AWS Lambda Function: How it Works & How to Create It?

In this blog, we’ll explore the complexities of AWS Lambda, the serverless computing offering that enables you to execute your code without the hassle of server management or provisioning. Grasping what is AWS Lambda and its ins and outs are pivotal for professionals eager to enhance their skills or pivot their careers in cloud computing.

Unveiling AWS Lambda: Introduction

A serverless computing service, AWS Lambda is offered by Amazon Web Services (AWS). It enables you to run code without worrying about the underlying infrastructure, thereby freeing developers from the hassle of managing servers. AWS Lambda automatically scales your applications in response to the volume of incoming traffic, adjusts its capacity, and only charges for the compute time consumed.

When Should You Opt for AWS Lambda?

The decision to use AWS Lambda largely depends on the kind of application or service you’re working on. Ideal scenarios for its implementation include:

  • Event-Driven Architecture: AWS Lambda shines in event-driven architectures, where it can handle individual incoming requests like file uploads or updates.
  • Microservices: It can act as a powerful back-end for microservices, efficiently managing individual functions.
  • Scheduled Tasks: For running background tasks at fixed intervals, Lambda can be an excellent choice.

A Comprehensive Guide to AWS Lambda Features

Before we delve into bullet points explaining the features, it’s essential to grasp the broad spectrum of capabilities that AWS Lambda offers. Here are some key features:

  • Automatic Scaling: Lambda adjusts its capacity automatically, ensuring smooth operation even during demand spikes.
  • Stateless Functions: Every function runs in an independent environment, ensuring process integrity.
  • Built-in Fault Tolerance: Offers built-in fault tolerance with failover and backup options.

How Lambda Function Works

To understand the functioning of AWS Lambda, let’s consider its workflow. The service is event-driven, meaning it reacts to certain triggers like changes to data in AWS services or an HTTP request via API Gateway. Here’s how it works:

  • Event Trigger: An AWS service or HTTP request triggers the Lambda function.
  • Load Function: Lambda loads and runs the function in a secure environment.
  • Execute: The function accesses other AWS services or resources and performs its task.

How to Create Lambda Function in AWS

Creating an AWS Lambda function involves a few steps. Sign in to the AWS Management Console and navigate to the Lambda service. Then:

  1. Select ‘Create Function’: Begin the process.
  2. Choose Runtime Environment: Choose your preferred language, like Node.js, Python, or Java.
  3. Upload Code: You can upload your function code here.
  4. Set Triggers: Select triggers like S3 bucket or an HTTP request.
  5. Deploy: Click on the deploy button to activate the function.

How to Write AWS Lambda Functions in Java

Thanks to its robust ecosystem and extensive libraries, Java is a widely used language for developing Lambda functions. If you’re familiar with Java 8 or later versions, you’re probably aware of the functional interface in Java 8 and expressions. Lambda expression in Java 8 leverages these principles for efficient and streamlined coding. When developing AWS Lambda functions in Java, define your function as a class that implements the AWS Lambda RequestHandler interface.

The RequestHandler interface is part of the AWS SDK for Java, essential to interface with AWS services. Download and include the AWS SDK in your project’s dependencies to make the most out of AWS Lambda features. This SDK provides all the necessary APIs for AWS, including AWS Lambda, thus simplifying the process of defining and deploying Lambda functions.

Your Java class should implement the handleRequest method, which AWS Lambda calls when the function is invoked. The method signature should match the types for input and output objects, facilitating seamless integration.

Once your function is ready, package it as a JAR file and upload it to AWS Lambda. You can also set triggers that invoke your Lambda function automatically, like an S3 bucket event or an HTTP request via API Gateway.

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How to Write AWS Lambda Python

Python stands out for its simplified syntax and ease of use, making it a popular choice for quick deployments on AWS Lambda. The AWS SDK for Python, known as Boto3, is an indispensable developer tool. It provides an object-oriented API, low-level access to AWS services, and various utilities to help you write Python scripts for AWS Lambda.

Upload the code to AWS Lambda, specify the function handler and runtime environment as Python, and the function is ready for invocation. Test the function through the AWS console or programmatically using Boto3.

AWS Lambda function in Python supports multiple versions, giving you flexibility in your choice of runtime. Python libraries or dependencies can be included in your deployment package, ensuring the function has all it needs to execute.

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Decoding the Role of AWS Serverless Lambda Architecture

The term AWS serverless architecture has gained immense traction in the technology industry, and AWS Lambda stands at the forefront of this paradigm shift. Serverless does not mean no servers are involved; rather, it signifies the abstraction of server management away from the developer’s responsibilities. AWS Lambda achieves this abstraction remarkably well, making it an integral part of the serverless architecture.

At its core, AWS Lambda allows you to run code without provisioning or managing servers. Simply put, you only focus on writing your function, and AWS takes care of the rest, including scalability, patching, and administration. This focus shift away from infrastructure management is an absolute game-changer. Developers can now focus solely on business logic and code development, accelerating the entire development cycle.

One compelling aspect of AWS Lambda is its event-driven nature. Functions (or Lambdas) are executed in response to specific events, such as changes in data, system state, or user actions. The utility of event-driven programming in a serverless context is immeasurable as it leads to efficient resource use. Lambda functions automatically scale depending on the number of incoming events, optimising resource allocation and cost.

