AWS SQS

This tutorial will demonstrate how to use a AWS SQS trigger to invoke a function. We’ll assume you have Fission and Kubernetes installed. If not, please head over to the install guide.

You will also need AWS SQS setup which is reachable from the Fission Kubernetes cluster.

Installation

If you want to setup SQS on the Kubernetes cluster, you can use the information here or you can create queue using your aws account docs.

Also note that, if you are using localstack then it is only good for testing and dev environments and not for production usage.

Overview

Before we dive into details, let’s walk through overall flow of event and functions involved.

1. A Go producer function (producerfunc) or aws cli command which acts as a producer and drops a message in a SQS queue named input.
2. Fission SQS trigger activates and invokes another function (consumerfunc) with body of SQS message.
3. The consumer function (consumerfunc) gets body of message and returns a response.
4. Fission SQS trigger takes the response of consumer function (consumerfunc) and drops the message in a response queue named output. If there is an error, the message is dropped in error queue named error.

When communicating to localstack we need aws cli installed in the respactive container(deployment). This is because it uses aws configuration to connect to localstack. Below are the command to create and send the message to a queue

aws sqs create-queue --queue-name input
aws sqs create-queue --queue-name output
aws sqs create-queue --queue-name error
aws sqs list-queues
aws sqs send-message --queue-url https://sqs.ap-south-1.amazonaws.com/xxxxxxxx/input --message-body 'Test Message!'

Building the app

Producer Function

The producer function is a go program which creates a message with timestamp and drops into a queue input. For brevity all values have been hard coded in the code itself.

package main
​
import (
    "fmt"
    "log"
​
    "github.com/aws/aws-sdk-go/aws"
    "github.com/aws/aws-sdk-go/aws/credentials"
    "github.com/aws/aws-sdk-go/aws/session"
    "github.com/aws/aws-sdk-go/service/sqs"
)
​
func Handler(w http.ResponseWriter, r *http.Request) {​
    queueURL := "https://sqs.ap-south-1.amazonaws.com/xxxxxxxxxxxx/input"
    region := "ap-south-1"
    config := &aws.Config{
        Region:      &region,
        Credentials: credentials.NewStaticCredentials("xxxxxxxxxxxx", "xxxxxxxxxx", ""),
    }
​
    sess, err := session.NewSession(config)
    if err != nil {
        log.Panic("Error while creating session")
    }
    svc := sqs.New(sess)
​
    for i := 100; i < 200; i++ {
        msg := fmt.Sprintf("Hello Msg %v", i+1)
        _, err := svc.SendMessage(&sqs.SendMessageInput{
            DelaySeconds: aws.Int64(10),
            MessageBody:  &msg,
            QueueUrl:     &queueURL,
        })
        if err != nil {
            log.Panic("Error while writing message")
        }
    }
}

Since the go program uses SQS queue, we need to create the input queue to run the above program.

We are now ready to package this code and create a function so that we can execute it later. Following commands will create a environment, package and function. Verify that build for package succeeded before proceeding.

$ mkdir sqs && cd sqs
$ go mod init

# create a producer.go file with above code replacing the placeholder values with actual ones
$ go mod tidy
$ zip -qr sqs.zip *

$ fission env create --name goenv --image ghcr.io/fission/go-env --builder ghcr.io/fission/go-builder
$ fission package create --env goenv --src sqs.zip
$ fission fn create --name producerfunc --env goenv --pkg sqs-zip-xpoi --entrypoint Handler
$ fission package info --name sqs-zip-xpoi
Name:        sqs-zip-xpoi
Environment: go-sqs
Status:      succeeded
Build Logs:
Building in directory /usr/src/sqs-zip-xpoi-1bicov

Consumer function

The consumer function is nodejs function which takes the body of the request, appends a “Hello” and returns the resulting string.

module.exports = async function (context) {
    console.log(context.request.body);
    let obj = context.request.body;
    return {
        status: 200,
        body: "Hello "+ JSON.stringify(obj)
    };
}

Let’s create the environment and function:

fission env create --name nodeenv --image ghcr.io/fission/node-env
fission fn create --name consumerfunc --env nodeenv --code hellosqs.js

Connecting via trigger

We have both the functions ready but the connection between them is the missing glue. Let’s create a message queue trigger which will invoke the consumerfunc every time there is a message in input queue. The response will be sent to output queue and in case of consumerfunc invocation fails, the error is written to error queue.

fission mqt create  --name sqstest --function consumerfunc --mqtype aws-sqs-queue --topic input --resptopic output --mqtkind keda --errortopic error --metadata queueURL=https://sqs.ap-south-1.amazonaws.com/xxxxxxxx/input --metadata awsRegion=ap-south-1 --secret awsSecrets

Parameter list:

• queueURL - Full URL for the SQS Queue
• awsRegion - AWS Region for the SQS Queue
• secret - AWS credentials require to connect the queue e.g. below

If we are using localstack we don’t have to give secret but if we are using aws SQS we need to provide the secret, below is the example to create secret

kubectl create secret generic awsSecrets --from-env-file=./secret.yaml

and secret.yaml file should contain values which should correspond with parameter name in TriggerAuthentication.spec.secretTargetRef like

awsAccessKeyID=foo 
awsSecretAccessKey=bar

Testing it out

Let’s invoke the producer function so that the queue input gets some messages and we can see the consumer function in action.

$ fission fn test --name producerfunc
Successfully sent to input

To add authentication to your function calls, refer to our Fission Authentication guide.

There are a couple of ways you can verify that the consumerfunc is called:

• Check the logs of mqtrigger-sqs pods:

{"level":"info","ts":1602057916.444865,"caller":"app/main.go:165","msg":"message deleted"}
{"level":"info","ts":1602057917.4880567,"caller":"app/main.go:165","msg":"message deleted"}

• Go to aws SQS queue and check if messages are coming in output queue.

Introducing an error

Let’s introduce an error scenario - instead of consumer function returning a 200, you can return 400 which will cause an error:

module.exports = async function (context) {
    console.log(context.request.body);
    let obj = context.request.body;
    return {
        status: 400,
        body: "Hello "+ JSON.stringify(obj)
    };
}

Update the function with new code and invoke the producer function:

$ fission fn update --name consumerfunc --code hellosqs.js

$ fission fn test --name producerfunc
Successfully sent to input

We can verify the message in error queue as we did earlier:

• Go to aws SQS queue and check if messages are coming in error queue.