Quorum queues (recommended) in RabbitMQ - Commands & Configuration

Introduction

Quorum queues in RabbitMQ help keep your messages safe even if some servers fail. They do this by copying messages across multiple servers, so your data is not lost if one server goes down.

When you want to make sure messages are not lost during server crashes.

When you need a reliable queue that can handle server restarts without losing data.

When you want to replace classic mirrored queues with a more stable and easier to manage option.

When your application requires high availability and data safety for message delivery.

When you want automatic recovery of queues after network or server failures.

Config File - quorum-queue-policy.json

quorum-queue-policy.json

{
  "policies": [
    {
      "name": "quorum-queue-policy",
      "pattern": "^quorum-",
      "definition": {
        "queue-type": "quorum"
      },
      "priority": 1,
      "apply-to": "queues"
    }
  ]
}

This JSON file defines a policy for RabbitMQ that applies to all queues starting with 'quorum-'. It sets their type to 'quorum', which means these queues will use the quorum queue mechanism for better reliability and data safety.

The pattern key matches queue names, definition sets the queue type, priority decides the policy's importance, and apply-to specifies it applies to queues.

Commands

This command creates a policy named 'quorum-queue-policy' that matches all queues starting with 'quorum-' and sets their type to quorum. This ensures those queues use the quorum mechanism for reliability.

Terminal

rabbitmqctl set_policy quorum-queue-policy "^quorum-" '{"queue-type":"quorum"}' --priority 1 --apply-to queues

Expected Output

Setting policy "quorum-queue-policy" for pattern "^quorum-" to "{\"queue-type\":\"quorum\"}" with priority 1

→

--priority 1 - Sets the priority of this policy to 1 to override lower priority policies

→

--apply-to queues - Applies this policy only to queues, not exchanges

This command creates a new durable queue named 'quorum-myqueue'. Because of the policy, this queue will be a quorum queue, ensuring message safety and replication.

Terminal

rabbitmqadmin declare queue name=quorum-myqueue durable=true

Expected Output

{

  "name": "quorum-myqueue",

  "vhost": "/",

  "durable": true,

  "auto_delete": false,

  "arguments": {},

  "node": "rabbit@localhost"

}

This command lists all queues with their names, types, and durability. It helps verify that 'quorum-myqueue' is created as a quorum queue and is durable.

Terminal

rabbitmqctl list_queues name type durable

Expected Output

Listing queues ...

quorum-myqueue	quorum	true

This command removes the 'quorum-queue-policy' policy. Use this if you want to stop applying quorum queue settings to matching queues.

Terminal

rabbitmqctl clear_policy quorum-queue-policy

Expected Output

Cleared policy "quorum-queue-policy"

Key Concept

If you remember nothing else from quorum queues, remember: they replicate messages safely across servers to prevent data loss during failures.

Common Mistakes

Creating queues without the policy and expecting them to be quorum queues.

Queues default to classic type unless a policy or argument sets them to quorum, so they won't have replication or safety features.

Always create a policy that sets 'queue-type' to 'quorum' for queues you want to be quorum queues, or specify the type when declaring the queue.

Using non-durable queues with quorum type.

Quorum queues require durability to ensure messages survive server restarts; non-durable queues lose messages on restart.

Always declare quorum queues with durable=true to keep messages safe.

Not verifying queue type after creation.

Without checking, you might think your queue is quorum but it could be classic, missing replication benefits.

Use 'rabbitmqctl list_queues' to confirm the queue type is 'quorum' after creation.

Summary

Set a policy to mark queues starting with 'quorum-' as quorum queues for replication and safety.

Create durable queues that match the policy to get quorum queue benefits.

Verify queue type with 'rabbitmqctl list_queues' to ensure correct setup.