
{"headerName", longstr, "headerValue"},
{"otherHeaderName", longstr, "otherHeaderValue"}]}]}

I think.

Matthew

Hi Tom,
That will work if the binding is being created on an endpoint which is
not a "direct" connection. Otherwise, you need to ensure the keys and
values are binaries. There is a bug open for this - it's a mistake in
the erlang client which the shovel uses, but alas it's not been fixed
yet. So if in doubt, use something like:

{'queue.bind',
[{exchange, <<"my_exchange">>},
{queue, <<"my_queue">>},
{arguments, [{<<"x-match">>, longstr, <<"any">>},
{<<"headerName">>, longstr, <<"headerValue">>},
{<<"otherHeaderName">>, longstr, <<"otherHeaderValue">>}]}]}


Matthew

Thanks to Matt for the help; I was able to get a queue binding configured per his advice. Now I'd like to configure an exchange binding, which sadly is not working like I'd hoped. Here's what I have:

{'exchange.declare', [{exchange, <<"events_forwarding_exchange">>}, {type, <<"headers">>}, durable]},
{'exchange.declare', [{exchange, <<"events_local_exchange">>}, {type, <<"topic">>}, durable]},
{'queue.declare', [{queue, <<"dc1_events">>}, durable]},
{'queue.bind', [
{exchange, <<"events_forwarding_exchange">>},
{queue, <<"dc1_events">>},
{arguments, [
{"route_to_dc1", longstr, "true"}
]}
]},
{'exchange.bind', [
{exchange, <<"events_forwarding_exchange">>},
{exchange, <<"events_local_exchange">>},
{arguments, [
{"x-match", longstr, "any"},
{"route_to_local", longstr, "true"},
{"route_to_dc2", longstr, "true"}
]}
]}

With the above configuration, the broker fails to start and emits the following error:

=INFO REPORT==== 10-Nov-2011::16:03:35 ===
application: rabbitmq_shovel
exited: {{invalid_shovel_configuration,master_events_shovel,
{invalid_parameter_value,sources,
{unknown_fields,'exchange.bind',[exchange]}}},
{rabbit_shovel,start,[normal,[]]}}
type: permanent

What's the right way set up an exchange binding in rabbitmq.config? - I am running RabbitMQ 2.6.1.

Thanks,
Tom

Tom,
The field names need to match what is in the spec. See
http://www.rabbitmq.com/amqp-0-9-1-reference.html#exchange.bind - so
instead of having two 'exchange' fields you need one 'destination' and
one 'source' field.

Matthias.

While the description may have been available in the spec, I suppose it was lost on me that the configuration file itself is somehow an implementation of that spec. So a couple follow up questions:

* Do all the names / parameters in the specification correspond precisely with syntax in rabbitmq.config?

* If Exchange to Exchange Bindings are listed in the "extensions" section of the RabbitMQ documentation here: http://www.rabbitmq.com/extensions.html (presumedly non-standard), why would the feature also be present in the specification link you provided?

* A 'how-to' showing exchange-to-exchange binding in the shovel pages would be golden; seems it would be a fairly common scenario.

-Tom

Tom,
Yes, modulo syntactic substitutions to make names etc more erlang-ish.
Specifically '-' is mapped to '_'.
The reference guide includes rabbit's protocol extensions. It says so at
the top, though perhaps that could be clearer.
The shovel documentation could certainly be improved.

Would you consider publishing a blog post after you've got it all
working? Looks like your use of the shovel is a bit more complex than
most, so I am sure other rabbit users would find it interesting.

Regards,

Matthias.