Explain the internal working of the RabbitMQ shovel plugin?

The shovel plugin runs a small, resilient client inside (or alongside) RabbitMQ that behaves like a well-behaved consumer on one broker and a well-behaved producer on another, continuously moving messages between them.

1. It opens its own AMQP connection to a source broker/queue and consumes messages from it with manual acknowledgment.
2. For each message received, it republishes that message to a configured destination exchange (possibly on a completely different broker or cluster).
3. Only after the destination confirms the publish does the shovel acknowledge the original message back to the source, so a failure mid-transfer results in redelivery rather than data loss.
4. It automatically reconnects and resumes if either side's connection drops.

Shovels can be configured statically (in config files) or dynamically (via the management API/UI), and they are commonly used for one-off migrations, bridging on-prem and cloud clusters, or moving a specific queue's traffic without wiring up full federation.