Redirect behavior for CloudFront with CDK and TypeScript

redirect-behavior.ts

import { Stack } from "aws-cdk-lib";
import { BehaviorOptions, Function, FunctionCode, FunctionEventType } from "aws-cdk-lib/aws-cloudfront";
import { HttpOrigin } from "aws-cdk-lib/aws-cloudfront-origins";
import { join } from "path";

export const getRedirectBehavior = (scope: Stack, id: string, location: string): BehaviorOptions => {
  const redirectFilePath = join(__dirname, 'redirect-function.js');
  const redirectFunctionCode = FunctionCode.fromFile({ filePath: redirectFilePath });
  const redirectFunction = new Function(scope, `${id}-default-redirect-function`, {
    code: redirectFunctionCode
  });

  // this origin will never be actually used, but we need to specify it to satisfy CloudFront
  const origin = new HttpOrigin(extractDomain(location));

  return {
    origin,
    functionAssociations: [
      {
        eventType: FunctionEventType.VIEWER_REQUEST,
        function: redirectFunction
      }
    ]
  };
}

const extractDomain = (url: string) => {
  // 1. Remove protocol (https:// or http://)
  url = url.replace(/(^\w+:\/\/)/i, "");

  // 2. Remove path (everything after the slash
  const slashIndex = url.indexOf("/");
  if (slashIndex !== -1) {
    url = url.substring(0, slashIndex);
  }

  return url;
}

redirect-function.js

function handler() {
  var REDIRECT_URL = 'https://example.com/some-path';
  return { statusCode: 301, headers: { location: { value: REDIRECT_URL } } }
}