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Real-world Applications: AWS Lambda Use Cases

AWS Lambda is incredibly versatile, offering a range of applications that go beyond mere function execution. Among the most common use cases for AWS Lambda are data processing, real-time file processing, and automated backups.

  • Data processing: With AWS Lambda, you can easily build data processing systems that absorb and transform large volumes of data and load it into another system. From stream processing to batch processing, AWS Lambda can handle it all.
  • Real-time file processing: Whenever new files are uploaded into services like Amazon S3, Lambda functions can automatically trigger to read the files, process them and store the output where needed. This capability is advantageous in real-time analytics and image or video processing scenarios.
  • Automated Backups: Regular backup is critical for any business. AWS Lambda can automate this by taking snapshots of your database and storing them in a secure location, such as Amazon S3. You can set these to occur at specified intervals, ensuring your data is always safeguarded.

Advantages of Adopting AWS Lambda

At its essence, AWS Lambda transforms how organisations think about computing and application development, aligning with the demands of agile, efficient, and cost-effective practices.

  • Reduced Operational Overhead: One of the most significant benefits is that it removes the need for server management. Developers don’t need to worry about the underlying infrastructure, software patches, or server failures. This lessens the operational burden, allowing teams to focus on creating value for the business.
  • Flexible Scaling: AWS Lambda scales automatically. Whether you’re executing a single Lambda function or a thousand parallel functions, AWS takes care of scaling the request handling capacity in an elastic manner. This agility allows for superior responsiveness to changes in workload without manual intervention.
  • Event-Driven Architecture: It perfectly aligns with event-driven architecture. Events like data modifications, system state shifts, or user actions can automatically trigger Lambda functions. This ensures real-time processing and timely actions, adding another layer of automation to system interactions.

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Knowing the Constraints: AWS Lambda Limitations

While it comes loaded with numerous advantages, it’s also essential to be aware of the limitations of AWS Lambda.

  • 15-minute Timeout: One of the major constraints is the 15-minute execution timeout for each function. This makes it unsuitable for long-running processes and tasks that require extensive computation time.
  • Cold Starts: The first time a Lambda function is invoked after being idle can result in a latency spike, commonly called a cold start. While this may not be a significant issue for many applications, it can be a bottleneck for real-time systems requiring instant responses.
  • Limited Customisation: AWS Lambda offers several built-in integrations, but its customisation capabilities are not limitless. Lambda may be somewhat constraining if your application requires specific libraries or unique setup configurations.

A Closer Look at AWS Lambda Pricing Structure

The Lambda function pricing generally starts at INR 16.54 per million requests, coupled with a cost for the compute time, which is measured in gigabyte-seconds (GB-seconds). It’s especially beneficial for professionals focused on cost-efficient solutions, allowing you to optimise spending based on actual usage. Remember, the more efficiently your functions run, the less you pay. 

AWS Lambda or AWS EC2: What Suits You?

When considering cloud computing services, Amazon offers a variety, but the choice between AWS Lambda and AWS EC2 is often a point of confusion. AWS Lambda excels in scenarios requiring the execution of back-end tasks without the need to manage servers. It automates server management tasks, such as patching, and allows you to focus on your code solely. 

On the other hand, AWS EC2 provides a more traditional, server-based environment, offering you greater control over the server but requiring manual management like patching, scaling, and backups. Lambda is more cost-effective for event-driven, short-lived applications because you only pay for the actual compute time. 

EC2, meanwhile, may be more suitable for long-running tasks and applications requiring complex, customisable environments. Understanding the nuances between Lambda and EC2 is vital for professionals looking to make the most out of Amazon’s cloud offerings.

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Mastering AWS Lambda: Best Practices Unveiled

When working with AWS Lambda functions, it’s not just about what you can do but how well you can do it. Following the best practices ensures that you get the most out of your Lambda functions in terms of performance, scalability, and maintainability. These best practices are not just guidelines but insights drawn from real-world applications that have scaled and succeeded.

  • Single-Purposed Functions: One of the initial and most important rules is to keep your Lambda functions focused on doing one thing and doing it well. Single-responsibility functions are easier to manage, debug, and scale. When each function has a specific job, it makes the system modular and more straightforward to update.
  • Reduced Package Size: The package size of your Lambda function directly impacts the cold start latency. Always aim to include only the libraries or dependencies that are essential for your function. Smaller package sizes mean quicker deployments and lower latency, enhancing your application’s overall performance.
  • Error Handling: Implementing proper error-handling mechanisms is crucial. Whether it’s a database that didn’t respond, a null object, or an unhandled exception, your function should be prepared to handle it gracefully. Using dead-letter queues (DLQs) or setting up retry policies can help manage errors effectively.


Understanding AWS Lambda is essential for anyone diving into serverless architecture. Its diverse features, cost-effectiveness, and scalability make it an indispensable tool for modern cloud-based applications.

What is AWS Lambda vs Lambda function?

AWS Lambda is a service, while a Lambda function is the specific code executed by AWS Lambda.

What is Lambda function in DevOps?

In DevOps, Lambda functions can automate tasks and integrate with various AWS services.

Is AWS Lambda an API?

AWS Lambda isn’t an API, but API Gateway can trigger it.

What language is used in AWS Lambda?

AWS Lambda supports multiple languages like Node.js, Python, and Java.

Why is AWS serverless function considered so?

AWS Lambda is considered serverless because it allows developers to run code without managing servers.

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