Lambda request origin and response origin functions for serving S3 content with a private bucket using Cloudfront as a CDN

index-doc-filter.js

// Request origin Lambda@Edge function
// As shown in https://www.youtube.com/watch?v=pFean2aj_8I AWS Online Tech Talk
// Deploying JAMStack Applications Using S3, CloudFront and Lambda@Edge 
exports.handler = async (event) => {
  const request = event.Records[0].cf.request;
  const uri = request.uri;

  if(uri.endsWith('/')) {
    request.uri += 'index.html';
  } else if (!uri.includes('.')) {
    request.uri += '/index.html';
  }

  return request;
}

redirect-manager.js

// Response origin Lambda@Edge function
exports.handler = async (event) => {
  var response = event.Records[0].cf.response;
  const headers = response.headers;
  const host = event.Records[0].cf.config['distributionDomainName'];

  if (headers['x-amz-website-redirect-location']) {
    var redirectURI = headers['x-amz-website-redirect-location'][0].value;
    if (redirectURI.startsWith('/')) {
      redirectURI = 'https://' + host + redirectURI;
    }

    response = {
      status: '302',
      statusDescription: 'Found',
      headers: {
        'location': [{
          key: 'Location',
          value: redirectURI,
        }],
        'cache-control': [{
          key: 'Cache-Control',
          value: 'public, max-age=300, s-maxage=3600'
        }]
      }
    }
  }


  return response;
}