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Re-deliver Message with Limited Attempts¶

Example¶

The example below illustrates how to configure message re-delivery with limited attempts. You can use this flow both with the out-of-the-box configuration, and with Multiple Queue Dividing. Use the commands provided by the RabbitMQ management plugin.

Create oro.unprocessed Queue¶

Create an oro.unprocessed queue that should act as a storage with messages that failed more than the maximum available attempts.

rabbitmqadmin declare queue --host=$HOST --user=$USER --password=$PASSWORD --vhost=$VHOST \
name="oro.unprocessed" durable=true arguments='{"x-max-priority": 4}'

Re-Declare oro.default.delayed Exchange¶

Re-declare the oro.default.delayed exchange to make sure that it is declared and does not have any additional bindings.

rabbitmqadmin delete exchange --host=$HOST --user=$USER --password=$PASSWORD --vhost=$VHOST \
name="oro.default.delayed"

rabbitmqadmin declare exchange --host=$HOST --user=$USER --password=$PASSWORD --vhost=$VHOST \
name="oro.default.delayed" type="x-delayed-message" \
durable=true arguments='{"x-delayed-type": "fanout"}'

Declare oro.redelivery.control Exchange¶

After a delay timeout, when re-delivered messages pass to oro.default.delayed exchange, the exchange is routed to the oro.redelivery.control that checks the number of redelivered attempts.

rabbitmqadmin declare exchange --host=$HOST --user=$USER --password=$PASSWORD --vhost=$VHOST \
name="oro.redelivery.control" type="headers" durable=true \
arguments='{"alternate-exchange": "oro.default"}'

rabbitmqadmin declare binding --host=$HOST --user=$USER --password=$PASSWORD --vhost=$VHOST \
source="oro.default.delayed" destination="oro.redelivery.control" destination_type="exchange"

Configure Count of Re-Delivery Attempts¶

Set the maximum number of message re-delivery attempts. There are 5 in the example below.

rabbitmqadmin declare binding --host=$HOST --user=$USER --password=$PASSWORD --vhost=$VHOST \
source="oro.redelivery.control" destination="oro.unprocessed" destination_type="queue" \
arguments='{"oro-redeliver-count": 5}'

What Next?¶

From time to time, collect metrics on how many messages there are in the oro.unprocessed queue. If the number of messages grows, check the application logs and fix the problem manually. When a problem is fixed, route the messages using the RabbitMQ Shovel Plugin back to the oro.default exchange.

Possible Problems¶

If the current configuration was applied to an application that had been in production for some time, some of messages can contain headers with oro-redeliver-count more that 5. In this case, manually check the message redelivery count:

rabbitmqadmin get queue="oro.default" --host=$HOST --user=$USER --password=$PASSWORD --vhost=$VHOST

In addition, declare an additional binding for the oro.redelivery.control exchange. For example, if oro-redeliver-count equals 153, then:

rabbitmqadmin declare binding --host=$HOST --user=$USER --password=$PASSWORD --vhost=$VHOST \
source="oro.redelivery.control" destination="oro.unprocessed" destination_type=queue \
arguments='{"oro-redeliver-count": 154}' routing_key="additional_binding"

Once the failed message is caught, remove additional binding:

# get properties key for additional binding
rabbitmqadmin list bindings --host=$HOST --user=$USER --password=$PASSWORD --vhost=$VHOST \
source destination routing_key properties_key | grep "properties_key\|additional_binding"

rabbitmqadmin delete binding --host=$HOST --user=$USER --password=$PASSWORD --vhost=$VHOST \
source="oro.redelivery.control" destination="oro.unprocessed" destination_type=queue \
properties_key='additional_binding~UFQ6EQ'

For more information, see the following external resources: