Forem: Hardeep Jethwani

VAR, LET, & CONST in JavaScript

Hardeep Jethwani — Tue, 23 Dec 2025 14:33:33 +0000

🤹‍♂️ `var`, `let`, and `const` in JavaScript

Three variables walk into a scope… and only two behave properly

If you’ve worked with JavaScript, you’ve definitely met these three:

var
let
const

They look similar.
They behave very differently.
And one of them (var) is responsible for a lot of emotional damage in production systems 😄

Let’s understand what really happens behind the scenes, without jargon overload and without falling asleep.

🧠 How JavaScript Runs Your Code (Very Important)

JavaScript doesn’t execute your code line by line immediately.
It first prepares everything, then runs it.

JavaScript runs in two phases:

1️⃣ Memory Creation Phase

The JS engine:

Scans the entire code
Allocates memory for variables & functions
Does not assign actual values yet

2️⃣ Execution Phase

Executes code line by line
Assigns values
Runs functions

This all happens inside something called an Execution Context.

🧪 `var` — The OG Troublemaker

Let’s start with an example everyone has seen:

console.log(a);
var a = 10;

Expected by beginners:

❌ Error

Given by JavaScript:

✅ undefined

Why? Because JavaScript is… forgiving.

Behind the scenes 👇

Memory Phase

a → undefined

Execution Phase

console.log(a); // undefined
a = 10;

Key takeaways about `var`

✅ Hoisted
✅ Initialized with undefined
❌ Not block-scoped
❌ Can be redeclared
❌ Easy to mess up

🚨 `var` Does Not Respect Block Scope

if (true) {
  var secret = "I should not escape";
}

console.log(secret); // 😱 It escaped

Why?

var is function-scoped
{} blocks mean nothing to it

This behavior caused real bugs in real applications, which is why let and const were introduced.

🧠 Enter `let` — The Responsible One

console.log(b);
let b = 20;

❌ Error:

ReferenceError: Cannot access 'b' before initialization

But wait… isn’t `let` hoisted?

👉 Yes, it is hoisted. Plot twist.

So why the error?

⏳ Temporal Dead Zone (TDZ) — Explained Simply

TDZ is the time between:

Memory allocation
Variable initialization

Memory Phase

b → <uninitialized>

Execution Phase

console.log(b); // ❌ TDZ error
b = 20;         // TDZ ends here

The JS engine basically says:

“I know you exist… but don’t touch me yet.”

🔐 Block Scope (Finally!)

if (true) {
  let score = 100;
}

console.log(score); // ❌ ReferenceError

Unlike var, let respects block boundaries.
Much safer. Much cleaner.

🔒 `const` — The Strict One

const pi = 3.14;
pi = 3.14159; // ❌ TypeError

Rules of const:

Must be initialized immediately
Cannot be reassigned
Block-scoped
Hoisted (with TDZ)

const x; // ❌ SyntaxError

JavaScript wants commitment here.

🤯 The Famous `const` + Object Confusion

const user = { name: "Hardeep" };

user.name = "Singh"; // ✅ Allowed
user = {};           // ❌ Not allowed

Why?

Because const means:

“The reference cannot change, not the contents.”

Think:

Address is fixed
Furniture inside can move

📊 Quick Comparison Table

Feature	var	let	const
Scope	Function	Block	Block
Hoisted	Yes	Yes	Yes
Initialized on hoisting	`undefined`	❌ TDZ	❌ TDZ
Redeclare	✅	❌	❌
Reassign	✅	✅	❌
Recommended today	❌ No	✅ Yes	✅ Yes

🧠 Behind the Scenes (Slightly Nerdy)

Internally, JavaScript maintains:

Variable Environment → var
Lexical Environment → let & const

That’s why:

var leaks scope
let and const don’t

🚀 Best Practices (Learned the Hard Way)

✅ Use const by default
✅ Use let only when reassignment is required
❌ Avoid var unless you’re working on legacy code

If JavaScript were designed today, var probably wouldn’t exist.

🎯 Final Thoughts

var → risky and outdated
let → safe and flexible
const → safest and preferred

JavaScript didn’t get weird.
We just finally understood how it works 😄

So, whether you're seeking JS advice, a good laugh, or simply a friendly chat about code and coffee preferences, I'm just a click away on these cloud-astic platforms.

LinkedIn: 🚀💼 hardeepjethwani@LinkedIn

TopMate: ☕🤝 hardeepjethwani@topmate

Instagram: 📸🌩️ hardeepjethwani@Instagram

X: 🐦☁️ hardeepjethwani@X

Soundtrack Sorcery: Extracting Hidden Harmonies from Your Videos with AWS

Hardeep Jethwani — Wed, 21 Feb 2024 18:20:23 +0000

NOTE: This is a repost of my Original Blog

🎬 Lights, camera, action! You've captured some fantastic videos, but there's a tiny twist to our story. We're not making the videos silent film stars; we're giving the soundtrack the limelight it deserves.

