The Notification that Python Built

A Beginner’s Guide to Using Python to Create a Standard SQS Queue to Receive Messages with a Lambda Function Triggered by API Gateway

Published in

Women in Technology

7 min readMay 30, 2023

Hello again! Today, I wanted to provide a walk-through creating a system that can track customer orders as well as send status notifications. I mean, who doesn’t love that email letting you know the status of your order? Our objective will be to build a system utilizing AWS services with Python. Are you up for the challenge? If so, let’s go…

A little background //

SQS (Amazon Simple Queue Service) is a fully managed AWS Service. SQS allows you the ability to send, store, and receive messages between software components at any volume, without losing messages or requiring other services to be available.

Objectives //

Create a Standard SQS Queue using Python
Create a Lambda function in the console with a Python 3.7 or higher runtime
Modify the Lambda to send a message to the SQS queue
Create an API Gateway HTTP API type trigger
Test the trigger to verify the message was sent

To follow along with this project you will need //

Access to AWS
An Configured AWS Cloud9 with AWS CLI & Boto3
An Optional GitHub Account
Attention to Details

Creating an SQS (Simple Queue Service) //

Our script we will be creating a Standard queue vs a FIFO (First-In-First-Out). If you need a FIFO queue you will need to adjust the code to specifiy FifoQueue attribute.

To create our SQS we will start in AWS Cloud9 on a New Branch:

Create a New Python File from Template

Import the Boto3 SDK
(Boto3 will allow us to interact with AWS Services through Python code.)
Obtain the service resource
Create the Queue
print the response

#This code will create a standard SQS
import boto3

#Create a low-level SQS Client
sqs = boto3.client('sqs', region_name = 'us-east-1')

#Creating the Queue
response = sqs.create_queue(
    QueueName= 'fosterwk15')
print(response)

Save as Create_SQS.py and then Run

We can verify on AWS console by searching for Amazon SQS🠆Queues.

Create a Lambda Function //

With our successful queue created, we can now create our Lambda function which will actually send the message to our queue. Navigate to Lambda from the AWS console.

Select Create function

Select Author from scratch
Add Function Name
Select Runtime Python 3.8
Click Create a function

With our successful Lambda function created, we need to ensure our Lambda Execution role has appropriate permissions. Navigate to the Configuration Tab on your success screen.

Select the highlighted role name, which will open up IAM in a new window
Select Add permissions
Search for SQSFullAccess
(Note: granting full access for demo only)

Back on our Lambda success screen, we need to add our SQS as a destination.

Select Add destination

Change Destination Type to SQS queue
Change Destination to the SQS queue we created
Click Save

Next, we will continue to our third objective. You are doing great!!

Modify the Lambda to send a message to the SQS queue //

Remaining on our Lambda screen

Select Code Tab to Edit
Add the code below
(Update the QueueURL to your specific URL which you can find on your SQS Queue Detail)
Click Deploy to save all changes

import boto3 
import json

from datetime import datetime

def lambda_handler(event, context):
    # creating sqs client
    sqs = boto3.client('sqs')  
    # using the now() function to get a datetime object containing current date and time.
    now = datetime.now() 
    # using datetime.strftime() function to create a string representing
    # the current time
    time_date = now.strftime("%H:%M:%S %m/%d/%Y")  
   
     
    # sending the message to the sqs queue
    sqs.send_message(  
        # sqs queue url: found in SQS Details
        QueueUrl = 'https://sqs.us-east-1.amazonaws.com/796344786736/fosterwk15', 
        MessageBody = time_date)
    return {
        'statusCode': '200',
        'body': json.dumps('Order_Processed')
    }

Click Test to configure a test event
Name Event
Keep on Private
Select Template: apigateway-aws-proxy

Click Save
Select Test

Navigate to SQS Dashboard for another way to confirm that our Lambda function can successfully send a message to the SQS queue.

Select SQS Queue we created
Select Send and receive messages

Select Poll Messages
This will take a few minutes to populate, but if we are successful we should see a message appear at the bottom of the screen.

Select Blue Highlighted Message
Select Body

Successful Test!! The Body is showing the Time in UTC. To formulate to your current time zone, you can utilize a convertor.

Let’s stretch before we complete the last two objectives. Remember when coding, case sensitivity can cause errors. Make sure to check your puctuation as well. Believe it or not a little space can cause a bit of a headache.

When you are ready, let’s wrap up this walk-through and finish strong!

Create an API Gateway HTTP API type trigger //

Let’s add an API Gateway HTTP API type trigger to our Lambda functon. Navigate back to the Lambda function we carefully created. Just like we added the destination to our function, we will now choose Add trigger.

Choose API Gateway from dropdown
Select Create a new API
Select HTTP API
Configure Security to Open
Select Add

We now have a successful API Gateway as a Trigger and Amazon SQS as a destination

Our Lambda function is now connected to the API Gateway and we can use it to send messages to our queue. Take a deep breath, we are moments away from completing this walk-through.

Test the API Gateway HTTP API type trigger //

To test our trigger, we don’t even have to leave our Lambda function. At the bottom of the screen you should be able to select Triggers from the left-hand menu and then go to the Configuration tab.

Select the highlighted blue https address

You should see a new internet window open with our message:

Additionally, we can verify by polling our SQS queue one final time.

Select SQS Queue
Select Send and receive messages

Select Poll for messages

High Fives all around! Together, we created the foundations to be able to send an “Order Processed” message. Just think of all the possiblities we could build upon. I encourage you to continue to push yourself with new challenges. I hope you join me on my next one!

Tips //

Commit any new or updated codes to your GitHub
(Merge and delete your branch)
Delete your SQS
Delete Lambda function

Helpful Resources //

Amazon SQS queue types

Unlimited Throughput - Standard queues support a nearly unlimited number of API calls per second, per API action (…

docs.aws.amazon.com

create_queue — Boto3 1.26.139 documentation

Client / create_queue Creates a new standard or FIFO queue. You can pass one or more attributes in the request. Keep…

boto3.amazonaws.com

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