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Ship a Lambda Web Function with CDK

Ship a Lambda Web Function with CDK

A first look at how you can deploy a lambda web function with CDK

Sean Boult

Developer. Hacker. Creator.
So,  AWS Lambda Web Functions  just came out, and I'm super excited about them.

What are they? Well, you can now ship Express, Hono, or React Router with no Lambda-specific adapters or wrappers.

Let me show you how I got this demo set up with CDK.

λ:  https://cxrj1w1j65n0k7ss.p7v.lambda-web.us-east-2.on.aws  (this may not live forever but the code should)
⚠️ DISCLAIMER: The code we are about to see is written with L1 CDK constructs. The L2 constructs are being tracked via  this PR .
First, let's look at the server code I have in Express. I've omitted the bulk of its logic for brevity.

Here, you can see that it's an  Express.js  server binding to a port.
ts
import express from "express";

const [hostname, rawPort] = (
  process.env.AWS_LAMBDA_HTTP_ENDPOINT ??
  `127.0.0.1:${process.env.PORT ?? "3000"}`
).split(":");
const port = Number(rawPort);

export const app = express();

export const server = app.listen(port, hostname, () => {
  console.log(`Spinning Lambda is listening on http://${hostname}:${port}`);
});

I can run the code locally with  pnpm dev .


Now, let's look at the CDK stack used to deploy this function.
ts
export class SpinningLambdaStack extends Stack {
  constructor(scope: Construct, id: string, props?: StackProps) {
    super(scope, id, props);
    
    // code bucket stuff omitted
    const webFunction = new CfnWebFunction(this, "WebFunction", {
      functionName: `${this.stackName}-web`,
      // many props omitted for brevity
    });

    const revision = new CfnWebFunctionRevision(this, "WebFunctionRevision", {
      functionName: webFunction.ref,
      // many props omitted for brevity
    });

    const endpoint = new CfnWebFunctionEndpoint(this, "WebFunctionEndpoint", {
      functionName: webFunction.ref,
      // many props omitted for brevity
    });

  }
}


Now for deployment. I'm using the  new AWS experience , so I have a  project  dedicated to this demo.

I grab some credentials for my account with  aws login . I need to do a one-time setup to bootstrap CDK with  npx cdk bootstrap .
Once that's done, I can run  pnpm deploy  to ship it.

Then it's live 🚀!


Share this on X/Twitter, and it should render as an embed:
plaintext
https://cxrj1w1j65n0k7ss.p7v.lambda-web.us-east-2.on.aws/embed


Full repo:  https://github.com/sboult/lwf-three-js 



As always, happy coding 😉!
Any opinions in this article are those of the individual author and may not reflect the opinions of AWS.
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