Lambda is a serverless service, but remember that serverless does not mean that it does’nt run on a server. It simply means that you don’t manage the servers software or hardware, it’s a PaaS, platform as a service. It allows you to run your code without provisioning servers.

The introduction to Lambda

AWS Lambda is a serverless computing service that allows you to run code in response to various events, such as changes to data in an Amazon S3 bucket, updates to a DynamoDB table, HTTP requests via Amazon API Gateway, and more. It automatically scales your application, ensuring it runs efficiently without the need to manage servers or infrastructure.


At the heart of AWS Lambda is the concept of a function. A function is a piece of code that can be executed in response to an event. Functions are typically written in languages like Python, Node.js, Java, and more. You can package your code, dependencies, and configuration into a deployment package and upload it to AWS Lambda.

Event source

Event sources are the triggers that invoke Lambda functions. These can be services like S3, SNS, DynamoDB, CloudWatch Events, or custom sources via API Gateway. Each event source generates events that are used to invoke one or more Lambda functions.


Lambda functions can be invoked in several ways:

  • Synchronous invocation: Invoked directly via the AWS Lambda API or through AWS SDKs.
  • Asynchronous invocation: Triggered by events from event sources like S3 or SNS.
  • Stream-based invocation: Process records from AWS services like Kinesis or DynamoDB Streams.

Benefits of using AWS Lambda


AWS Lambda automatically scales your application by running code in response to each trigger, handling high volumes of requests without manual intervention.


You pay only for the compute time consumed while your code is running, making it cost-effective for variable workloads.

No Server Management

You are freed from server provisioning, patching, and maintenance tasks, allowing you to focus on writing code.

Built-in High Availability

AWS Lambda provides built-in high availability and fault tolerance by running code across multiple Availability Zones.

Ecosystem Integration

Integrate Lambda with various AWS services and third-party tools, making it an integral part of your application architecture.

Usage examples

Let’s take three real world use cases where you could utilize AWS Lambda.

Image Resizing

You can create a Lambda function that resizes images uploaded to an S3 bucket. When an image is added, an S3 event triggers the Lambda function, which resizes the image and stores it back in the bucket. This is a common use case for handling media files in web applications.

Real-time Data Processing

Lambda functions are perfect for real-time data processing. For instance, you can use Lambda to analyze log data from an application, extract meaningful insights, and send alerts or store processed data in a database.

Scheduled Tasks

Lambda can also be used for scheduled tasks, such as taking daily backups, cleaning up old data, or sending out regular reports. You can schedule Lambda functions to run at specific times using CloudWatch Events.

Integration with other AWS services

AWS Lambda seamlessly integrates with various AWS services, enhancing its functionality. A few popular services:

  • Amazon API Gateway: Create RESTful APIs with Lambda functions as the backend.
  • Amazon S3: Trigger Lambda functions when objects are created or modified in S3 buckets.
  • Amazon DynamoDB: Automatically invoke Lambda functions in response to database changes.
  • Amazon SNS: Use Lambda to process notifications and take action.


AWS provides tools like CloudWatch Logs and CloudWatch Metrics for monitoring Lambda functions. You can set up alarms, create custom metrics, and gain insights into function performance. Additionally, AWS X-Ray can help trace and debug distributed applications.

Security and permissions

AWS Identity and Access Management (IAM) allows you to define fine-grained permissions for Lambda functions. You can control what AWS resources a Lambda function can access, ensuring security best practices are followed.

AWS Lambda best practices and pricing

Lambda pricing is based on the number of requests and the compute time consumed. There is a generous free tier available, making it cost-effective for many use cases. Always check the AWS Lambda pricing page for up-to-date information.

To make the most of AWS Lambda, consider these best practices:

  • Keep Functions Stateless: Avoid storing state in your function code; use external storage like databases or caches.
  • Optimize Package Size: Minimize deployment package size to reduce cold start times.
  • Use VPCs Wisely: Carefully configure Virtual Private Cloud (VPC) settings for Lambda functions.
  • Handle Errors Gracefully: Implement proper error handling and retry mechanisms.
  • Monitor and Tune Performance: Regularly monitor and fine-tune your Lambda functions for optimal performance.

By awstalk

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