RabbitMQ - a client for microservices

Overview

This library aims to simplify the creation of a rabbitMQ package on a Go service. Hopefully it will make your life easier.

Installation

To use this library you can simply import the package github.com/gbeletti/rabbitmq and run the command go mod tidy to download it or you can explicit run

go get github.com/gbeletti/rabbitmq

Usage

You can see a package example here. The main.go starts the service and the package queuerabbit uses this lib.

Connecting to rabbit

To get started import the package github.com/gbeletti/rabbitmq, call the function rabbitmq.NewRabbitMQ() and connect it to the rabbitMQ server.

import (
    "context"
    "log"
    "os"

    "github.com/gbeletti/rabbitmq"
)

var rabbit rabbitmq.RabbitMQ
rabbit = rabbitmq.NewRabbitMQ()

ctx, cancel = context.WithCancel(context.Background())

configConn := rabbitmq.ConfigConnection{
    URI:           "amqp://guest:guest@localhost:5672?heartbeat=30&connection_timeout=120",
    PrefetchCount: 1,
}

var setup rabbitmq.Setup = func() {
    // creates and consumes from queues
}

rabbitmq.KeepConnectionAndSetup(ctx, rabbit, configConn, setup)

The function KeepConnectionAndSetup will create a goroutine to keep the connection open until the context is canceled. It is important that the context is canceled on the shutdown of the service so it stops trying to keep the connection opened.

Shutting down gracefully

When the service is going down you must call the Close function to close all the connections gracefully.

ctx, cancelTimeout := context.WithTimeout(context.Background(), time.Second*30)
defer cancel()
var done chan struct{}
done = rabbit.Close(ctx)
<-done

It will stop receiving new messages and wait processing all the messages received from queue and publishing message to exchange or it will timeout after a given time.

Creating queues

Just create the configuration struct and call the CreateQueue function.

func createQueues(rabbit rabbitmq.QueueCreator) {
    config := rabbitmq.ConfigQueue{
        Name:       "test",
        Durable:    true,
        AutoDelete: false,
        Exclusive:  false,
        NoWait:     false,
        Args:       nil,
    }
    _, err := rabbit.CreateQueue(config)
    if err != nil {
        log.Printf("error creating queue: %s\n", err)
    }
}

Consuming from exchange

First create the configuration

config := rabbitmq.ConfigConsume{
    QueueName:         "test",
    Consumer:          "test",
    AutoAck:           false,
    Exclusive:         false,
    NoLocal:           false,
    NoWait:            false,
    Args:              nil,
    ExecuteConcurrent: true,
}

The option ExecuteConcurrent defines if the message received should run in a goroutine or not.

Then create the function to be executed upon getting a new message.

func receiveMessage(d *amqp.Delivery) {
    defer func() {
        if err := d.Ack(false); err != nil {
            log.Printf("error acking message: %s\n", err)
        }
    }()
    log.Printf("received message: %s\n", d.Body)
}

Every message sent to test queue will execute the receiveMessage function.

Finally run the Consume function in a goroutine

go func() {
    if err := rabbit.Consume(ctx, config, receiveMessage); err != nil {
        log.Printf("error consuming from queue: %s\n", err)
    }
}()

It is important that the context has cancel, so when it is canceled it will stop consuming messages from queue. You can share the same context used in the connection.

Reference

This library uses rabbitmq/amqp091-go. To better understand the options for the queues and exchanges I suggest their documentation.