🌟 In this whimsical journey through the cloud, I'll show you how to take your video uploads and, with the help of AWS S3, Lambda, and AWS MediaConvert, conjure the audio right out of them. It's like pulling a rabbit out of a hat, but in our world, I'm pulling melodies out of videos! Join me for a magical adventure where your videos reveal their musical talents, and I promise you a touch of humour, a pinch of technical enchantment, and a whole lot of AWS magic. 🪄🎶

So no more waiting, Let's dive in !!

Introduction

In this blog, our main focus will be on crafting a workflow within the AWS platform, enabling users to effortlessly extract audio (MP4) from their video files (MP4). To achieve this, we'll harness the power of several key AWS services:

Amazon S3
AWS Lambda
AWS Media Convert
AWS IAM

Functional Flow

As you can see in the above workflow diagram, It explains how the video file flows and you get the desired MP4 Audio File. Below are the high-level steps of the workflow:

The user uploads the MP4 video file to an S3 Bucket, Let's name it here as video2audio-source-video-bucket
S3 Event Notification is triggered on file upload event on the bucket video2audio-source-video-bucket. Event Notification hits the desired target i.e., Lambda function (named video2AudioLambda) in this case.
The Lambda function creates a Media Convert Job with the respective Media Convert Properties.
Media Convert Job fetches the Video file from the S3 bucket from which Audio has to be extracted
Media Convert Job sends the generated audio file to the output S3 bucket that is configured in the Media Convert Properties. Let's consider the output bucket name here as video2audio-target-audio-bucket.
The audio file is available for download from the S3 bucket.

Building the system

Creating the S3 Buckets

Login to the AWS Console
Go to the S3 Service Dashboard and click on "Create bucket"
You will land on a page where you have to fill in the name of the S3 bucket as per your choice (here I have used video2audio-source-audio-bucket for bucket to be used for MP4 video files and video2audio-target-video-bucket for the bucket to be used to export the MP4 Audio).

Important Note: S3 bucket names are to be kept globally unique. In case the name is not available then you can use another name accordingly

Choose the region according to your choice leaving the rest of the details as it is and click on "Create Button"
Follow the same steps for both of the source and target buckets and the buckets will be created which you can find on the S3 dashboard.

Setting up the Lambda function

In our case, the Lambda function will be triggered by the S3 event notification on the upload of a file to the source S3 bucket.
Lambda function will make use of "Create Job" API call to AWS Media Convert service. Where Media Convert will be responsible for the Video to Audio Conversion.
So as the Lambda function has to access the Media Convert service to create a Job, We will have to create a role which has permissions to create the job. Let's create one.

Creating IAM Role for Lambda Function

Jump on to the IAM Service and them in the Roles section for creating the role.
Click on Create Role.
You will land on the IAM Role creation page which shows 3 steps:
- Selecting Trusted Entity: We are creating this role to be attached to a AWS Service i.e., Lambda here. So we will select "AWS Lambda" in trusted Entity Types. For the use case, we will select "Lambda".

Add Permissions: We will add the AWS MAnaged Policies to our role named "AWSElementalMediaConvertFullAccess" which will allow our Lambda to perform respective operations.

Name, Review & Create: In the Final stage you can add the name for your role (here video2AudioMediaConvertRole). Review the permissions and create the role.

So now as our Lambda function Role is created, we will jump back to understand further the requirements of Media Convert Properties.

Understanding the Media Convert "Create Job" API Call configuration

In the Create Job call, we need to send the configuration properties of the Media Convert Job. Configuration details for the job will be in JSON format.
Below Configuration Properties are to be set in the JSON:
- Queue ARN: The "Queue" is set to a specific AWS Elemental MediaConvert queue. This is where the job will be processed. The "Default" queue is commonly used when you don't have specific queue requirements. We will be using the Default Queue for which ARN is of format: arn:aws:mediaconvert:<AWS-Region>:<AWS-Account-ID>:queues/Default For this blog post, I have used "us-east-1" region.
- Role: The "Role" specifies the IAM role that Media Convert assumes to access the necessary resources.
- OutputGroups: This section defines the output settings. In our case, it's set to create a single "File Group" with an MP4 container, indicating that the output will be in MP4 format. Inside the "File Group," it defines the audio settings. The audio source is selected as "Audio Selector 1," and it uses AAC codec settings with a bitrate of 96,000 bits per second and a sample rate of 48,000 Hz.
- OutputGroupSettings: This section specifies the settings for the output file. It defines the destination S3 bucket where the output audio file will be saved.
- Inputs: Here, it defines the input settings, including the source video file path in our S3 bucket.
- Below JSON properties are to be used in our case.

