AWS Lambda
Have you ever wondered how AWS Lambda actually works? Despite being called “serverless,” Lambda does run on servers—the key idea is that you don’t manage those servers. AWS (or other cloud providers like GCP or Azure) handles provisioning, scaling, patching, and capacity for you.That’s what serverless means: no server management, not “no servers.”
How does a Lambda function work?
There are many use cases for Lambda. Here’s a simple example:
Let’s say you have a spreadsheet containing user data with email addresses, and you want to send promotional emails to these users. You don’t want to build and host an entire application just to do this.
This is where the power of Lambda shines:
Upload File to S3 You start by creating an S3 bucket to store your spreadsheet.
Configure S3 → Lambda Trigger You set up an event so that whenever a new file is uploaded to this bucket, it automatically triggers a Lambda function.
Lambda Processing When the file is uploaded:
AWS triggers your Lambda function.
The function reads the spreadsheet.
It parses the user data.
It sends the promotional emails using whichever service you choose (SES, a third-party API, etc.).
Automatic Scaling If the file is large—or if multiple files come in at the same time—Lambda automatically scales to handle the load. You don’t need to manually increase server size or spin up new instances.
Cost Optimization Once the job is finished, Lambda scales back down to zero. You only pay for:
The number of invocations
The duration your code ran
The memory you allocated
No idle servers. No unnecessary charges.