CDK: switch to CloudFront EdgeFunction

[arjunnaha]

Is your feature request related to a problem? Please describe.
At the moment, CDK stacks have to be deployed to us-east-1 because of the Lambda@Edge function.

Describe the solution you'd like
The CloudFront module provides a (experimental) EdgeFunction module that behaves exactly like a normal Function, however if the stack is deployed to a region that isn't us-east-1, it will isolate the function into a new stack and create the function in the correct region.

Current blockers
I've tried to switch to EdgeFunction locally, and there are a few issues:

• version aliases clash (issue) fixed
• role circular dependency (issue)

Re the circular dependency, the only solution seems to be using another stack and importing the role in. We could have 'support' constructs that go into a separate shared stack, which would also solve #947.

[kirkness]

Hey Arjun, this sounds great. I'm hesitant to jump in a use an experimental module, although either way, I'll have a play with this myself.

[bobrossthepainter]

Hi,
first of all thanks for this super nice sls-component and the cdk adapter! Especially with being able to configure regions for S3 and SQS, it boosts up the performance of our webapp immensely. Back to the topic:

I just tried the switch to EdgeFunction by myself and it works in my scenario (just using the regeneration and default lambda).
I'm deploying the Stack in eu-central-1 and with switching all lambdas to EdgeFunctions (except the regeneration lambda), a us-1-region parent stack is automatically generated, containing the edge lambdas.
Furthermore, to overcome the circular role issue, I simply removed the custom role assigned to the edge lambdas, because the addition of the "edgelambda.amazonaws.com" Principal seems to be implicit for EdgeFunctions.

Cheers
Rob

[w0otness]

The role it assigns is the default one given... I just commented out the manual role assignment and it works.

diff --git a/node_modules/@sls-next/cdk-construct/dist/index.js b/node_modules/@sls-next/cdk-construct/dist/index.js

•    this.defaultNextLambda = new lambda.Function(this, "NextLambda", {
  

•    this.defaultNextLambda = new aws_cloudfront_1.experimental.EdgeFunction(this, "NextLambda", {
  

•        role: this.edgeLambdaRole,
  

•        // role: this.edgeLambdaRole,
  

[ChristopheBougere]

Thanks for the workaround @w0otness 👌

For the maintainers, would you accept a PR that would propose this change as an option in the construct props?

Meanwhile, here is a snippet of the patch if anyone is interested:

import * as fs from 'fs';
import * as path from 'path';
import * as cdk from 'aws-cdk-lib';

async function patchConstructCode() {
  const filePath = path.join(__dirname, 'node_modules/@sls-next/cdk-construct/dist/index.js');
  const fileContent = await (await fs.promises.readFile(filePath)).toString();
  await fs.promises.writeFile(
    filePath,
    fileContent.replace('lambda.Function(this, "NextLambda"', 'aws_cloudfront_1.experimental.EdgeFunction(this, "NextLambda"')
      .replace('role: this.edgeLambdaRole', '// role: this.edgeLambdaRole'),
  );
}

patchConstructCode()
  .then(() => import('@sls-next/lambda-at-edge'))
  .then(({ Builder }) => {
    const builder = new Builder('.', './build', { args: ['build'] });
    builder.build();
  })
  .then(() => {
    const app = new cdk.App();
    new MyStack(app, 'MyStack');
  })
  .catch((e) => {
    console.log(e);
    process.exit(1);
  });

[devlsh]

Any updates on this?