{
        "Queue": "arn:aws:mediaconvert:us-east-1:<AWS:ACCOUNT:ID>:queues/Default",
        "UserMetadata": {},
        "Role": "arn:aws:iam::<<AWS:ACCOUNT:ID>:role/mediaConvertRole",
        "Settings": {
            "OutputGroups": [
                {
                    "Name": "File Group",
                    "Outputs": [
                        {
                            "ContainerSettings": {
                                "Container": "MP4",
                                "Mp4Settings": {},
                            },
                            "AudioDescriptions": [
                                {
                                    "AudioSourceName": "Audio Selector 1",
                                    "CodecSettings": {
                                        "Codec": "AAC",
                                        "AacSettings": {
                                            "Bitrate": 96000,
                                            "CodingMode": "CODING_MODE_2_0",
                                            "SampleRate": 48000,
                                        },
                                    },
                                }
                            ],
                        }
                    ],
                    "OutputGroupSettings": {
                        "Type": "FILE_GROUP_SETTINGS",
                        "FileGroupSettings": {
                            "Destination": "s3://"
                            + output_bucket
                            + "/"
                            + output_file_key
                        },
                    },
                }
            ],
            "Inputs": [
                {
                    "AudioSelectors": {
                        "Audio Selector 1": {"DefaultSelection": "DEFAULT"}
                    },
                    "VideoSelector": {},
                    "TimecodeSource": "ZEROBASED",
                    "FileInput": "s3://" + input_bucket + "/" + input_file_key,
                }
            ],
        },
    }

NOTE: Make sure to replace the Bucket Name, Role Name, Account ID, Region and File Name according to your usage.

Wait now you might be thinking about where this Role in the above property came from. So, as you remember, Our Media Convert Job will pull the changes from the source S3 bucket, Convert the Video to Audio and Push the Audio file to S3.
So to perform these operations, the Media Convert Job should be assigned a role with respective permissions. Let's understand the Role creation for the Media Convert Job in our case below.

Creating IAM Role for Media Convert Job

Jump on to the IAM Service and then in the Roles section to create the role.
Click on Create Role.
You will land on the IAM Role creation page which shows 3 steps:
- Selecting Trusted Entity: We are creating this role to be attached to a AWS Service i.e., Media Convert here. So we will select "MediaConvert" in trusted Entity Types. For the use case, we will select "MediaConvert".

Add Permissions: For Media Convert case, we will see that, we already have two AWS MAnaged Policies attached i.e., AmazonS3FullAccess & AmazonAPIGatewayInvokeFullAccess. These two policies are enough for our case as we just need access to the S3 bucket via Media Convert.

Name, Review & Create: In the Final stage you can add the name for your role (here mediaConvertRole). Review the permissions and create the role.

So, now that we are done with the Role creation tasks, We can move on to the task of creating our Lambda Function using Python.

Creating the Lambda Function

Go to the AWS Lambda Service in AWS Console
Click on "Create a function" button. You will land on the Lambda creation page.
Select the following options:
- Author from Scratch as we are going to write our lambda function code
- Name as video2AudioLambda
- Select Python 3.11 as the lambda runtime (You can make use of any other runtime too but the code changes will be needed accordingly)
- Expand "Change default execution role" Select "Use an existing Role" & then choose the IAM role that we created for Lambda (video2AudioMediaConvertRole).
- Click on "Create Function" and your raw Lambda function will be created.

Wait guys, the job is not yet done, the actual thrill is below !!!

We have to make use of the Python code given below. Paste it down in our Lambda console and Click on Deploy.
So this lambda function written in Python creates a mediaconvert client by making use of boto3 library. Then this client is used for creating a media conversion job using "Create Job" API call.
IMPORTANT: There is no need to hardcode the name of the Source S3 bucket here because, later on, we are going to configure the S3 Event Notification, which is then going to trigger the Lambda function. So the Event object will have all the details of the Bucket and Object that was uploaded to S3.
However, we need to hardcode the target bucket name & the target audio file name (Update the bucket name as per the name that you have used).
We have made use of the Media Convert properties that were explained in the above section and have passed the same to the create_job function call

AWS Lambda Python Code

import boto3
import os


def lambda_handler(event, context):
    # Initialize the MediaConvert client
    # Get the Endpoint URL from --> MediaConvert --> Account --> API Endpoint
    mediaconvert = boto3.client(
        "mediaconvert",
        endpoint_url="https://vasjpylpa.mediaconvert.us-east-1.amazonaws.com",
    )

    input_bucket = str(event["Records"][0]["s3"]["bucket"]["name"])
    input_file_key = str(event["Records"][0]["s3"]["object"]["key"])
    output_bucket = "video2audio-target-audio-bucket"
    output_file_key = "output-audio"

