Receive Messages from AWS SQS using Go

development golang aws sqs

In order to work with AWS SQS using Go, we will use github.com/aws/aws-sdk-go-v2. In this gist, we will use the aws-sdk-go-v2 package to receive messages from a queue in AWS SQS. The complete source code for the snippet is available here https://github.com/abvarun226/blog-source-code/tree/master/receive-messages-from-aws-sqs-using-go

In order to test the snippet, we will use localstack to run SQS emulator in a docker container on the laptop. The container exposes SQS endpoint on port 4566. The snippet will then receive a message from queue first-queue in SQS.

In order to start the localstack container, you will need to first install localstack:


$ pip install localstack

Localstack provides a fully functional local AWS cloud stack. It is a cloud service emulator that runs in a single container on a laptop or a development machine.

In order to start the AWS services, run:


$ localstack start -d

You can check the status of the services by running:


$ localstack status services


package main

import (
	"context"
	"flag"
	"log"

	"github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/config"
	"github.com/aws/aws-sdk-go-v2/service/sqs"
	"github.com/aws/aws-sdk-go-v2/service/sqs/types"
)

type SQSQueueAPI interface {
	GetQueueUrl(ctx context.Context,
		params *sqs.GetQueueUrlInput,
		optFns ...func(*sqs.Options)) (*sqs.GetQueueUrlOutput, error)

	ReceiveMessage(ctx context.Context,
		params *sqs.ReceiveMessageInput,
		optFns ...func(*sqs.Options)) (*sqs.ReceiveMessageOutput, error)
}

func GetQueueURL(c context.Context, api SQSQueueAPI, input *sqs.GetQueueUrlInput) (*sqs.GetQueueUrlOutput, error) {
	return api.GetQueueUrl(c, input)
}

func ReceiveMessage(c context.Context, api SQSQueueAPI, input *sqs.ReceiveMessageInput) (*sqs.ReceiveMessageOutput, error) {
	return api.ReceiveMessage(c, input)
}

// creates an sqs client.
func client(ctx context.Context, awsURL, region string) *sqs.Client {
	// customResolver is required here since we use localstack and need to point the aws url to localhost.
	customResolver := aws.EndpointResolverWithOptionsFunc(func(service, region string, options ...interface{}) (aws.Endpoint, error) {
		return aws.Endpoint{
			PartitionID:   "aws",
			URL:           awsURL,
			SigningRegion: region,
		}, nil

	})

	// load the default aws config along with custom resolver.
	cfg, err := config.LoadDefaultConfig(ctx, config.WithEndpointResolverWithOptions(customResolver))
	if err != nil {
		log.Fatalf("configuration error: %v", err)
	}

	return sqs.NewFromConfig(cfg)
}

// receive a message from a queue.
func recvMessage(ctx context.Context, c *sqs.Client, queue *string) {
	// Get the URL for the queue
	input := &sqs.GetQueueUrlInput{
		QueueName: queue,
	}
	resultGet, err := GetQueueURL(ctx, c, input)
	if err != nil {
		log.Printf("error getting the queue URL: %v", err)
		return
	}
	queueURL := resultGet.QueueUrl

	// Receive a message with attributes to the given queue
	recvInput := &sqs.ReceiveMessageInput{
		QueueUrl:              queueURL,
		MessageAttributeNames: []string{"All"},
		MaxNumberOfMessages:   1,
		VisibilityTimeout:     int32(10),
	}

	msg, err := ReceiveMessage(ctx, c, recvInput)
	if err != nil {
		log.Printf("error receiving messages: %v", err)
		return
	}

	if msg.Messages == nil {
		log.Printf("No messages found")
		return
	}

	log.Printf("Message ID: %s, Message Body: %s", *msg.Messages[0].MessageId, *msg.Messages[0].Body)
}

func main() {
	ctx := context.TODO()

	// name of the queue as a command line option.
	queue := flag.String("q", "", "name of the queue")
	flag.Parse()

	// queue cannot be empty string.
	if *queue == "" {
		log.Println("-q argument is required. Specify a name for the queue")
		return
	}

	awsURL := "http://127.0.0.1:4566"
	awsRegion := "us-west-2"

	// create aws client
	c := client(ctx, awsURL, awsRegion)

	// receive a message from the given queue
	recvMessage(ctx, c, queue)
}

Output:

export AWS_SECRET_ACCESS_KEY=foobar
➜  export AWS_ACCESS_KEY_ID=foobar

➜  go run main.go -q first-queue
2022/09/29 00:06:04 Message ID: ae5eca00-75cd-4316-a51a-5ea25dd74fe4, Message Body: article about sending a message to AWS SQS using Go

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