Implementing Serverless Architecture with AWS Lambda and SQS Triggers

Module 9: Lambda Assignment

Problem Statement: You work for XYZ Corporation. Your corporation wants to launch a new web-based application and they do not want their servers to be running all the time. It should also be managed by AWS. Implement suitable solutions.

Tasks To Be Performed:

1. Create a sample Python Lambda function.
2. Set the Lambda Trigger as SQS and send a message to test invocations.

Setting Up and Testing an AWS Lambda Triggered by SQS

1. I create an SQS queue. Using the steps from [[Assignment 4 – SQS And SES_Module8_AWS Weekday BC = 2301080808#|Assignment 4 – SQS And SES]], I create an SQS named lambdaSQS with defaults.
2. Create the Python Lambda Function
   • I open my preferred code editor.
   • I create a new Python file and write the following code:

def lambda_handler(event, context):
    # Process the SQS messages
    for record in event['Records']:
        message = record['body']
        print(f"Received message: {message}")
 
    return {
        'statusCode': 200,
        'body': 'Processed the messages successfully!'
    }

3. Deploying the Lambda Function on AWS

   • I log into my AWS account.
   • I navigate to the AWS Lambda dashboard.
   • I click on “Create function”.
   • I provide a name for my function myPythonFunction.
   • I choose Python 3.11 for the runtime.
   • Clicked “Create function”
   • I copy and paste the Python code from step 1 into the Lambda editor.
   • I click “Save” to save my function.

4. Setting up the Lambda Trigger as SQS

   • In the AWS Lambda dashboard, I find the “Designer” section for my function.
   • I click on “Add trigger”.
     
   • I choose “SQS” from the list of available services.
   • I select the SQS queue I want to use.
     
   • Made sure “Activate trigger” was checked
   • Left default configurations.
   • Clicked “Add”.

Failure

An error occurred when creating the trigger: The provided execution role does not have permissions to call ReceiveMessage on SQS

Solution

For my function myPythonFunction, I’ll update the attached role myPythonFunction-role-me7z96sv in the IAM console by adding the necessary permissions.

1. I locate the myPythonFunction-role-me7z96sv role.
   • On the IAM dashboard, I select “Roles” from the left-hand navigation pane.
   • I find and click on myPythonFunction-role-me7z96sv (role attached to my function).
2. I attach the necessary permissions.
   • On the role details page, I click on the “Attach policies” button.
   • In the search box, I can:
     • Search for the AWSLambdaSQSQueueExecutionRole managed policy, which provides permissions for a Lambda function to interact with SQS.

Successfully moved on to the next step

Edited the trigger made sure “Activate trigger” was checked

• Testing the Lambda Function

  • I navigate to the SQS dashboard.
  • I select the queue I’ve set as a trigger lambdaSQS.
  • I click on the “Send and receive messages” button.
  • I send a sample message to the queue.
    
  • I wait for a moment as AWS Lambda automatically triggers upon receiving the message in SQS.
  • I then navigate to the CloudWatch logs associated with my Lambda function.
    
  • I confirm the print statement from my Python code displays the message I sent to the queue.

Success