    # Create a job settings JSON
    job_settings = {
        "Queue": "arn:aws:mediaconvert:us-east-1:666541739853:queues/Default",
        "UserMetadata": {},
        "Role": "arn:aws:iam::666541739853:role/mediaConvertRole",
        "Settings": {
            "OutputGroups": [
                {
                    "Name": "File Group",
                    "Outputs": [
                        {
                            "ContainerSettings": {
                                "Container": "MP4",
                                "Mp4Settings": {},
                            },
                            "AudioDescriptions": [
                                {
                                    "AudioSourceName": "Audio Selector 1",
                                    "CodecSettings": {
                                        "Codec": "AAC",
                                        "AacSettings": {
                                            "Bitrate": 96000,
                                            "CodingMode": "CODING_MODE_2_0",
                                            "SampleRate": 48000,
                                        },
                                    },
                                }
                            ],
                        }
                    ],
                    "OutputGroupSettings": {
                        "Type": "FILE_GROUP_SETTINGS",
                        "FileGroupSettings": {
                            "Destination": "s3://"
                            + output_bucket
                            + "/"
                            + output_file_key
                        },
                    },
                }
            ],
            "Inputs": [
                {
                    "AudioSelectors": {
                        "Audio Selector 1": {"DefaultSelection": "DEFAULT"}
                    },
                    "VideoSelector": {},
                    "TimecodeSource": "ZEROBASED",
                    "FileInput": "s3://" + input_bucket + "/" + input_file_key,
                }
            ],
        },
    }
    # Start the MediaConvert job
    response = mediaconvert.create_job(**job_settings)

    print(str(response))

    return {"statusCode": 200, "body": "MediaConvert job started successfully."}

You have to copy the above code and paste it to the Lambda console and then click on Deploy!!

In above Python code you might have noticed that we have made use of an endpoint URL (https://vasjpylpa.mediaconvert.us-east-1.amazonaws.com)to create the mediaConvert Client. You can get that endpoint URL by going into your Media Convert Service in AWS Console at path: MediaConvert --> Account --> API Endpoint

Configuring S3 Event Notification

Go to AWS S3 Console
Click on your bucket (video2audio-source-video-bucket). Then go to "Properties" section of the same.
On Scrolling down, you will find the section for "Event Notification". You have to click on "Create Event Notification"

You will land on a page to fill in the details for S3 Event trigger action and the target.
You can name your event and then select the format of the file that we want to trigger our Audio Conversion action on. So here we are using ".mp4" as the source file format.
In the Event Types, Just check on the "All Object Creation Events", as we have to trigger this conversion on every file creation/updation event
Scroll down to the bottom to fill in the Destination details !! In our case it is a lambda function named "video2AudioLambda" (You can also choose to fill the ARN of the lambda function)
And then Just click on the save changes.

Woohoooo we have finally completed the Build phase !!! Now it is the time to test our design....

Testing the setup

We have to upload a MP4 video file in the source bucket (here video2audio-source-video-bucket)
Then in a few seconds, you can check your target bucket (here video2audio-target-audio-bucket) And you will finally see an MP4 Audio file over there.

Advanced Learning Capsule points

Checking Lambda Executions: In case you want to check the Lambda Execution, you will have to first Assign an IAM policy to your Lambda Role for CloudWatch Logs Access. Which will then allow your Lambda Function to publish logs to your CloudWatch Log Dashboard. You can access the logs via Going into the Log Group and checking for the LogGroup "/aws/lambda/<your-lambda-function-name>"

Checking Job Submissions in Media Convert Service:
- Go to the Media Convert Service on AWS Console.
- Click on the Jobs option in the Menu on the Left.
- You will find all of the Job Submissions and you can check the status of each respective job easily.

As we conclude this journey into the fascinating realm of audio extraction from video, I hope you've not only gained valuable insights but also a newfound appreciation for the versatility of AWS. The possibilities are endless when you combine technology with creativity.

Thank you for being a part of this adventure. Until next time, happy cloud computing!!

