AWS CloudFormation CloudFront CDN

Overview

Create production-ready CDN infrastructure using AWS CloudFormation templates. This skill covers CloudFront distributions, multiple origins (ALB, S3, API Gateway, Lambda@Edge, VPC Origins), CacheBehaviors, Functions, SecurityHeaders, and best practices for parameters, outputs, and cross-stack references.

When to Use

Creating CloudFront distributions with CloudFormation
Configuring origins (ALB, S3, Lambda@Edge, VPC Origins) with path patterns
Implementing caching with CacheBehaviors and Cache Policies
Configuring custom domains with ACM and SecurityHeaders
Integrating WAF with CloudFront distributions

Instructions

Follow these steps to create CloudFront distributions with CloudFormation:

1. Define Distribution Parameters

Validate before deploying:

aws cloudformation validate-template --template-body file://template.yaml
cfn-lint template.yaml

Specify domain names, ACM certificates, price class, and origin settings:

Parameters:
  DomainName:
    Type: String
    Default: cdn.example.com
    Description: Custom domain name for CloudFront distribution

  CertificateArn:
    Type: AWS::ACM::Certificate::Arn
    Description: ACM certificate ARN for HTTPS

  PriceClass:
    Type: String
    Default: PriceClass_All
    AllowedValues:
      - PriceClass_All
      - PriceClass_100
      - PriceClass_200
    Description: CloudFront price class

  OriginDomainName:
    Type: String
    Description: Domain name of the origin (ALB or S3)

2. Configure Origins

Add S3 buckets, ALBs, API Gateway, or custom origins. For S3 origins, use OAI (legacy) or OAC (recommended):

Resources:
  # S3 Bucket
  StaticBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: !Sub "static-assets-${AWS::AccountId}-${AWS::Region}"
      PublicAccessBlockConfiguration:
        BlockPublicAcls: true
        BlockPublicPolicy: true

  # Origin Access Control (recommended)
  OriginAccessControl:
    Type: AWS::CloudFront::OriginAccessControl
    Properties:
      OriginAccessControlConfig:
        Name: !Sub "${AWS::StackName}-oac"
        OriginAccessControlOriginType: s3
        SigningBehavior: always
        SigningProtocol: sigv4

3. Set Up Default Cache Behavior

Configure viewer request/response policies and caching:

Resources:
  CloudFrontDistribution:
    Type: AWS::CloudFront::Distribution
    Properties:
      DistributionConfig:
        Origins:
          - Id: S3Origin
            DomainName: !GetAtt StaticBucket.RegionalDomainName
            AccessControlId: !Ref OriginAccessControl
            S3OriginConfig:
              OriginAccessIdentity: ""
        DefaultCacheBehavior:
          TargetOriginId: S3Origin
          ViewerProtocolPolicy: redirect-to-https
          AllowedMethods:
            - GET
            - HEAD
          CachedMethods:
            - GET
            - HEAD
          Compress: true
          CachePolicyId: !Ref CachePolicy

4. Add Additional Cache Behaviors

Create path-specific caching rules for different content types:

Resources:
  ApiCachePolicy:
    Type: AWS::CloudFront::CachePolicy
    Properties:
      CachePolicyConfig:
        Name: !Sub "${AWS::StackName}-api-cache"
        DefaultTTL: 300
        MaxTTL: 600
        MinTTL: 60

  CloudFrontDistribution:
    Type: AWS::CloudFront::Distribution
    Properties:
      DistributionConfig:
        CacheBehaviors:
          - PathPattern: "/api/*"
            TargetOriginId: ApiOrigin
            CachePolicyId: !GetAtt ApiCachePolicy.Id
            AllowedMethods:
              - GET
              - HEAD
              - OPTIONS
              - PUT
              - POST

5. Configure Security Settings

Implement security headers and WAF integration:

Resources:
  SecurityHeadersPolicy:
    Type: AWS::CloudFront::ResponseHeadersPolicy
    Properties:
      ResponseHeadersPolicyConfig:
        Name: !Sub "${AWS::StackName}-security-headers"
        SecurityHeadersConfig:
          StrictTransportSecurity:
            AccessControlMaxAgeSec: 31536000
            IncludeSubdomains: true
            Override: true
          FrameOptions:
            FrameOption: DENY
            Override: true

  WAFWebACL:
    Type: AWS::WAFv2::WebACL
    Properties:
      Name: !Sub "${AWS::StackName}-waf"
      Scope: CLOUDFRONT
      DefaultAction:
        Allow: {}

6. Add CloudFront Functions

Configure functions for request/response manipulation:

Resources:
  RewritePathFunction:
    Type: AWS::CloudFront::Function
    Properties:
      Name: !Sub "${AWS::StackName}-rewrite-path"
      FunctionCode: |
        function handler(event) {
          var request = event.request;
          // Function code here
          return request;
        }
      Runtime: cloudfront-js-1.0
      AutoPublish: true

7. Configure Monitoring

Set up logging and access logs to S3:

Resources:
  AccessLogsBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: !Sub "cloudfront-logs-${AWS::AccountId}"

