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Lambda Function In AWS

In this article, we will discuss the lambda function in AWS.

Serverless Computing Model

The serverless computing model allows you to run your code without managing any server.

What Is A Lambda Function?

Consider the following scenario - There is an organization where employees use a software application to mark their attendance. The software application has a button Mark attendance

It takes 10 seconds to mark attendance for a single employee. For 50 employees, it takes 500 seconds per day to mark their attendance.

If the organization manages a server that works 8 hours a day and 5 days a week, then the organization pays for 8 hours daily (and 40 hours per week). But the actual time requirement is 500 seconds.

To overcome this issue, AWS has come up with a lambda function. In the lambda function, you write a code and invoke it. So, you pay the price only when you invoke the function.

So, lambda reduces the overhead of managing a server and reduces the cost.

How To Create A Lambda Function In AWS?

For creating a lambda function, we will work on the following steps: -

Verify emails in Simple Email Service (SES)
Create a lambda function
Write code to send an email
Change the policy
Invoke the function

Let us get started.

Verify Emails In Simple Email Service (SES)

First, verify the sender and recipient email id in Amazon SES. You can refer to this article.

Create A Lambda Function

For creating the lambda function, search the word lambda in the search box. Click on the Lambda service in the search result.

Picture showing the lambda function in AWS console search result

Click to Enlarge

In the lambda function screen, click on the Create function button.

Picture showing the Create function button for creating the new lambda function

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A screen will appear to enter the following information: -

Function name
Runtime
Architecture
Execution role

Please note that you can either create a new role or use the existing role. If you choose to create a new role then AWS automatically creates a new role for you at the time of function creation.

Picture showing the create lambda function screen in AWS console

Click to Enlarge

Write Code To Send An Email

Once the function is created, go to the function, and paste the following code in the Code source section.

var aws = require('aws-sdk');

aws.config.getCredentials(function (err) {
    if (err) console.log(err.stack);        
    else {
        //console.log("Access key:", aws.config.credentials.accessKeyId);
    }
});

var ses = new aws.SES({
    region: 'ap-south-1'
});

exports.handler = function () {
    //console.log("Incoming: ", event);
    var eParams = {
        Destination: {
            ToAddresses: ["SESverifiedemail@gmail.com"]
        },
        Message: {
            Body: {
                Text: {
                    Data: "Lambda is working"
                }               
            },
            Subject: {
                Data: "Mail From SES"
            }

        },
        Source: "SESverifiedemail@gmail.com"
    };
    console.log('===Sending Email====');
    var email = ses.sendEmail(eParams, function (err, data) {

        //console.log(eParams);
        if (err) console.log(err);
        else {
            console.log('===Email Sent====');
            //context.succeed(event);
        }
    });
};


exports.handler();

Picture showing the screen to write code for lambda function

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Finally, click on the Deploy button to deploy your code.

Picture showing the Deploy button for deploying the code

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Change The Policy

To change the policy, you must select the default execution role of the lambda function and edit the policy. Post that, perform these 2 actions and save the policy.

Add SES:SendEmail and SES:SendRawEmail inside the Action
Set the value of Resource to *

Picture showing the screen to change the permissions in the lambda role

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Invoke The Function

To invoke the function, go to the Test tab of the lambda function.

Picture showing the screen to invoke the lambda functions

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Click on the Test button.

Picture showing the output of the lambda function when the function is invoked

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You will receive an email.

Picture showing the email recieved from lambda function

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What Is The Maximum Execution Time Of Lambda Function?

15 mins

Posted By -	Karan Gupta

Posted On -	Thursday, January 6, 2022

Updated On -	Friday, September 16, 2022

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