How to Deploy Deno to AWS Lambda

AWS Lambda is a serverless computing service provided by Amazon Web Services. It allows you to run code without provisioning or managing servers.

Here's a step by step guide to deploying a Deno app to AWS Lambda using Docker.

The pre-requisites for this are:

• docker CLI
• an AWS account
• aws CLI

Step 1: Create a Deno App Jump to heading#

Create a new Deno app using the following code:

Deno.serve((req) => new Response("Hello World!"));

Save this code in a file named main.ts.

Step 2: Create a Dockerfile Jump to heading#

Create a new file named Dockerfile with the following content:

# Set up the base image
FROM public.ecr.aws/awsguru/aws-lambda-adapter:0.8.4 AS aws-lambda-adapter
FROM denoland/deno:bin-1.45.2 AS deno_bin
FROM debian:bookworm-20230703-slim AS deno_runtime
COPY --from=aws-lambda-adapter /lambda-adapter /opt/extensions/lambda-adapter
COPY --from=deno_bin /deno /usr/local/bin/deno
ENV PORT=8000
EXPOSE 8000
RUN mkdir /var/deno_dir
ENV DENO_DIR=/var/deno_dir

# Copy the function code
WORKDIR "/var/task"
COPY . /var/task

# Warmup caches
RUN timeout 10s deno run -A main.ts || [ $? -eq 124 ] || exit 1

CMD ["deno", "run", "-A", "main.ts"]

This Dockerfile uses the aws-lambda-adapter project to adapt regular HTTP servers, like Deno's Deno.serve, to the AWS Lambda runtime API.

We also use the denoland/deno:bin-1.45.2 image to get the Deno binary and debian:bookworm-20230703-slim as the base image. The debian:bookworm-20230703-slim image is used to keep the image size small.

The PORT environment variable is set to 8000 to tell the AWS Lambda adapter that we are listening on port 8000.

We set the DENO_DIR environment variable to /var/deno_dir to store cached Deno source code and transpiled modules in the /var/deno_dir directory.

The warmup caches step is used to warm up the Deno cache before the function is invoked. This is done to reduce the cold start time of the function. These caches contain the compiled code and dependencies of your function code. This step starts your server for 10 seconds and then exits.

When using a package.json, remember to run deno install to install node_modules from your package.json file before warming up the caches or running the function.

Step 3: Build the Docker Image Jump to heading#

Build the Docker image using the following command:

docker build -t hello-world .

Step 4: Create an ECR Docker repository and push the image Jump to heading#

With the AWS CLI, create an ECR repository and push the Docker image to it:

aws ecr create-repository --repository-name hello-world --region us-east-1 | grep repositoryUri

This should output a repository URI that looks like <account_id>.dkr.ecr.us-east-1.amazonaws.com/hello-world.

Authenticate Docker with ECR, using the repository URI from the previous step:

aws ecr get-login-password --region us-east-1 | docker login --username AWS --password-stdin <account_id>.dkr.ecr.us-east-1.amazonaws.com

Tag the Docker image with the repository URI, again using the repository URI from the previous steps:

docker tag hello-world:latest <account_id>.dkr.ecr.us-east-1.amazonaws.com/hello-world:latest

Finally, push the Docker image to the ECR repository, using the repository URI from the previous steps:

docker push <account_id>.dkr.ecr.us-east-1.amazonaws.com/hello-world:latest

Step 5: Create an AWS Lambda function Jump to heading#

Now you can create a new AWS Lambda function from the AWS Management Console.

1. Go to the AWS Management Console and navigate to the Lambda service.
2. Click on the "Create function" button.
3. Choose "Container image".
4. Enter a name for the function, like "hello-world".
5. Click on the "Browse images" button and select the image you pushed to ECR.
6. Click on the "Create function" button.
7. Wait for the function to be created.
8. In the "Configuration" tab, go to the "Function URL" section and click on "Create function URL".
9. Choose "NONE" for the auth type (this will make the lambda function publicly accessible).
10. Click on the "Save" button.

Step 6: Test the Lambda function Jump to heading#

You can now visit your Lambda function's URL to see the response from your Deno app.

🦕 You have successfully deployed a Deno app to AWS Lambda using Docker. You can now use this setup to deploy more complex Deno apps to AWS Lambda.