Creating an AWS Lambda Function for Scheduling

Introduction

AWS Lambda is a fully-managed, highly-scalable serverless function service.

In this Lab Step, you will create a Lambda function that fetches a web page and inspects the contents.

Instructions

1. In the AWS Management Console search bar, enter Lambda, and click the Lambda result under Services:

2. Click Create function:

3. In the Create function form, ensure Author from scratch is selected:

4. In the Basic information section of the form, in the Function name field, enter lab-function:

5. In the Runtime drop-down, select Python 3.8:

Runtimes are programming languages that are used to execute function code. Lambda supports a number of different runtimes, the most popular are Python and NodeJS. In this Lab Step, you will implement your function in Python.

6. Click Change default execution role:

7. Select Use an existing role:

8. In the Existing role drop-down, select lambda_basic_execution:

This role has been pre-populated for this Lab. It allows the function to create logs in Amazon CloudWatch. In a non-lab environement, when creating a Lambda function, you will create your own role beforehand or use an appropriate pre-existing role.

9. To create your function, scroll to the bottom and click Create function:

 10. In the Code source section, double click the lambda_function.py file, and replace the code in the editor textbox with the following:

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from urllib.request import urlopen
URL = 'https://cloudacademy.com'
TEXT = 'AWS'
def lambda_handler(event, context):
    print('Event: %s' % event)
    t = event.get('time') or "?"
    with urlopen(URL) as u:
        output = u.read().decode('utf-8')
        if output:
            if TEXT in output:
                return "SUCCESS at %s" % t
    print('%s not found in %s at %s' % (TEXT, URL, t))
    return "FAILURE"

This code fetches the contents of the front page of the CloudAcademy website. If the page contains the text "AWS" it returns "SUCCESS" along with a timestamp.

In this lab the return value is not important, because the goal of the Lab is to run the function on a schedule. When you implement Lambda functions you can use the return value to pass data or a result back to the system that called the function.

11. To deploy your function, at the top of the Code source section, click Deploy:

You will see a notification that your function has been deployed:

Summary

In this Lab Step, you created a Lambda function and you added a simple example implementation of website monitoring to your function.