Run AWS Lambda Locally with Docker

This guide walks you through running an AWS Lambda function written in Node.js using Docker, simulating AWS’s environment.

Step 1: Create a Dockerfile

FROM amazon/aws-lambda-nodejs:14

COPY . ${LAMBDA_TASK_ROOT}
RUN npm install

CMD ["index.handler"]

Replace index.handler with your actual handler filename and function.

Step 2: Build the Docker Image

docker build -t my-lambda-function .

Step 3: Run the Lambda Function

docker run -p 9000:8080 my-lambda-function

You can test the Lambda with a curl request:

curl -XPOST "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{"key": "value"}'

Step 4: Simulate Memory and Storage Limits

docker run -p 9000:8080 --memory 512m --tmpfs /tmp:rw,size=512m my-lambda-function

Option: Use Docker Compose

version: "3.8"
services:
  lambda:
    image: my-lambda-function
    ports:
      - "9000:8080"
    deploy:
      resources:
        limits:
          memory: 512m
    tmpfs:
      - /tmp:size=512m

Uploading Function Code

Method 1: Copy During Build (recommended for production)

Ensure your Dockerfile contains:

COPY . ${LAMBDA_TASK_ROOT}

Then build the image:

docker build -t my-lambda-function .

Method 2: Mount as Volume (recommended for development)

docker run -p 9000:8080 -v $(pwd):${LAMBDA_TASK_ROOT} my-lambda-function

This mounts your local code so changes are reflected without rebuilding.