If you have any questions, ideas, or experiences you'd like to share, I'm all ears. Let's keep the conversation going in the comments section below. And remember, this is just the beginning; there's a world of innovation waiting for you in the cloud. Stay curious, keep exploring, and keep making technology work for you. Follow me on social media, where I promise to share cloud wisdom with a side of chuckles:

LinkedIn: Connect with me on LinkedIn, where my cloud prowess is only rivalled by my talent for finding the perfect GIF for every situation. 🚀💼 hardeepjethwani@LinkedIn
TopMate: Looking for a fellow cloud aficionado to share a virtual coffee with or brainstorm your next AWS masterpiece? Find me on TopMate! Because let's face it, cloud enthusiasts need to stick together. ☕🤝 hardeepjethwani@topmate
Instagram: For behind-the-scenes glimpses of my cloud adventures and occasional 'AWS Gone Wild' stories that even AWS engineers find amusing. 📸🌩️ hardeepjethwani@Instagram
X: Join the cloud conversation on Twitter, where I drop cloud knowledge and quirky cloud memes faster than you can say 'Elastic Beanstalk.' 🐦☁️ hardeepjethwani@X

So, whether you're seeking cloud advice, a good laugh, or simply a friendly chat about cloud and coffee preferences, I'm just a click away on these cloud-tastic platforms. See you in the cloudisphere, fellow cloud builders!" 🌍☁️😄

Want to support my cloud adventures and keep the coffee flowing? Feel free to buy me a virtual coffee. After all, coffee is the secret sauce behind every successful cloud deployment. ☕🙌

The IT Comedy: An Amusing Guide to Network Ports on Linux and Beyond !

Hardeep Jethwani — Sat, 14 Oct 2023 11:08:46 +0000

Disclaimer: This blog is a repost of my original blog which you can find at - https://blog.hardeepjethwani.com/the-it-comedy-an-amusing-guide-to-network-ports-on-linux-and-beyond

Introduction:

In the quirky realm of information technology, network ports are like the secret passages in a high-tech castle. Understanding which ones are the life of the party is essential for system administrators, network comedians, and anyone who wants to add a bit of fun to their IT game. This guide will provide you with insights into the wackiest network ports, their significance (or lack thereof), and best practices for keeping the network circus under control.

Section 1: Understanding Network Ports

Picture network ports as doors with numbers—some are heavily guarded, while others are just wide open. They're grouped into three categories, sort of like a circus act:

Well-Known Ports (0-1023): These are the rock stars, headlining the show with their fame and fortune. Everybody knows their moves.
Registered Ports (1024-49151): These are the middle-aged port numbers. They've got some recognition, but they're not quite "The Beatles."
Dynamic or Private Ports (49152-65535): These are like underground clubs. Not many know about them, but they have their own cult following.

Section 2: Common Network Ports

Here are some of the network ports that are always in the spotlight:

Port 22 (SSH): This is the VIP entrance to your server. Only the cool kids with the right key can get in.
Port 80 (HTTP): It's like the highway to your website, where everyone's welcome.
Port 443 (HTTPS): This is the secure version of the highway, with a secret handshake (SSL/TLS).
Port 21 (FTP): It's the dressing room for your files, where they prepare to perform.
Port 25 (SMTP): The postman's office, where emails are sent on their merry way.
Port 3306 (MySQL): The backstage of your database, where the magic happens.
Port 23 (Telnet): It's the vintage telephone booth of IT, but use it wisely; it has a few holes.
Port 67 (DHCP): This is where IP addresses are handed out like party favors.
Port 53 (DNS): The directory service for the web. It translates names to numbers like a techy phone book.
Port 161 (SNMP): The watchful eye in the control room, keeping an eye on all the IT antics.
Port 68 (DHCP): The place where devices ask for tickets to the network party.
Port 110 (POP3): The inbox of your email server, where your messages await.
Port 143 (IMAP): Another email stage, where messages are rehearsing for the big performance.
Port 67 (DHCP): The backstage chaos where devices get assigned to the network show.
Port 69 (TFTP): The quickest file transfer act in town, for those who like it fast.

Each of these ports has its own gig, and they're at the heart of many IT operations.

Section 3: Security Considerations

Securing network ports is like putting a bouncer at the club's entrance. You want to keep the party safe:

Firewall Configuration: Think of it as the guest list for the VIP section. Only allow the right people (or packets) inside.
Access Control: Imagine a velvet rope at the door. Not everyone gets to cross it.
Intrusion Prevention: It's like a security team with a net, ready to catch any misbehaving clowns.
Least Privilege: Only let performers backstage who have a legitimate role in the show.

Section 4: Less Common But Valuable Ports

While the common ports are busy in the limelight, some lesser-known ports play their own unique tune:

ICMP (Ping): ICMP (I Can Make People) is the friendliest act in the networking world. It's all about saying hello and checking if someone's home.
SFTP (Port 22): Secure File Transfer Protocol, with the ticket booth conveniently located at the SSH (Secret Side Hallway) entrance.

