RabbitMQ Shovel config with Alternate-Exchange - configuration

Question

I'm trying to configure the Shovel plugin for RabbitMQ with a list of declarations. I have configured my remote exchange to have an alternate-exchange when I created it.
My problem is that I can't get the config file for shovel to include this argument so RabbitMQ crashes upon startup.
This is what my config looks like:
[
{mnesia, [{dump_log_write_threshold, 100}]},
{rabbit, [{vm_memory_high_watermark, 0.4}]},
{rabbitmq_shovel,
[{shovels,
[{call_stats_shovel,
[{sources, [{broker, "amqp://guest:guest#localhost:5672/test"},
{declarations,
[{'queue.declare', [{queue, <<"incoming">>}, durable]},
{'exchange.declare',[{exchange, <<"my-exchange-topic">>},{type, <<"topic">>},durable]},
{'queue.bind',[{exchange, <<"my-exchange-topic">>},{queue, <<"incoming">>}]}
]}]},
{destinations, [{broker, "amqp://guest:guest#172.16.3.162:5672/blah"},
{declarations,
[
{'queue.declare',[{queue, <<"billing">>},durable]},
{'exchange.declare',[{exchange, <<"my-exchange-topic">>},{type, <<"topic">>},{alternate_exchange, <<"alt">>}, durable]},
{'queue.bind',[{exchange, <<"my-exchange-topic">>},{queue, <<"billing">>},{routing_key, <<"physical">>}]}
]}
]},
{queue, <<"incoming">>},
{ack_mode, no_ack},
{publish_properties, [{delivery_mode, 2}]},
{reconnect_delay, 5}
]}
]
}]
}
].
The problem is on the destination exchange called my-exchange-topic. If I take out the declarations section then the config file works.
This is the error:
=INFO REPORT==== 31-Jul-2012::12:15:25 ===
application: rabbitmq_shovel
exited: {{invalid_shovel_configuration,call_stats_shovel,
{invalid_parameter_value,destinations,
{unknown_fields,'exchange.declare',
[alternate_exchange]}}},
{rabbit_shovel,start,[normal,[]]}}
type: permanent
If I leave the alternate_exchange section out of the declaration I get this error in RabbitMQ web management:
{{shutdown,
{server_initiated_close,406,
<<"PRECONDITION_FAILED - inequivalent arg 'alternate-exchange'for exchange 'my-exchange-topic' in vhost 'blah':
received none but current is the value 'alt' of type 'longstr'">>}},
{gen_server,call,
[<0.473.0>,
{call,
{'exchange.declare',0,<<"my-exchange-topic">>,<<"topic">>,false,
true,false,false,false,[]},
none,<0.444.0>},
infinity]}}

Answer 1

For anyone looking at how to configure exchanges and queues that require additional arguments you do it like this:
{'exchange.declare',[{exchange, <<"my-exchange-topic">>},{type, <<"topic">>}, durable, {arguments, [{<<"alternate-exchange">>, longstr, <<"alternate-exchange">>}]} ]},
you can do a similar thing with queues:
{'queue.declare',[{queue, <<"my-queue">>},durable, {arguments, [{<<"x-dead-letter-exchange">>, longstr, <<"dead-letter-queue">>}]}]}

Answer 2

For clarification of the comment above, in case of an exchange2exchange shovel, the config would be:
{'exchange.declare',[{exchange, <<"my-exchange-topic">>},{type, <<"topic">>}, durable, {arguments, [{<<"alternate-exchange">>, longstr, <<"name-of-your-alternate-exchange">>}]} ]},