Cloudfront function redirect

cloudfront_function_redirect.yml

AWSTemplateFormatVersion: 2010-09-09
Description: Cloudfront redirect lambda demo

Parameters:
  FromDomain:
    Type: String
    Default: darin.dev-code.org
    Description: The domain you wish to redirect traffic from
  ToDomain:
    Type: String
    Default: code.org
    Description: The domain you wish to redirect traffic to
  HostedZoneId:
    Type: String
    Description: The HostedZoneId for the To/From Domains
  RedirectType:
    Type: String
    Default: 302
    AllowedValues:
      - 301
      - 302
    Description: The redirect type, permanent or temporary


Resources:

  PrimaryRecord:
    Type: "AWS::Route53::RecordSet"
    Properties:
      HostedZoneId: !Ref HostedZoneId
      Name: !Ref FromDomain
      Type: A
      AliasTarget:
        HostedZoneId: Z2FDTNDATAQYW2
        DNSName: !GetAtt CFDistribution.DomainName

  CFDistribution:
    Type: AWS::CloudFront::Distribution
    Properties:
      DistributionConfig:
        Enabled: "true"
        Comment: "Redirect to root domain"
        PriceClass: PriceClass_100
        Aliases:
          - !Ref FromDomain
        DefaultCacheBehavior:
          TargetOriginId: PrimaryOrigin
          CachePolicyId: !Ref RedirectCachePolicy
          FunctionAssociations:
            - EventType: viewer-request
              FunctionARN: !Ref RedirectFunction
          ViewerProtocolPolicy: allow-all
        ViewerCertificate:
          AcmCertificateArn: !Ref Certificate
          SslSupportMethod: sni-only
        # The lambda prevents traffic from hitting this origin, but we need it regardless
        Origins:
          - Id: PrimaryOrigin
            DomainName: !Ref FromDomain
            CustomOriginConfig:
              OriginProtocolPolicy: http-only
              HTTPPort: 80

  RedirectCachePolicy:
    Type: AWS::CloudFront::CachePolicy
    Properties:
      CachePolicyConfig:
        Name: RedirectCachePolicy
        MinTTL: 3600
        MaxTTL: 31536000
        DefaultTTL: 86400
        ParametersInCacheKeyAndForwardedToOrigin: 
          EnableAcceptEncodingGzip: false
          CookiesConfig: 
            CookieBehavior: none
          HeadersConfig: 
            HeaderBehavior: whitelist
            Headers:
              - Origin
          QueryStringsConfig: 
            QueryStringBehavior: all

  Certificate:
    Type: AWS::CertificateManager::Certificate
    Properties:
      DomainName: !Ref FromDomain
      ValidationMethod: DNS
      DomainValidationOptions:
        - DomainName: !Ref FromDomain
          HostedZoneId: !Ref HostedZoneId

  RedirectFunction:
    Type: AWS::CloudFront::Function
    Properties: 
      Name: www_redirect
      FunctionConfig: 
        Comment: Redirects a subdomain to the root domain
        Runtime: cloudfront-js-1.0
      AutoPublish: true
      FunctionCode: !Sub |
        function handler(event) {
          var newUrl = 'https://${ToDomain}';

          // Append path
          newUrl += event.request.uri;

          // Append query string
          // - skipping because it's annoying to parse.

          return {
            statusCode: 302,
            statusDescription: '302 Redirect to root domain',
            headers:{
              "location": { "value": newUrl }
            }
          };
        };