ExKonsument

A library for RabbitMQ producers and consumers.

Installation

Just put it in your mix.exs and mix deps.get.

defdepsdo[{:exkonsument,"~> 3.2"}]end

If you have trouble compiling your app make sure to override the lager and ranch_proxy_protocol dependencies in your application's mix.exs file:

defdepsdo[{:exkonsument,"~> 3.2"},{:lager,"~> 3.6.7",override: true},{:ranch_proxy_protocol,"~> 2.0",override: true}]end

Usage

RabbitMQ connection

To open a connection to RabbitMQ, start an ExKonsument.Connection process. You can put this in your supervisor. The connection settings can be configured in your config files like this:

config:exkonsument,:connection_string,"amqp://user:password@yourhost:1234"

If you don't configure ExKonsument, it uses amqp://localhost:5672 as the default. The connection must be passed to producers/consumers later.

Connection sharing

You can share a connection between multiple consumers or producers, but never share a connection between producers and consumers. Due to the producers being async, this could lead to weird behaviour in case of errors.

Consumer

Basically you just have to call ExKonsument.Consumer.start_link and supply an %ExKonsument.Consumer{} struct. It is recommended to wrap all necessary information in a dedicated module like this:

defmoduleYourConsumerdo@queue%ExKonsument.Queue{name: "yourapp.queue",options: [durable: true]}@exchange%ExKonsument.Exchange{name: "yourexchange",type: topic,options: [durable: true]}@routing_keys["your.routing.key"]defstart_link(opts)doExKonsument.Consumer.start_link(consumer_config(),opts)enddefpprocess_message(payload,_opts,state)do# ... do stuff:ok# :ok will ack the message# :requeue will requeue the message# any other return value rejects it, only requeueing it if it wasn't# redelivered alreadyenddefpconsumer_configdo%ExKonsument.Consumer{queue: @queue,exchange: @exchange,routing_keys: @routing_keys,handling_fn: &process_message/3,connection: YourApp.Connection,state: %{}}endend

Producer

This is similar to the consumer, just that you call ExKonsument.Producer.start_link instead. Below is an example:

defmoduleYourProducerdo@exchange%ExKonsument.Exchange{name: "yourexchange",type: topic,options: [durable: true]}defstart_link(opts)doExKonsument.Producer.start_link(producer_config(),opts)enddefpublish_message(pid)doExKonsument.Producer.publish(pid,"routing.key",%{payload: "as map"})enddefpproducer_configdo%ExKonsument.Producer{exchange: @exchange,connection: YourApp.Connection}endend