Binding keys and routing keys in RabbitMQ - Commands & Configuration

Introduction

When sending messages in RabbitMQ, you need a way to decide which messages go to which queues. Binding keys and routing keys help match messages to queues so the right consumers get the right messages.

When you want to send messages to specific queues based on message content

When you need to filter messages so only certain queues receive them

When you want to use a topic exchange to route messages by patterns

When you want to connect multiple queues to one exchange with different filters

When you want to organize message flow in a publish-subscribe system

Config File - rabbitmq_binding_example.sh

rabbitmq_binding_example.sh

#!/bin/bash

# Declare a topic exchange named 'my_topic_exchange'
rabbitmqadmin declare exchange name=my_topic_exchange type=topic

# Declare two queues
rabbitmqadmin declare queue name=queue_errors durable=true
rabbitmqadmin declare queue name=queue_logs durable=true

# Bind queue_errors to the exchange with binding key 'error.*'
rabbitmqadmin declare binding source=my_topic_exchange destination=queue_errors routing_key=error.*

# Bind queue_logs to the exchange with binding key '*.log'
rabbitmqadmin declare binding source=my_topic_exchange destination=queue_logs routing_key=*.log

This script creates a topic exchange called my_topic_exchange. It then creates two queues: queue_errors and queue_logs. Each queue is bound to the exchange with a binding key pattern. queue_errors receives messages with routing keys starting with error., and queue_logs receives messages with routing keys ending with .log. This setup routes messages based on their routing keys matching the binding keys.

Commands

Create a topic exchange named 'my_topic_exchange' where messages will be sent and routed based on routing keys.

Terminal

rabbitmqadmin declare exchange name=my_topic_exchange type=topic

Expected Output

Successfully declared exchange 'my_topic_exchange'

→

type=topic - Defines the exchange type to route messages by pattern matching routing keys

Create a durable queue named 'queue_errors' to receive error messages.

Terminal

rabbitmqadmin declare queue name=queue_errors durable=true

Expected Output

Successfully declared queue 'queue_errors'

→

durable=true - Ensures the queue survives RabbitMQ restarts

Create a durable queue named 'queue_logs' to receive log messages.

Terminal

rabbitmqadmin declare queue name=queue_logs durable=true

Expected Output

Successfully declared queue 'queue_logs'

→

durable=true - Ensures the queue survives RabbitMQ restarts

Bind 'queue_errors' to the exchange with binding key 'error.*' so it receives messages with routing keys starting with 'error.'.

Terminal

rabbitmqadmin declare binding source=my_topic_exchange destination=queue_errors routing_key=error.*

Expected Output

Successfully declared binding from 'my_topic_exchange' to 'queue_errors' with routing key 'error.*'

→

routing_key=error.* - Filters messages to those with routing keys matching 'error.*'

Bind 'queue_logs' to the exchange with binding key '*.log' so it receives messages with routing keys ending with '.log'.

Terminal

rabbitmqadmin declare binding source=my_topic_exchange destination=queue_logs routing_key=*.log

Expected Output

Successfully declared binding from 'my_topic_exchange' to 'queue_logs' with routing key '*.log'

→

routing_key=*.log - Filters messages to those with routing keys matching '*.log'

Key Concept

Binding keys on queues and routing keys on messages work together to route messages to the right queues based on matching patterns.

Common Mistakes

Using the same string for binding key and routing key without understanding pattern matching

Messages may not be routed as expected because topic exchanges use patterns like '*' and '#' for matching

Use wildcards '*' and '#' in binding keys to match routing keys patterns properly

Binding queues to the wrong exchange type (e.g., direct instead of topic)

Routing keys are interpreted differently depending on exchange type, causing routing failures

Ensure the exchange type matches the routing logic you want, like 'topic' for pattern matching

Not declaring queues before binding them to exchanges

Bindings fail because the queue does not exist yet

Always declare queues before creating bindings

Summary

Create a topic exchange to route messages based on routing keys.

Declare queues that will receive messages filtered by binding keys.

Bind queues to the exchange with binding keys that use patterns to match routing keys.

Messages sent with routing keys matching binding keys are delivered to the correct queues.