Design RabbitMQ routing for order events. The email service wants every order.* event, the EU warehouse wants only shipped orders in the EU, and the audit service wants every event of any kind. What exchange, routing keys and bindings do you use?

Use one durable topic exchange, for example events. Give routing keys a fixed structure such as <entity>.<action>.<region>. Examples: order.shipped.eu or order.created.us.

Each service declares its own durable queue and binds it with a pattern:

• Email queue: binds with order.#. Every order event reaches it, whatever comes after order.
• EU warehouse queue: binds with order.shipped.eu.
• Audit queue: binds with #, which matches every routing key.

All instances of one service consume from that service's queue. So they share the work between them.

Decide the key format up front and document it. Bindings depend on the word positions. Adding a region later is cheap. But changing the order of the words breaks existing bindings.