AWSTemplateFormatVersion: 2010-09-09

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#  Parameters                                                            #
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Parameters:
  PrimaryEndpoint:
    Type: String
  SecondaryEndpoint:
    Type: String

Resources:
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#  CloudFront::CachePolicy                                               #
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  1hCachePolicy:
    Type: AWS::CloudFront::CachePolicy
    Properties:
      CachePolicyConfig:
        Comment: Cache for 1h
        Name: !Ref AWS::StackName
        DefaultTTL: 360
        MaxTTL: 360
        MinTTL: 360
        Name: 1h
        ParametersInCacheKeyAndForwardedToOrigin:
          CookiesConfig:
            CookieBehavior: none
          EnableAcceptEncodingBrotli: false
          EnableAcceptEncodingGzip: false
          HeadersConfig:
            HeaderBehavior: whitelist
            Headers:
              - x-forwarded-for
          QueryStringsConfig:
            QueryStringBehavior: whitelist
            QueryStrings:
              - allowed_query_string_param

##########################################################################
#  CloudFront::Distribution                                              #
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  CloudfrontDistribution:
    Type: AWS::CloudFront::Distribution
    Properties:
      DistributionConfig:
        #  CNAMEs: # Aliases A complex type that contains information about CNAMEs (alternate domain names), if any, for this distribution.
        PriceClass: PriceClass_100
        IPV6Enabled: true
        HttpVersion: http2
        OriginGroups: #https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/high_availability_origin_failover.html
          Items:
            - Id: Failover
              FailoverCriteria: 
                StatusCodes: #403, 404, 500, 502, 503, 504
                  Items:
                    - 502 # Bad Gateway Exception
                    - 503 # Service Unavailable Exception
                    - 504 # Endpoint Request Timed-out Exception
                  Quantity: 3
              Members: 
                Items: 
                  - OriginId: Primary
                  - OriginId: Secondary
                Quantity: 2
          Quantity: 1
        Origins:
          - Id: Primary
            DomainName: !Ref PrimaryEndpoint
            OriginPath: /api
            CustomOriginConfig:
              HTTPSPort: 443
              OriginProtocolPolicy: https-only
              OriginSSLProtocols: 
                - TLSv1.2
          - Id: Secondary
            DomainName: !Ref SecondaryEndpoint
            OriginPath: /api
            CustomOriginConfig:
              HTTPSPort: 443
              OriginProtocolPolicy: https-only
              OriginSSLProtocols: 
                - TLSv1.2
        Enabled: true
        CacheBehaviors:
          - AllowedMethods:
              - GET
              - HEAD
            CachedMethods:
              - GET
              - HEAD
            Compress: true
            PathPattern: /api
            TargetOriginId: Failover
            ViewerProtocolPolicy: redirect-to-https
            CachePolicyId: !Ref 1hCachePolicy
          - AllowedMethods:
              - GET
              - HEAD
            CachedMethods:
              - GET
              - HEAD
            Compress: true
            PathPattern: /api/?allowed_query_string_param*
            TargetOriginId: Failover
            ViewerProtocolPolicy: redirect-to-https
            CachePolicyId: !Ref 1hCachePolicy
        DefaultCacheBehavior:
          AllowedMethods:
            - GET
            - HEAD
          CachedMethods:
            - GET
            - HEAD
          Compress: true
          TargetOriginId: Primary
          ViewerProtocolPolicy: redirect-to-https
          CachePolicyId: !Ref 1hCachePolicy

Outputs:
  DistributionDomainName:
    Description: "Distribution domain name"
    Value: !GetAtt CloudfrontDistribution.DomainName
    Export:
      Name: DistributionDomainName