What is an AWS Lambda Function?

In the world of cloud development, AWS Lambda has become a
key tool for building modern, scalable, and serverless applications. But
what exactly is a Lambda function and why is it revolutionizing the way we
develop software?

Introduction to AWS Lambda

AWS Lambda is a computing service provided by Amazon Web Services (AWS)
that allows code to run without the need to provision or manage servers. This
model is known as “serverless computing.”

Instead of maintaining a server running 24/7, with Lambda you simply
upload your code, define the events that trigger it, and AWS takes care of the rest:
from execution to scalability and infrastructure maintenance.

What is a Lambda Function?

A Lambda function is a piece of code that you write and upload to AWS Lambda.
This function executes in response to a specific event, such as an HTTP request,
a file uploaded to Amazon S3, a database update, or even a
CRON job defined with Amazon EventBridge.

Main features:

• Events as triggers: Lambda is triggered by events from other AWS services (S3, DynamoDB, API Gateway, among others).
• Executes on demand: It only runs when an event occurs, which helps reduce costs.
• Automatic scaling: AWS automatically scales the function to handle multiple simultaneous executions.
• Pay-per-use: You only pay for execution time and number of invocations.

How does it work?

1. Write your function: It can be written in languages like Python, Node.js, Java, among others.
2. Upload it to AWS Lambda: Directly from the console, CLI, or as part of an application with infrastructure as code.
3. Define a trigger event: For example, a request via Amazon API Gateway.
4. Lambda executes your code: AWS automatically manages the resources to execute your code each time the event is triggered.
   

The following diagram shows a basic example of operation:

It can be seen that one or multiple events can invoke a Lambda function for a common purpose or multiple destinations.

Supported Languages

Below are the languages supported by AWS Lambda functions,
as well as their respective versions:

Language	Version	Operating System
NodeJS	20, 22	Amazon Linux 2023
NodeJS	18	Amazon Linux 2
Python	3.12	Amazon Linux 2023
Python	3.11, 3.19, 3.9	Amazon Linux 2
Java	21	Amazon Linux 2023
Java	17, 11, 8	Amazon Linux 2
.NET	9, 8	Amazon Linux 2023
Ruby	3.4, 3.3	Amazon Linux 2023
Ruby	3.2	Amazon Linux 2
OS-only		Amazon Linux 2 / 2023

Common Use Cases

• Image or file processing: When a file is uploaded to S3.
• Serverless APIs: Combining Lambda with API Gateway.
• Task automation: Such as sending notifications, backups, or data cleaning.
• Real-time processing: Such as data streams with Kinesis or DynamoDB Streams.

Advantages

• No need to manage servers.
• Automatic scalability.
• High availability.
• Cost reduction.
• Easy integration with other AWS services.

Additional Information

• Maximum duration: 15 minutes per execution.
• Memory allocation: Between 128 MB and 10,240 MB.
• Scalability: CPU and network scale proportionally with assigned memory.

• Pricing model: Only pay for actual execution time and number of invocations.
  AWS also provides a monthly free tier consisting of:

  • 1 million invocations
  • 400,000 GB-seconds of compute time

• Package size:

  • ZIP: up to 50 MB
  • Docker: up to 10 GB
• Security and roles: Each Lambda function uses an IAM role. It is essential to configure only the minimum necessary permissions.

• Monitoring and debugging:

  • Amazon Cloudwatch Logs: Logs events and errors.
  • X-Ray: Tracing and performance analysis.
  • AWS CloudTrail: Activity auditing.
• Versioning: It is possible to version functions, facilitating controlled deployments and separation of development, test, and production environments.

Conclusion

AWS Lambda represents a paradigm shift in how we think about and develop
our applications. By focusing solely on code and not infrastructure,
teams can move faster, pay less, and build more resilient
and scalable solutions. Lambda can be an excellent first step
into the world of serverless computing.

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