What is aws lambda

What is Serverless Computing?

AWS Lambda is the foundational service of serverless computing—a paradigm where cloud providers manage infrastructure, scaling, and operations automatically. Instead of provisioning EC2 instances, managing autoscaling groups, or maintaining containerized environments, developers write functions and Lambda handles everything else. This approach eliminates operational overhead while enabling rapid deployment and automatic resource management.

How Lambda Works

You upload function code to Lambda along with its dependencies. When triggered by an event (API request, file upload, database change, scheduled time, or message queue), Lambda automatically allocates computing resources, executes the function, and returns results. The execution environment is ephemeral—containers spin up on-demand and tear down after execution. This event-driven model makes Lambda ideal for processing, transformations, and integrations that don't require continuous availability.

Supported Languages and Runtimes

Lambda provides managed runtimes for Python 3.x, Node.js, Java, C#/.NET, Go, Ruby, and PHP. Custom runtimes enable you to use virtually any programming language. Each runtime includes commonly needed libraries and integrates with Lambda's execution environment, providing context about invocation details, logging, and resource limits.

Event Sources and Triggers

Lambda functions integrate seamlessly with AWS ecosystem triggers:

• API Gateway: HTTP/REST endpoints that invoke Lambda synchronously
• S3: Object creation, deletion, or modification events
• DynamoDB Streams: Database record changes
• SQS/SNS: Message queues and pub/sub notifications
• CloudWatch Events: Scheduled invocations (cron-like behavior)
• Cognito: User authentication events
• EventBridge: Custom application events and third-party integrations

Pricing and Cost Optimization

Lambda charges based on two dimensions: number of requests and compute duration in 1-millisecond increments. The free tier includes 1 million monthly requests and 400,000 GB-seconds of compute (equivalent to running a 128MB function for ~92 hours). This pricing model favors intermittent workloads—costs are zero when functions aren't running. For continuous workloads, traditional compute (EC2, Fargate, containers) may be more economical.

Limitations and Constraints

Lambda has specific constraints: maximum execution time of 15 minutes, temporary storage (/tmp) limited to 10GB, and payload size limits (6MB synchronous, 256KB asynchronous). For long-running or stateful workloads, these limitations may necessitate alternative services like Fargate or EC2.