  CloudFrontDistribution:
    Type: AWS::CloudFront::Distribution
    Properties:
      DistributionConfig:
        Logging:
          Bucket: !Ref AccessLogsBucket
          Prefix: cloudfront-logs/
          IncludeCookies: false

8. Create Outputs

Export distribution details for cross-stack references:

Outputs:
  DistributionDomainName:
    Description: CloudFront distribution domain name
    Value: !GetAtt CloudFrontDistribution.DomainName
    Export:
      Name: !Sub "${AWS::StackName}-DistributionDomainName"

  DistributionId:
    Description: CloudFront distribution ID
    Value: !Ref CloudFrontDistribution
    Export:
      Name: !Sub "${AWS::StackName}-DistributionId"

Best Practices

Security

Always use HTTPS with minimum TLS 1.2
Implement SecurityHeaders with HSTS, XSS protection
Use WAF for protection against common attacks
Configure appropriate Access-Control for CORS
Limit origin access with OAI/OAC
Use Signed URLs for private content
Implement rate limiting
Configure geo-restrictions if needed

Performance

Use appropriate PriceClass to optimize costs
Configure Cache TTL based on content type
Enable compression (Gzip/Brotli)
Use CloudFront Functions for lightweight operations
Optimize header forwarding (do not forward unnecessary headers)
Consider Origin Shield to reduce load on origins
Use multiple origins with path patterns

Monitoring

Enable CloudWatch metrics and alarms
Configure real-time logs for troubleshooting
Monitor cache hit ratio
Configure alerts for error rate and latency
Use CloudFront reports for traffic analysis

Deployment

Use change sets before deployment
Test templates with cfn-lint
Organize stacks by lifecycle and ownership
Implement blue/green deployments with weighted aliases
Use StackSets for multi-region deployment

Template Structure

Use AWS-specific parameter types (AWS::ACM::Certificate::Arn, AWS::S3::Bucket::RegionalDomainName)
Implement parameter constraints (MinLength, MaxLength, AllowedValues, AllowedPattern)
Use Conditions for environment-specific configuration
Leverage Mappings for region-specific configuration
Apply Metadata for parameter grouping and labels
Use nested stacks for modularity

Cache Strategy

Use Cache Policies for different content types
Configure Origin Request Policies to control what's sent to origin
Set appropriate TTL values:
- Static assets: 86400-31536000 seconds (1 day to 1 year)
- API responses: 60-600 seconds (1-10 minutes)
- Dynamic content: 0 seconds (no caching)
Enable compression for text-based content
Use versioned paths for cache busting

Constraints and Warnings

ACM certificates: Must be in us-east-1 (N. Virginia) for CloudFront
Limits: Max 200 distributions per AWS account, 25 origins per distribution, 25 cache behaviors per distribution
Deployment time: CloudFront distributions take up to 30 minutes to deploy; plan accordingly
Certificate requirements: Max 100 alternate domain names per distribution; include default domain for SSL
OAI deprecation: Prefer Origin Access Control (OAC) over Origin Access Identity (OAI) for S3 origins
Lambda@Edge limits: 128MB memory, 30s timeout for viewer request/response; separate limits apply for origin requests
Change sets: Always use change sets before deploying to preview resource changes and avoid accidental deletions
Drift detection: CloudFormation does not detect drift for CloudFront distributions — manage all settings in templates

Examples

Minimal S3 Static Site Distribution

AWSTemplateFormatVersion: "2010-09-09"
Resources:
  S3Bucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: !Sub "cdn-static-${AWS::AccountId}"
      PublicAccessBlockConfiguration:
        BlockPublicAcls: true
        BlockPublicPolicy: true

  OriginAccessControl:
    Type: AWS::CloudFront::OriginAccessControl
    Properties:
      OriginAccessControlConfig:
        Name: !Sub "${AWS::StackName}-oac"
        OriginAccessControlOriginType: s3
        SigningBehavior: always
        SigningProtocol: sigv4

  CloudFrontDistribution:
    Type: AWS::CloudFront::Distribution
    Properties:
      DistributionConfig:
        Enabled: true
        DefaultRootObject: index.html
        Origins:
          - Id: S3Origin
            DomainName: !GetAtt S3Bucket.RegionalDomainName
            AccessControlId: !Ref OriginAccessControl
        DefaultCacheBehavior:
          TargetOriginId: S3Origin
          ViewerProtocolPolicy: redirect-to-https
          Compress: true
          CachePolicyId: 658327ea-f89d-4fab-a63d-7e88639e58f6
        PriceClass: PriceClass_All
        HttpVersion: http2and3

Outputs:
  DistributionDomainName:
    Value: !GetAtt CloudFrontDistribution.DomainName

Multi-Origin with Cache Behaviors

Resources:
  CachePolicyApi:
    Type: AWS::CloudFront::CachePolicy
    Properties:
      CachePolicyConfig:
        Name: !Sub "${AWS::StackName}-api"
        DefaultTTL: 300
        MaxTTL: 600
        MinTTL: 60

  CloudFrontDistribution:
    Type: AWS::CloudFront::Distribution
    Properties:
      DistributionConfig:
        Origins:
          - Id: S3Origin
            DomainName: !GetAtt StaticBucket.RegionalDomainName
            AccessControlId: !Ref OriginAccessControl
          - