Building Microservices with Go

Dead Letter Queue

This second queue is commonly called a dead letter queue, a dead letter queue is specific to the queue from where the message originated, if we had a queue named order_service_emails then we would create a second queue called order_service_emails_deadletter. The purpose of this is so that we can examine the failed messages on this queue to assist us with debugging the system, there is no point in knowing an error has occurred if we do not know what that error is and because we have been appending the error details direct to the message body we have this history right where we need it.

We can see that the message has failed because we have exceeded our quota in the mail API, we also have the date and time of when the error ...