AWS Lambda Web Adapter

A tool to run web applications on AWS Lambda

AWS Lambda Web Adapter allows developers to build web apps (http api) with familiar frameworks (e.g. Express.js, Next.js, Flask, SpringBoot, ASP.NET and Laravel, anything speaks HTTP 1.1/1.0) and run it on AWS Lambda. The same docker image can run on AWS Lambda, Amazon EC2, AWS Fargate, and local computers.

📖 Read the full User Guide

Features

• Run web applications on AWS Lambda
• Supports Amazon API Gateway Rest API and Http API endpoints, Lambda Function URLs, and Application Load Balancer
• Supports Lambda managed runtimes, custom runtimes and docker OCI images
• Supports Lambda Managed Instances for multi-concurrent request handling
• Supports any web frameworks and languages, no new code dependency to include
• Automatic encode binary response
• Enables graceful shutdown
• Supports response payload compression
• Supports response streaming
• Supports multi-tenancy via tenant ID propagation
• Supports non-http event triggers

Quick Start

Docker Images

Add one line to your Dockerfile:

COPY --from=public.ecr.aws/awsguru/aws-lambda-adapter:1.0.0 /lambda-adapter /opt/extensions/lambda-adapter

Pre-compiled multi-arch images (x86_64 and arm64) are available at public.ecr.aws/awsguru/aws-lambda-adapter. Non-AWS base images may be used since the Runtime Interface Client ships with the Lambda Web Adapter.

👉 Docker Images guide

Zip Packages

1. Attach the Lambda Web Adapter layer to your function:
   • x86_64: arn:aws:lambda:${AWS::Region}:753240598075:layer:LambdaAdapterLayerX86:27
   • arm64: arn:aws:lambda:${AWS::Region}:753240598075:layer:LambdaAdapterLayerArm64:27
2. Set environment variable AWS_LAMBDA_EXEC_WRAPPER to /opt/bootstrap
3. Set function handler to your startup script, e.g. run.sh

👉 Zip Packages guide (includes AWS China region ARNs and Windows caveats)

Configurations

The readiness check port/path and traffic port can be configured using environment variables. These environment variables can be defined either within docker file or as Lambda function configuration.

Environment Variable	Description	Default
AWS_LWA_PORT	traffic port (falls back to PORT)	"8080"
AWS_LWA_READINESS_CHECK_PORT	readiness check port	AWS_LWA_PORT
AWS_LWA_READINESS_CHECK_PATH	readiness check path	"/"
AWS_LWA_READINESS_CHECK_PROTOCOL	readiness check protocol: "http" or "tcp"	"http"
AWS_LWA_READINESS_CHECK_HEALTHY_STATUS	HTTP status codes considered healthy (e.g., "200-399")	"100-499"
AWS_LWA_ASYNC_INIT	enable asynchronous initialization for long initialization functions	"false"
AWS_LWA_REMOVE_BASE_PATH	the base path to be removed from request path	None
AWS_LWA_ENABLE_COMPRESSION	enable gzip/br compression for response body (buffered mode only)	"false"
AWS_LWA_INVOKE_MODE	Lambda function invoke mode: "buffered" or "response_stream"	"buffered"
AWS_LWA_PASS_THROUGH_PATH	the path for receiving event payloads from non-http triggers	"/events"
AWS_LWA_AUTHORIZATION_SOURCE	a header name to be replaced to Authorization	None
AWS_LWA_ERROR_STATUS_CODES	HTTP status codes that will cause Lambda invocations to fail (e.g. "500,502-504")	None
AWS_LWA_LAMBDA_RUNTIME_API_PROXY	overwrites AWS_LAMBDA_RUNTIME_API to allow proxying request	None

Deprecation Notice: The following non-namespaced environment variables are deprecated and will be removed in version 2.0: HOST, READINESS_CHECK_PORT, READINESS_CHECK_PATH, READINESS_CHECK_PROTOCOL, REMOVE_BASE_PATH, ASYNC_INIT. Please migrate to the AWS_LWA_ prefixed versions. Note: PORT is not deprecated and remains a supported fallback for AWS_LWA_PORT.

Additionally, AWS_LWA_READINESS_CHECK_MIN_UNHEALTHY_STATUS has been removed in 1.0. Use AWS_LWA_READINESS_CHECK_HEALTHY_STATUS instead.

👉 Detailed configuration docs

Examples

• FastAPI
• FastAPI in Zip
• FastAPI with Background Tasks
• FastAPI with Response Streaming
• FastAPI with Response Streaming in Zip
• FastAPI with Response Streaming on Lambda Managed Instances
• FastAPI Response Streaming Backend with IAM Auth
• Flask
• Flask in Zip
• Serverless Django by @efi-mk
• Express.js
• Express.js in Zip
• Next.js
• Next.js in Zip
• Next.js Response Streaming
• SpringBoot
• SpringBoot in Zip
• SpringBoot Response Streaming
• Nginx
• PHP
• Rust Actix Web in Zip
• Rust Axum in Zip
• Golang Gin
• Golang Gin in Zip
• Deno Oak in Zip
• Laravel on Lambda
• ASP.NET MVC
• ASP.NET MVC in Zip
• ASP.NET Web API in Zip
• SQS Express.js
• Bedrock Agent FastAPI
• Bedrock Agent FastAPI in Zip
• FastHTML
• FastHTML in Zip
• FastHTML with Response Streaming
• FastHTML with Response Streaming in Zip
• Remix
• Remix in Zip
• Sveltekit SSR Zip
• Datadog
• Datadog in Zip

👉 Examples organized by language

Acknowledgement

This project was inspired by several community projects.

• re:Web
• Serverlessish

Migrating from 0.x to 1.0

Environment Variables

All environment variables now use the AWS_LWA_ prefix. The old non-prefixed names still work but are deprecated and will be removed in version 2.0.

Old (Deprecated)	New
READINESS_CHECK_PORT	AWS_LWA_READINESS_CHECK_PORT
READINESS_CHECK_PATH	AWS_LWA_READINESS_CHECK_PATH
READINESS_CHECK_PROTOCOL	AWS_LWA_READINESS_CHECK_PROTOCOL
REMOVE_BASE_PATH	AWS_LWA_REMOVE_BASE_PATH
ASYNC_INIT	AWS_LWA_ASYNC_INIT

Note: PORT is not deprecated and remains a supported fallback for AWS_LWA_PORT.

Readiness Check Health Status

AWS_LWA_READINESS_CHECK_MIN_UNHEALTHY_STATUS has been removed. Use AWS_LWA_READINESS_CHECK_HEALTHY_STATUS instead, which accepts comma-separated codes and ranges:

# Old
AWS_LWA_READINESS_CHECK_MIN_UNHEALTHY_STATUS=400

# New (equivalent)
AWS_LWA_READINESS_CHECK_HEALTHY_STATUS=100-399

Similar Projects

Several projects also provide similar capabilities as language specific packages/frameworks.

• Serverless Java Container
• Serverless Express
• Serverless Python - Zappa
• Serverless Rails - Lamby
• Serverless PHP - Bref

Security

See SECURITY for vulnerability reporting and CONTRIBUTING for more information.

License

This project is licensed under the Apache-2.0 License.