This module should be used to start a Producer.

Example usage

ℹ️ The following example assumes that the "customer" exchange already exists.

defmodule RabbitSample.CustomerProducer do
  @moduledoc """
  Publishes pre-configured events onto the "customer" exchange.
  """

  use RabbitMQ.Producer, exchange: "customer", worker_count: 3

  @doc """
  Publishes an event routed via "customer.created".
  """
  def customer_created(customer_id) when is_binary(customer_id) do
    opts = [
      content_type: "application/json",
      correlation_id: UUID.uuid4()
    ]

    payload = Jason.encode!(%{v: "1.0.0", customer_id: customer_id})

    publish("customer.created", payload, opts)
  end
end

Behind the scenes, a dedicated AMQP.Connection is established, and a pool of RabbitMQ.Producer.Workers is started, resulting in a supervision tree similar to the one below.

ℹ️ To see which options can be passed as opts to publish/3, visit https://hexdocs.pm/amqp/AMQP.Basic.html#publish/5.

Start under your existing supervision tree as normal:

children = [
  RabbitSample.CustomerProducer
  # ... start other children
]

opts = [strategy: :one_for_one, name: RabbitSample.Supervisor]
Supervisor.start_link(children, opts)

Call the exposed methods from your application:

RabbitSample.CustomerProducer.customer_created(customer_id)

⚠️ All Producer workers implement "reliable publishing", which means that publisher confirms are always enabled and handled asynchronously, striking a delicate balance between performance and reliability.

To understand why this is important, please refer to the reliable publishing implementation guide.

You can implement the optional handle_publisher_ack_confirms/1 and handle_publisher_nack_confirms/1 callbacks to receive publisher confirmations.

Configuration

The following options can be used with RabbitMQ.Producer;

• :exchange; messages will be published onto this exchange. Required.
• :worker_count; number of workers to be spawned. Defaults to 3.