Section 5: Tools for Port Scanning

Port scanning tools, like Nmap, are like the x-ray vision of the IT universe. Use them to see through the doors and check if everything's in order.

Section 6: Case Studies

Let's look at a few case studies to see how these ports bring laughter (or sometimes chaos) to real-world IT parties:

Case Study 1 - ICMP (Ping): ICMP is like a friendly neighbour who knocks on the door to see if you're home. A bit nosy, but well-intentioned.
Case Study 2 - SFTP (Port 22): Secure File Transfer Protocol is the bouncer at the secret club within the club. Only the chosen ones get through.

Section 7: Conclusion

Understanding network ports is like being a circus ringleader, keeping a show with many acts running smoothly. The most useful network ports, like SSH (port 22), HTTP (port 80), and HTTPS (port 443), are the circus stars, but don't forget the lesser-known ones—they have their unique charm.

By following best practices, securing the party with bouncers (firewalls), and regularly checking for misbehaving clowns (port scanning), you'll ensure that your network circus is the talk of the town.

Thank you for joining me in a thrilling Circus Show of N/W Ports. Happy Learning !! 😄🏰

Do you have more burning questions or just need a daily dose of tech humor? Follow me on social media, where I promise to share cloud wisdom with a side of chuckles:

LinkedIn: Connect with me on LinkedIn, where my cloud prowess is only rivalled by my talent for finding the perfect GIF for every situation. 🚀💼 hardeepjethwani@LinkedIn
TopMate: Looking for a fellow cloud aficionado to share a virtual coffee with or brainstorm your next AWS masterpiece? Find me on TopMate! Because let's face it, cloud enthusiasts need to stick together. ☕🤝 hardeepjethwani@topmate
Instagram: For behind-the-scenes glimpses of my cloud adventures and occasional 'AWS Gone Wild' stories that even AWS engineers find amusing. 📸🌩️ hardeepjethwani@Instagram
X: Join the cloud conversation on Twitter, where I drop cloud knowledge and quirky cloud memes faster than you can say 'Elastic Beanstalk.' 🐦☁️ hardeepjethwani@X

So, whether you're seeking cloud advice, a good laugh, or simply a friendly chat about cloud formations and coffee preferences, I'm just a click away on these cloud-tastic platforms. See you in the cloudisphere, fellow cloud builders!" 🌍☁️😄

Turning Text into Talk on AWS: The Polly-Phonic Symphony of S3, Lambda and Amazon Polly

Hardeep Jethwani — Mon, 09 Oct 2023 05:47:15 +0000

🎉 Dear readers, welcome to the grand orchestration of the digital age, where we'll take you on a captivating journey from the realm of text to the symphonic world of spoken words. In this technological masterpiece, we'll explore how the dynamic quartet of AWS S3, Lambda, and Amazon Polly 📦🔗🧬🗣️ comes together to turn mere text into audio. So, get ready to be dazzled as we unravel 'Turning Text into Talk on AWS: The Polly-Phonic Symphony of S3, Lambda, and Amazon Polly.' 🎶 It's a show you won't wish to miss! 🚀 Happy Learning !!

So Let's dive into the practical world now !!

Introduction

In this blog, we are going to design a workflow that will be able to convert the text file of any transcript and convert them into an Audio MP3 file automatically without any manual Intervention.

Functional Flow

If you can see in the above workflow diagram, It explains how the file flows and you get the desired MP3 File. Below are the high-level steps of the workflow:

The file is uploaded to an S3 Bucket, Let's name it here as text2talk-source-transcript-bucket
S3 Event Notification is triggered which is configured for the bucket text2talk-source-transcript-bucket.
The Target of the S3 Event Notification is the Lambda function (let's name it as "text2talk" which we will use to convert the text transcript file uploaded to S3 bucket text2audio-source-transcript-bucket
The lambda function will fetch the text from the transcript file and send the content to Amazon Polly which will send back the data converted in form of an Audio file data.
The audio file will finally be uploaded to another S3 bucket. Let's name it here as text2talk-target-audio-bucket.

Building the system

-> Creating the S3 Buckets

Login to the AWS console
Go to the S3 Service Dashboard and click on "Create bucket"
You will land on a page where you have to fill in the name of the S3 bucket as per your choice (here I have used text2talk-source-transcript-bucket for bucket to be used for transcript text files and text2talk-target-audio-bucket for bucket to be used export the Audio).

Important Note: S3 bucket names are to be kept globally unique. In case the name is not available then you can use another name accordingly
Choose the region according to your choice leaving the rest of the details as it is and click on "Create Button"
Follow the same steps for both of the source and target buckets and the buckets will be created which you can find on the S3 dashboard.

