dotfiles-redirector-stack.ts

import { Stack, StackProps, RemovalPolicy } from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as s3 from 'aws-cdk-lib/aws-s3';
import * as cloudfront from 'aws-cdk-lib/aws-cloudfront';
import * as origins from 'aws-cdk-lib/aws-cloudfront-origins';
import * as acm from 'aws-cdk-lib/aws-certificatemanager';

export interface DotfilesRedirectorStackProps extends StackProps {
  readonly certificateArn: string;
}

export class DotfilesRedirectorStack extends Stack {
  constructor(scope: Construct, id: string, props: DotfilesRedirectorStackProps) {
    super(scope, id, props);

    const { certificateArn } = props;

    const bucket = new s3.Bucket(this, 'dummy-origin-bucket', {
      removalPolicy: RemovalPolicy.DESTROY,
    });

    const cfFunction = new cloudfront.Function(this, 'redirector-function', {
      code: cloudfront.FunctionCode.fromFile({ filePath: 'src/cf-functions/redirect.js' }),
    });

    const distribution = new cloudfront.Distribution(this, 'redirector-distribution', {
      certificate: acm.Certificate.fromCertificateArn(this, 'redirector-certificate', certificateArn),
      domainNames: [ 'dot.masawada.me' ],
      defaultBehavior: {
        origin: new origins.S3Origin(bucket),
        functionAssociations: [{
          function: cfFunction,
          eventType: cloudfront.FunctionEventType.VIEWER_REQUEST,
        }],
      },
    });
  }
}

redirect.js

function handler(event) {
  var request = event.request;
  var headers = request.headers;
  var host = request.headers.host.value;
  var uri = request.uri;

  if (host !== 'dot.masawada.me') {
    return {
      statusCode: 400,
      statusDescription: 'Bad Request',
    };
  }

  var newUrl = `https://raw.githubusercontent.com/masawada/dotfiles/main${uri}`;

  return {
    statusCode: 302,
    statusDescription: 'Found',
    headers: { location: { value: newUrl } },
  };
}