RabbitMQ

RabbitMQ is an open-source message broker that sits between the parts of a system that produce work and the parts that do it. A producer publishes a message to an exchange, the exchange matches the message's routing key against its bindings, and every matching queue holds the message until a consumer takes it. That indirection is the point: producers never need to know who consumes their messages, and a queue absorbs bursts that would otherwise overwhelm a downstream service.

Why RabbitMQ?

• Durable buffering: A queue holds work while consumers are slow, restarting, or offline, so a traffic spike becomes a backlog to work through rather than dropped requests.
• Flexible routing: Direct exchanges route on an exact key, topic exchanges on wildcard patterns like orders.*, fanout exchanges to every bound queue, and headers exchanges on message metadata.
• Delivery guarantees: Messages and queues can be marked durable so they survive a broker restart, and unacknowledged messages return to the queue when a consumer dies mid-work.
• Failure handling built in: Dead-letter exchanges, per-message TTLs, and queue length limits let you decide up front what happens to work that expires, overflows, or repeatedly fails.
• Runs anywhere: Self-hosted on your own infrastructure, or managed through providers such as CloudAMQP and Amazon MQ.

Using RabbitMQ in Sim

Sim talks to RabbitMQ over its Management HTTP API — the same interface behind the RabbitMQ management UI — using the management plugin's base URL plus a username and password. There is no AMQP connection to configure and no client library to install; if you can reach the management UI in a browser, Sim can reach your broker.

Key benefits of using RabbitMQ in Sim:

• Publish from any workflow step: Hand off enriched or classified data to an existing service by publishing to an exchange, without that service needing to know Sim exists.
• Inspect queues without consuming them: The default acknowledgement mode requeues what it reads, so an agent can examine a dead-letter backlog and leave the messages exactly where they were.
• Triage failures with an agent: Read a dead-letter queue, let an agent group messages by root cause, and route the summary to Slack, PagerDuty, or a table.
• Monitor broker health on a schedule: List queues and read the broker overview to catch a queue whose depth is climbing or that has lost all its consumers.
• Declare topology as part of a workflow: Create queues, set arguments such as quorum type or dead-lettering, and bind them to exchanges as an automated setup step.

Before you start

• The management plugin must be enabled and reachable from Sim. It listens on port 15672 by default and is separate from the AMQP port (5672). Self-hosted brokers enable it with rabbitmq-plugins enable rabbitmq_management; managed providers expose it as a management or console URL.
• The management URL must use https unless the broker is on a loopback host. Credentials travel on every request as HTTP basic auth, so plain http to a remote broker would put them on the wire in the clear — Sim rejects it rather than sending them.
• The user you authenticate as needs the management tag at minimum, plus read and write permissions on the virtual host you target. Administrative operations require broader permissions.
• Publishing and reading messages over the HTTP API is convenient but not a high-throughput transport — RabbitMQ opens a new connection per request. It is well suited to workflow-rate traffic, inspection, and operational automation; a service consuming thousands of messages per second should use an AMQP client instead.
• Queue statistics such as message and consumer counts are collected on an interval, so a queue declared moments ago may report them as empty until the broker's next sample.
• Reading messages is bounded per call so one retrieval cannot exceed Sim's response limit. A batch is capped at 50 messages, payloads are truncated (each message reports whether it was), and a large batch shortens payloads further. AMQP properties and headers are returned in full — the broker offers no way to truncate them — so retrieving several messages carrying very large headers may still hit the limit; lower the count if that happens.

Usage Instructions

Connect agents to a RabbitMQ broker through its Management HTTP API. Publish messages to exchanges, read messages off queues, declare queues, exchanges, bindings, and policies, and inspect broker health, queue depth, consumers, connections, and cluster nodes. Works with self-hosted brokers and managed offerings such as CloudAMQP as long as the management plugin is reachable.

Actions

RabbitMQ Publish Message

Publish a message to a RabbitMQ exchange with a routing key. Reports whether the message was routed to at least one queue.

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RabbitMQ Get Messages

Retrieve messages from a RabbitMQ queue. Defaults to requeueing the messages so they stay available to real consumers.

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RabbitMQ List Queues

List queues in a RabbitMQ virtual host with their depth, consumer count, and configuration.

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RabbitMQ Get Queue

Read a single RabbitMQ queue, including its depth, consumer count, and declaration settings.

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RabbitMQ Create Queue

Declare a RabbitMQ queue. Declaring a queue that already exists with the same settings succeeds without changing it.

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RabbitMQ Delete Queue

Delete a RabbitMQ queue and every message still in it. Can be guarded so the delete only happens when the queue is unused or empty.

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RabbitMQ Purge Queue

Discard every ready message in a RabbitMQ queue while leaving the queue itself in place.

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RabbitMQ List Exchanges

List exchanges in a RabbitMQ virtual host with their type and declaration settings.

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RabbitMQ Get Exchange

Read a single RabbitMQ exchange and the settings it was declared with.

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RabbitMQ Create Exchange

Declare a RabbitMQ exchange. Declaring an exchange that already exists with the same settings succeeds without changing it.

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RabbitMQ Delete Exchange

Delete a RabbitMQ exchange and every binding attached to it. Publishers targeting it will fail afterwards.

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RabbitMQ List Bindings

List the bindings that route messages into a RabbitMQ queue, including the implicit default-exchange binding.

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RabbitMQ List Exchange Bindings

List everything an exchange routes to, so you can see which routing keys reach which queues.

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RabbitMQ Create Binding

Bind a queue or another exchange to a RabbitMQ exchange so messages matching a routing key are routed to it.

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RabbitMQ Delete Binding

Remove a binding so an exchange stops routing its matching messages to that destination.

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RabbitMQ Get Overview

Read broker-wide RabbitMQ status: version, cluster name, object totals, queue depth totals, and message rates.

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RabbitMQ Health Check

Run one of the broker health checks and report whether it passed. A failing check is a normal result, not a tool error.

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RabbitMQ List Nodes

List the cluster nodes with memory, disk, file-descriptor, and alarm state. A fired alarm blocks publishers broker-wide.

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RabbitMQ List Virtual Hosts

List the virtual hosts on the broker with their message totals, so you can discover which scopes exist.

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RabbitMQ List Connections

List client connections to the broker with their user, state, and channel count. Connections are cluster-wide, not scoped to one virtual host.

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RabbitMQ List Channels

List open channels with their prefetch limit and unacknowledged message count, which is where stalled consumers show up. Channels are cluster-wide, not scoped to one virtual host.

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RabbitMQ List Consumers

List the consumers subscribed in a virtual host. An empty result for a queue with a backlog means nothing is processing it.

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RabbitMQ List Policies

List the policies in a virtual host. Policies are how dead-lettering, TTLs, and length limits get applied to matching queues and exchanges.

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RabbitMQ Create Policy

Create or replace a RabbitMQ policy, applying settings such as dead-lettering, TTLs, or length limits to every queue or exchange whose name matches a pattern.

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RabbitMQ Delete Policy

Delete a RabbitMQ policy. Every queue and exchange it matched immediately loses the settings it applied.

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