AWS Lambda is a serverless compute service that lets you run code without provisioning or managing servers.

In this guide, we will deploy a Bun HTTP server to AWS Lambda using a Dockerfile.

NOTE

Before continuing, make sure you have:

• A Bun application ready for deployment
• An AWS account
• AWS CLI installed and configured
• Docker installed and added to your PATH

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Create a new Dockerfile

Make sure you're in the directory containing your project, then create a new Dockerfile in the root of your project. This file contains the instructions to initialize the container, copy your local project files into it, install dependencies, and start the application.

# Use the official AWS Lambda adapter image to handle the Lambda runtime
FROM public.ecr.aws/awsguru/aws-lambda-adapter:0.9.0 AS aws-lambda-adapter

# Use the official Bun image to run the application
FROM oven/bun:debian AS bun_latest

# Copy the Lambda adapter into the container
COPY --from=aws-lambda-adapter /lambda-adapter /opt/extensions/lambda-adapter

# Set the port to 8080. This is required for the AWS Lambda adapter.
ENV PORT=8080

# Set the work directory to `/var/task`. This is the default work directory for Lambda.
WORKDIR "/var/task"

# Copy the package.json and bun.lock into the container
COPY package.json bun.lock ./

# Install the dependencies
RUN bun install --production --frozen-lockfile

# Copy the rest of the application into the container
COPY . /var/task

# Run the application.
CMD ["bun", "index.ts"]

NOTE

Make sure that the start command corresponds to your application's entry point. This can also be `CMD ["bun", "run", "start"]` if you have a start script in your `package.json`.

This image installs dependencies and runs your app with Bun inside a container. If your app doesn't have dependencies, you can omit the RUN bun install --production --frozen-lockfile line.

Create a new .dockerignore file in the root of your project. This file contains the files and directories that should be excluded from the container image, such as node_modules. This makes your builds faster and smaller:

node_modules
Dockerfile*
.dockerignore
.git
.gitignore
README.md
LICENSE
.vscode
.env
# Any other files or directories you want to exclude

Build the Docker image

Make sure you're in the directory containing your Dockerfile, then build the Docker image. In this case, we'll call the image bun-lambda-demo and tag it as latest.

# cd /path/to/your/app
docker build --provenance=false --platform linux/amd64 -t bun-lambda-demo:latest .

Create an ECR repository

To push the image to AWS Lambda, we first need to create an ECR repository to push the image to.

By running the following command, we:

• Create an ECR repository named bun-lambda-demo in the us-east-1 region
• Get the repository URI, and export the repository URI as an environment variable. This is optional, but make the next steps easier.

export ECR_URI=$(aws ecr create-repository --repository-name bun-lambda-demo --region us-east-1 --query 'repository.repositoryUri' --output text)
echo $ECR_URI

[id].dkr.ecr.us-east-1.amazonaws.com/bun-lambda-demo

NOTE

If you're using IAM Identity Center (SSO) or have configured AWS CLI with profiles, you'll need to add the `--profile` flag to your AWS CLI commands.

For example, if your profile is named my-sso-app, use --profile my-sso-app. Check your AWS CLI configuration with aws configure list-profiles to see available profiles.

export ECR_URI=$(aws ecr create-repository --repository-name bun-lambda-demo --region us-east-1 --profile my-sso-app --query 'repository.repositoryUri' --output text)
echo $ECR_URI

Authenticate with the ECR repository

Log in to the ECR repository:

aws ecr get-login-password --region us-east-1 | docker login --username AWS --password-stdin $ECR_URI

Login Succeeded

NOTE

If using a profile, use the `--profile` flag:

aws ecr get-login-password --region us-east-1 --profile my-sso-app | docker login --username AWS --password-stdin $ECR_URI

Tag and push the docker image to the ECR repository

Make sure you're in the directory containing your Dockerfile, then tag the docker image with the ECR repository URI.

docker tag bun-lambda-demo:latest ${ECR_URI}:latest

Then, push the image to the ECR repository.

docker push ${ECR_URI}:latest

Create an AWS Lambda function

Go to AWS Console > Lambda > Create Function > Select Container image

Give the function a name, like my-bun-function.

Select the container image

Then, go to the Container image URI section, click on Browse images. Select the image we just pushed to the ECR repository.

Then, select the latest image, and click on Select image.

Configure the function

To get a public URL for the function, we need to go to Additional configurations > Networking > Function URL.

Set this to Enable, with Auth Type NONE.

Create the function

Click on Create function at the bottom of the page, this will create the function.

Get the function URL

Once the function has been created you'll be redirected to the function's page, where you can see the function URL in the "Function URL" section.

Test the function

🥳 Your app is now live! To test the function, you can either go to the Test tab, or call the function URL directly.

curl -X GET https://[your-function-id].lambda-url.us-east-1.on.aws/

Hello from Bun on Lambda!