Lambda

--- name: lambda description: AWS Lambda serverless functions for event-driven compute. Use when creating functions, configuring triggers, debugging invocations, optimizing cold starts, setting up event source mappings, or managing layers. lastupdated: "2026-01-07" docsource: https://docs.aws.amazon.com/lambda/latest/dg/ --- # AWS Lambda AWS Lambda runs code without provisioning servers. You pay only for compute time consumed. Lambda automatically scales from a few requests per day to thousands per second. ## Table of Contents - [Core Concepts](#core-concepts) - [Common Patterns](#common-patterns) - [CLI Reference](#cli-reference) - [Best Practices](#best-practices) - [Troubleshooting](#troubleshooting) - [References](#references) ## Core Concepts ### Function Your code packaged with configuration. Includes runtime, handler, memory, timeout, and IAM role. ### Invocation Types | Type | Description | Use Case | |------|-------------|----------| | Synchronous | Caller waits for response | API Gateway, direct invoke | | Asynchronous | Fire and forget | S3, SNS, EventBridge | | Poll-based | Lambda polls source | SQS, Kinesis, DynamoDB Streams | ### Execution Environment Lambda creates execution environments to run your function. Components: - Cold start: New environment initialization - Warm start: Reusing existing environment - Handler: Entry point function - Context: Runtime information ### Layers Reusable packages of libraries, dependencies, or custom runtimes (up to 5 per function). ## Common Patterns ### Create a Python Function AWS CLI: ``bash # Create deployment package zip function.zip lambda_function.py # Create function aws lambda create-function \ --function-name MyFunction \ --runtime python3.12 \ --role arn:aws:iam::123456789012:role/lambda-role \ --handler lambda_function.handler \ --zip-file fileb://function.zip \ --timeout 30 \ --memory-size 256 # Update function code aws lambda update-function-code \ --function-name MyFunction \ --zip-file fileb://function.zip ` **boto3:** `python import boto3 import zipfile import io lambda_client = boto3.client('lambda') # Create zip in memory zip_buffer = io.BytesIO() with zipfile.ZipFile(zip_buffer, 'w') as zf: zf.writestr('lambda_function.py', ''' def handler(event, context): return {"statusCode": 200, "body": "Hello"} ''') zip_buffer.seek(0) # Create function lambda_client.create_function( FunctionName='MyFunction', Runtime='python3.12', Role='arn:aws:iam::123456789012:role/lambda-role', Handler='lambda_function.handler', Code={'ZipFile': zip_buffer.read()}, Timeout=30, MemorySize=256 ) ` ### Add S3 Trigger `bash # Add permission for S3 to invoke Lambda aws lambda add-permission \ --function-name MyFunction \ --statement-id s3-trigger \ --action lambda:InvokeFunction \ --principal s3.amazonaws.com \ --source-arn arn:aws:s3:::my-bucket \ --source-account 123456789012 # Configure S3 notification (see S3 skills) ` ### Add SQS Event Source `bash aws lambda create-event-source-mapping \ --function-name MyFunction \ --event-source-arn arn:aws:sqs:us-east-1:123456789012:my-queue \ --batch-size 10 \ --maximum-batching-window-in-seconds 5 ` ### Environment Variables `bash aws lambda update-function-configuration \ --function-name MyFunction \ --environment "Variables={DB_HOST=mydb.cluster-xyz.us-east-1.rds.amazonaws.com,LOG_LEVEL=INFO}" ` ### Create and Attach Layer `bash # Create layer zip -r layer.zip python/ aws lambda publish-layer-version \ --layer-name my-dependencies \ --compatible-runtimes python3.12 \ --zip-file fileb://layer.zip # Attach to function aws lambda update-function-configuration \ --function-name MyFunction \ --layers arn:aws:lambda:us-east-1:123456789012:layer:my-dependencies:1 ` ### Invoke Function `bash # Synchronous invoke aws lambda invoke \ --function-name MyFunction \ --payload '{"key": "value"}' \ response.json # Asynchronous invoke aws lambda invoke \ --function-name MyFunction \ --invocation-type Event \ --payload '{"key": "value"}' \ response.json ` ## CLI Reference ### Function Management | Command | Description | |---------|-------------| | aws lambda create-function | Create new function | | aws lambda update-function-code | Update function code | | aws lambda update-function-configuration | Update settings | | aws lambda delete-function | Delete function | | aws lambda list-functions | List all functions | | aws lambda get-function | Get function details | ### Invocation | Command | Description | |---------|-------------| | aws lambda invoke | Invoke function | | aws lambda invoke-async | Async invoke (deprecated) | ### Event Sources | Command | Description | |---------|-------------| | aws lambda create-event-source-mapping | Add event source | | aws lambda list-event-source-mappings | List mappings | | a