Knowledge Base

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====== RabbitMQ in Docker ======

Supporting repo is [[https://github.com/jfcarr/rabbitmq-docker|here]]. (Includes a [[http://www.celeryproject.org/|Celery]] example)

If you don’t already have Docker installed, you can find instructions [[:docker_linux|here]].
===== Setup and Run =====

Pull the RabbitMQ docker container:

<code bash>
docker pull rabbitmq
</code>

Startup for RabbitMQ docker container:

<code bash>
sudo docker run -d --hostname my-rabbit --name some-rabbit -p 5672:5672 rabbitmq:3
</code>

<WRAP center round important 60%>
The port mapping (5672:5672) is not included in the instructions on Docker Hub, but it’s required for the Python send/receive scripts to work.
</WRAP>

===== Simple Test in Python =====

You’ll need to install the [[https://pypi.org/project/pika/|Pika]] library before you run the send/receive scripts:

<code bash>
sudo pip3 install pika --upgrade
</code>

Python script to send a message:

<file python send.py>
    #!/usr/bin/env python3
    import pika
     
    connection = pika.BlockingConnection(pika.ConnectionParameters('localhost'))
    channel = connection.channel()
     
    channel.queue_declare(queue='hello')
     
    channel.basic_publish(exchange='', routing_key='hello', body='Hello World!')
    print(" [x] Sent 'Hello World!'")
    connection.close()
</file>

Python script to receive messages:

<file python receive.py>
    #!/usr/bin/env python3
    import pika
     
    connection = pika.BlockingConnection(pika.ConnectionParameters('localhost'))
    channel = connection.channel()
     
    channel.queue_declare(queue='hello')
     
    def callback(ch, method, properties, body):
    	print(" [x] Received %r" % body)
     
    channel.basic_consume(queue='hello', on_message_callback=callback, auto_ack=True)
     
    print(' [*] Waiting for messages. To exit press CTRL+C')
    channel.start_consuming()
</file>

===== Simple Test in Go =====

First, install amqp using go get:

<code bash>
go get github.com/streadway/amqp
</code>

Then, use this to send a message:

<file go send.go>
    package main
     
    import (
    	"log"
     
    	"github.com/streadway/amqp"
    )
     
    func failOnError(err error, msg string) {
    	if err != nil {
    		log.Fatalf("%s: %s", msg, err)
    	}
    }
     
    func main() {
    	conn, err := amqp.Dial("amqp://guest:guest@localhost:5672/")
    	failOnError(err, "Failed to connect to RabbitMQ")
    	defer conn.Close()
     
    	ch, err := conn.Channel()
    	failOnError(err, "Failed to open a channel")
    	defer ch.Close()
     
    	q, err := ch.QueueDeclare(
    		"hello", // name
    		false,   // durable
    		false,   // delete when unused
    		false,   // exclusive
    		false,   // no-wait
    		nil,     // arguments
    	)
    	failOnError(err, "Failed to declare a queue")
     
    	body := "Hello World!"
    	err = ch.Publish(
    		"",     // exchange
    		q.Name, // routing key
    		false,  // mandatory
    		false,  // immediate
    		amqp.Publishing{
    			ContentType: "text/plain",
    			Body:        []byte(body),
    		})
    	log.Printf(" [x] Sent %s", body)
    	failOnError(err, "Failed to publish a message")
    }
</file>

And use this to receive messages:

<file go receive.go>
    package main
     
    import (
    	"log"
     
    	"github.com/streadway/amqp"
    )
     
    func failOnError(err error, msg string) {
    	if err != nil {
    		log.Fatalf("%s: %s", msg, err)
    	}
    }
     
    func main() {
    	conn, err := amqp.Dial("amqp://guest:guest@localhost:5672/")
    	failOnError(err, "Failed to connect to RabbitMQ")
    	defer conn.Close()
     
    	ch, err := conn.Channel()
    	failOnError(err, "Failed to open a channel")
    	defer ch.Close()
     
    	q, err := ch.QueueDeclare(
    		"hello", // name
    		false,   // durable
    		false,   // delete when unused
    		false,   // exclusive
    		false,   // no-wait
    		nil,     // arguments
    	)
    	failOnError(err, "Failed to declare a queue")
     
    	msgs, err := ch.Consume(
    		q.Name, // queue
    		"",     // consumer
    		true,   // auto-ack
    		false,  // exclusive
    		false,  // no-local
    		false,  // no-wait
    		nil,    // args
    	)
    	failOnError(err, "Failed to register a consumer")
     
    	forever := make(chan bool)
     
    	go func() {
    		for d := range msgs {
    			log.Printf("Received a message: %s", d.Body)
    		}
    	}()
     
    	log.Printf(" [*] Waiting for messages. To exit press CTRL+C")
    	<-forever
    }
</file>

{{tag>docker}}