Event Exchange Plugin

Overview

Client connection, channels, queues, consumers, and other parts of the system naturally generate events. For example, when a connection is accepted, authenticated and access to the target virtual host is authorised, it will emit an event of type connection_created. When a connection is closed or fails for any reason, a connection_closed event is emitted.

Monitoring and auditing services can be interested in observing those events. RabbitMQ has a minimalistic mechanism for event notifications that can be exposed to RabbitMQ clients with a plugin.

Consuming Internal Events with rabbitmq-event-exchange Plugin

rabbitmq-event-exchange is a plugin that consumes internal events and re-publishes them to a topic exchange, thus exposing the events to clients (applications).

To consume the events, an application needs to declare a queue, bind it to a special system exchange and consume messages.

It declares a topic exchange called amq.rabbitmq.event in the default virtual host. All events are published to this exchange with routing keys like 'exchange.created', 'binding.deleted' etc, so you can subscribe to only the events you're interested in.

The exchange behaves similarly to amq.rabbitmq.log: everything gets published there; if you don't trust a user with the information that gets published, don't allow them access.

The plugin requires no configuration, just activate it:

rabbitmq-plugins enable rabbitmq_event_exchange

Each event has various properties associated with it. These are translated into AMQP 0-9-1 data encoding and inserted in the message headers. The message body is always blank.

Usage Guidelines

important

In most cases, setting a max length limit of a few thousand on the queues used to consume these events would prevent unnecessary resource use.

The event exchange plugin is typically used for audit of internal events. An application can bind a queue, a stream, or a set of queues (or streams) to this exchange and store a history of generated events. Therefore, this special exchange can be considered a form of a structured log.

A surge in the number of inbound connections, connection churn, channel churn, or queue churn will produce a large number of events. In environments where consumers on the internal event queue can be absent for long periods of time, the queue can accumulate a substantial backlog.

In most cases, setting a max length limit of a few thousand on the queues used to consume these events would prevent unnecessary resource use.

Events

RabbitMQ and related plugins produce events with the following routing keys:

RabbitMQ Broker

Queue, Exchange and Binding events:

• queue.created
• queue.deleted
• exchange.created
• exchange.deleted
• binding.created
• binding.deleted

Connection and Channel events:

• connection.created
• connection.closed
• channel.created
• channel.closed

Consumer events:

• consumer.created
• consumer.deleted

Policy and Parameter events:

• policy.set
• policy.cleared
• parameter.set
• parameter.cleared

Virtual host events:

• vhost.created
• vhost.deleted

User related events:

• user.authentication.success
• user.authentication.failure
• user.created
• user.deleted
• user.password.changed
• user.password.cleared
• user.tags.set

Permission events:

• permission.created
• permission.deleted

Shovel Plugin

Worker events:

• shovel.worker.status
• shovel.worker.removed

Federation Plugin

Link events:

• federation.link.status
• federation.link.removed

Example

There is a usage example using the Java client in the rabbitmq-event-exchange repository.