The Lambda Runtime Interface Emulator is a proxy for Lambda’s Runtime and Extensions APIs, which allows customers to
locally test their Lambda function packaged as a container image. It is a lightweight web-server that converts
HTTP requests to JSON events and maintains functional parity with the Lambda Runtime API in the cloud. It
allows you to locally test your functions using familiar tools such as cURL and the Docker CLI (when testing
functions packaged as container images). It also simplifies running your application on additional computes.
You can include the Lambda Runtime Interface Emulator in your container image to have it accept HTTP
requests instead of the JSON events required for deployment to Lambda. This component does not emulate
Lambda’s orchestrator, or security and authentication configurations. You can get started by downloading and installing it on your local machine. When the Lambda Runtime API emulator is executed, a /2015-03-31/functions/function/invocations endpoint will be stood up within the container that you post data to it in order to invoke your function for testing.
Instructions for installing AWS Lambda Runtime Interface Emulator for your platform
| Platform | Command to install |
|---|---|
| macOS/Linux x86_64 | mkdir -p ~/.aws-lambda-rie && curl -Lo ~/.aws-lambda-rie/aws-lambda-rie https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie && chmod +x ~/.aws-lambda-rie/aws-lambda-rie |
| macOS/Linux arm64 | mkdir -p ~/.aws-lambda-rie && curl -Lo ~/.aws-lambda-rie/aws-lambda-rie https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie-arm64 && chmod +x ~/.aws-lambda-rie/aws-lambda-rie |
| Windows x86_64 | Invoke-WebRequest -OutFile 'C:\Program Files\aws lambda\aws-lambda-rie' https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie |
| Windows arm64 | Invoke-WebRequest -OutFile 'C:\Program Files\aws lambda\aws-lambda-rie' https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie-arm64 |
There are a few ways you use the Runtime Interface Emulator (RIE) to locally test your function depending on the base image used.
The AWS base images for Lambda include the runtime interface emulator. You can also follow these steps if you built the RIE into your alternative base image.
-
Build your image locally using the docker build command.
docker build -t myfunction:latest . -
Run your container image locally using the docker run command.
docker run -p 9000:8080 myfunction:latestThis command runs the image as a container and starts up an endpoint locally at
localhost:9000/2015-03-31/functions/function/invocations. -
Post an event to the following endpoint using a curl command:
curl -XPOST "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{}'This command invokes the function running in the container image and returns a response.
You can build RIE into a base image. Download the RIE from GitHub to your local machine and update your Dockerfile to install RIE.
-
Create a script and save it in your project directory. Set execution permissions for the script file.
The script checks for the presence of the
AWS_LAMBDA_RUNTIME_APIenvironment variable, which indicates the presence of the runtime API. If the runtime API is present, the script runs the runtime interface client. Otherwise, the script runs the runtime interface emulator.The following example shows a typical script for a Node.js function.
#!/bin/sh if [ -z "${AWS_LAMBDA_RUNTIME_API}" ]; then exec /usr/local/bin/aws-lambda-rie /usr/bin/npx aws-lambda-ric else exec /usr/bin/npx aws-lambda-ric fi
-
Download the runtime interface emulator for your target architecture (
aws-lambda-riefor x86_64 oraws-lambda-rie-arm64for arm64) from GitHub into your project directory. -
Install the emulator package and change
ENTRYPOINTto run the new script by adding the following lines to your Dockerfile:To use the default x86_64 architecture
ADD aws-lambda-rie /usr/local/bin/aws-lambda-rie ENTRYPOINT [ "/entry_script.sh" ]
To use the arm64 architecture:
ADD aws-lambda-rie-arm64 /usr/local/bin/aws-lambda-rie ENTRYPOINT [ "/entry_script.sh" ]
-
Build your image locally using the docker build command.
docker build -t myfunction:latest . -
Run your image locally using the docker run command.
docker run -p 9000:8080 myfunction:latest
You install the runtime interface emulator to your local machine. When you run the container image, you set the entry point to be the emulator.
-
From your project directory, run the following command to download the RIE (x86-64 architecture) from GitHub and install it on your local machine.
mkdir -p ~/.aws-lambda-rie && curl -Lo ~/.aws-lambda-rie/aws-lambda-rie \ https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie \ && chmod +x ~/.aws-lambda-rie/aws-lambda-rie
To download the RIE for arm64 architecture, use the previous command with a different GitHub download url.
https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie-arm64 \ -
Run your Lambda image function using the docker run command.
docker run -d -v ~/.aws-lambda-rie:/aws-lambda -p 9000:8080 myfunction:latest \ --entrypoint /aws-lambda/aws-lambda-rie <image entrypoint> <(optional) image command>
This runs the image as a container and starts up an endpoint locally at
localhost:9000/2015-03-31/functions/function/invocations. -
Post an event to the following endpoint using a curl command:
curl -XPOST "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{}'
This command invokes the function running in the container image and returns a response.
aws-lambda-rie can be configured through Environment Variables within the local running Image.
You can configure your credentials by setting:
AWS_ACCESS_KEY_IDAWS_SECRET_ACCESS_KEYAWS_SESSION_TOKENAWS_REGION
You can configure timeout by setting AWS_LAMBDA_FUNCTION_TIMEOUT to the number of seconds you want your function to timeout in.
The rest of these Environment Variables can be set to match AWS Lambda's environment but are not required.
AWS_LAMBDA_FUNCTION_VERSIONAWS_LAMBDA_FUNCTION_NAMEAWS_LAMBDA_FUNCTION_MEMORY_SIZE
You can use the emulator to test if your function code is compatible with the Lambda environment, executes successfully and provides the expected output. For example, you can mock test events from different event sources. You can also use it to test extensions and agents built into the container image against the Lambda Extensions API. This component does not emulate the orchestration behavior of AWS Lambda. For example, Lambda has a network and security configurations that will not be emulated by this component.
- You can use the emulator to test if your function code is compatible with the Lambda environment, runs successfully and provides the expected output.
- You can also use it to test extensions and agents built into the container image against the Lambda Extensions API.
- This component does not emulate Lambda’s orchestration, or security and authentication configurations.
- The component does not support X-ray and other Lambda integrations locally.
- The component supports only Linux, for x86-64 and arm64 architectures.
See CONTRIBUTING for more information.
This project is licensed under the Apache-2.0 License.