iktech/dlq-handler-service repository overview

⁠DLQ Handler Service

This service is designed to handle RabbitMQ Dead Letter Queue messages. The idea behind this service is to attempt to re-process messages sent to the DLQ number of times (default 5, but could be configured using rabbitmq.failureThreshold parameter). Each time DLQ Handler attempts to send the message back to the original exchange, it will delay resending. The time delay is calculated using two parameters (both in seconds):

• rabbitmq.initialDelay
• rabbitmq.multiplier

Service uses the following formula:

    delay = initialDelay + (initialDelay * multiplier * (attempt - 1))

The attempt in this case is the index of the current attempt to re-send message back to original exchange.

⁠Configuration Parameters

Service supports two types of configuration:

• via configuration file
• via environment variables

Environment variables taking precedence over configuration in case of both are used. The configuration file is hierarchical and can be either in YAML or JSON format. Application searches for the job.yaml or job.json files in two locations:

• /etc/dlq-handler (Linux only)
• local directory where executable file resides

The following table describes the configuration parameters, with . delimiting levels of hierarchy. I.e. property name rabbitmq.username will be translated into either "rabbitmq": {"username": "value"} in JSON or the following structure in YAML:

    rabbitmq:
      username: value