-> Setting up the Lambda Function

In our case, the lambda function will be accessing the S3 bucket to pull the transcript file and push the Audio file too !!
Also, the Lambda function will be making use of "Speech Synthesize" provided by Amazon Polly.
So In this case, Our Lambda Function should have the respective permissions to access the S3 bucket and Polly API calls !!
So we will create an IAM role first which is then to be assigned to the Lambda function later.

-> Creating IAM Role**

Jump on to the IAM Service and them in the Roles section for creating the role.
Click on Create Role.
You will land on the IAM Role creation page which shows 3 steps:
- Selecting Trusted Identity: We are creating this role to be attached to a AWS Service i.e., Lambda here. So we will select "AWS Lambda" in trusted Entity Types. For the use case, we will select "Lambda".
- Add Permissions: We will add the AWS MAnaged Policies to our role named "AmazonPollyReadOnlyAccess" & "AmazonS3FullAccess" which will allow our Lambda to perform respective operations.
- Name, Review & Create: In the Final stage you can add the name for your role (here text2talkRole). Review the permissions and create the role.

So now that we have created the IAM Role as per our needs we will jump on creating our Lambda function finally.

-> Creating the Lambda Function

Go to the AWS Lambda Service in AWS Console
Click on "Create a function" button. You will land to the Lambda creation page.
Select the following options:
- Author from Scratch as we are going to write our lambda function code
- Name as text2talk
- Select Python 3.11 as the lambda runtime (You can make us of any other runtime too but the code changes will be needed accordingly)
- Expand "Change default execution role" Select "Use an existing Role" & then choose the IAM role that we created.
- Click on "Create Function" and your raw Lamda function will be created.

Wait guys, the job is not yet done, the actual thrill is below !!!

We have to make use of the Python code below paste it down in our Lambda console and Click on Deploy.
So this lambda function written in Python creates an S3 client by making use of boto3 library. And then the S3 client is used for Pulling the file from our source S3 bucket.
IMPORTANT: There is no need to hardcode the name of the Source S3 bucket here because, later on, we are going to configure the S3 Event Notification, which is then going to trigger the Lambda function. So the Event object will have all the details of the Bucket and Object that was uploaded to S3.
However, we need to hardcode the target bucket name (Update the bucket name as per the name that you have used).
This Python function also creates a client object for operating with polly (polly_client). We are making use of synthesize_speech call for Polly where we are passing the audio format, text format and the Voice ID Parameters
We have passed the Voice ID parameter as "Salli" but you can play around with different voices and refer to Amazon Polly Voice List Blog.

AWS Lambda Python Code

import json
import boto3
import datetime

# Get the current timestamp
current_time = datetime.datetime.now()

# Format the timestamp as "ddmmyy"
timestamp = current_time.strftime("%d%m%y")

# Initialize AWS clients
s3_client = boto3.client('s3')
polly_client = boto3.client('polly')

def lambda_handler(event, context):
    # Define the source and destination S3 bucket and file names
    source_bucket = str(event["Records"][0]['s3']['bucket']['name']) #These are the details received from the S3 Event and we are gathering bucket name and File name of the same
    source_file_key = str(event["Records"][0]['s3']['object']['key'])
    destination_bucket = 'text2talk-target-audio-bucket' ## Update the target bucket name accordingly as per bucket name in your account
    destination_file_key = f"{timestamp}-audio.mp3"

    # Fetch the text content from the source S3 bucket
    try:
        response = s3_client.get_object(Bucket=source_bucket, Key=source_file_key)
        text = response['Body'].read().decode('utf-8')
    except Exception as e:
        print(str(e))
        return {
            'statusCode': 500,
            'body': f'Error fetching text from S3: {str(e)}'
        }

    # Use Amazon Polly to synthesize speech from the text
    try:
        response = polly_client.synthesize_speech(
            OutputFormat='mp3',
            Text=text,
            VoiceId='Salli'  # You can choose a different voice IDs too
        )
        audio_data = response['AudioStream'].read()
    except Exception as e:
        print(str(e))
        return {
            'statusCode': 500,
            'body': f'Error synthesizing speech with Polly: {str(e)}'
        }

    # Upload the MP3 audio to the destination S3 bucket
    try:
        s3_client.put_object(Bucket=destination_bucket, Key=destination_file_key, Body=audio_data)
    except Exception as e:
        print(str(e))
        return {
            'statusCode': 500,
            'body': f'Error uploading MP3 to S3: {str(e)}'
        }
    print("success")    

    return {
        'statusCode': 200,
        'body': f'Successfully converted and saved text to MP3: s3://{destination_bucket}/{destination_file_key}'
    }

You have to copy the above code and paste it to the Lambda console and then click on Deploy!!

So now what, We have our Lambda function ready !!

Now we will move to our final step !! i.e, configuring S3 Event Notification on our source S3 bucket !!

-> Configuring S3 Event Notification

Go to AWS S3 Console
Click on your bucket (here text2talk-source-transcript-bucket). And then go to "Properties" section of the same.
On Scrolling down, you will find the section for "Event Notification". You have to click on "Create Event Notification"
You will land on a page to fill in the details for S3 Event trigger action and the target.
You can name your event and then select the format of the file that we want to trigger our Audio Conversion action on. So here we are using ".txt" as the source file format.
In the Event Types, Just check on the "All Object Creation Events", as we have to trigger this conversion on every file creation/updation event
Scroll down to the bottom to fill in the Destination details !! In our case it is a lambda function named "text2talk" (You can also choose to fill the ARN of the lambda function)
And then Just click on the save changes

Woohoooo we have finally completed the Build phase !!! Now it is the time to test our design....

Testing the setup !!!!

You have to just upload a test file in the source bucket (here text2talk-source-transcript-bucket) (I have made sample text which you can find HERE on GitHub !!
Then in a few seconds, you can check your target bucket (here ) Andddddd you will finally see an Audio file over there !! (You can find my results HERE on GitHub)

So Finally we were able to make it up !!! Congratulations !!!

Thank you for joining me on this Polly-Phonic conversion journey, where reality is stranger than fiction, and the only drama involves coding conundrums. Happy cloud building, and may your infrastructure always stay drama-free! ☁️😄🏰

Do you have more burning questions or just need a daily dose of cloud-related humor? Follow me on social media, where I promise to share cloud wisdom with a side of chuckles:

LinkedIn: Connect with me on LinkedIn, where my cloud prowess is only rivalled by my talent for finding the perfect GIF for every situation. 🚀💼 hardeepjethwani@LinkedIn
TopMate: Looking for a fellow cloud aficionado to share a virtual coffee with or brainstorm your next AWS masterpiece? Find me on TopMate! Because let's face it, cloud enthusiasts need to stick together. ☕🤝 hardeepjethwani@topmate
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Forem: Hardeep Jethwani

VAR, LET, & CONST in JavaScript

🤹‍♂️ var, let, and const in JavaScript

Three variables walk into a scope… and only two behave properly

🧠 How JavaScript Runs Your Code (Very Important)

JavaScript runs in two phases:

1️⃣ Memory Creation Phase

2️⃣ Execution Phase

🧪 var — The OG Troublemaker

Expected by beginners:

Given by JavaScript:

Behind the scenes 👇

Key takeaways about var

🚨 var Does Not Respect Block Scope

🧠 Enter let — The Responsible One

But wait… isn’t let hoisted?

⏳ Temporal Dead Zone (TDZ) — Explained Simply

Memory Phase

Execution Phase

🔐 Block Scope (Finally!)

🔒 const — The Strict One

🤯 The Famous const + Object Confusion

📊 Quick Comparison Table

🧠 Behind the Scenes (Slightly Nerdy)

🚀 Best Practices (Learned the Hard Way)

🎯 Final Thoughts

Soundtrack Sorcery: Extracting Hidden Harmonies from Your Videos with AWS

Introduction

Functional Flow

Building the system

Creating the S3 Buckets

Setting up the Lambda function

Creating IAM Role for Lambda Function

Understanding the Media Convert "Create Job" API Call configuration

Creating IAM Role for Media Convert Job

Creating the Lambda Function

Configuring S3 Event Notification

Testing the setup

Advanced Learning Capsule points

Thank you for being a part of this adventure. Until next time, happy cloud computing!!

The IT Comedy: An Amusing Guide to Network Ports on Linux and Beyond !

Thank you for joining me in a thrilling Circus Show of N/W Ports. Happy Learning !! 😄🏰

Turning Text into Talk on AWS: The Polly-Phonic Symphony of S3, Lambda and Amazon Polly

Introduction

Functional Flow

Building the system

-> Creating the S3 Buckets

-> Setting up the Lambda Function

-> Creating IAM Role**

-> Creating the Lambda Function

-> Configuring S3 Event Notification

Testing the setup !!!!

Thank you for joining me on this Polly-Phonic conversion journey, where reality is stranger than fiction, and the only drama involves coding conundrums. Happy cloud building, and may your infrastructure always stay drama-free! ☁️😄🏰

🤹‍♂️ `var`, `let`, and `const` in JavaScript

🧪 `var` — The OG Troublemaker

Key takeaways about `var`

🚨 `var` Does Not Respect Block Scope

🧠 Enter `let` — The Responsible One

But wait… isn’t `let` hoisted?

🔒 `const` — The Strict One

🤯 The Famous `const` + Object Confusion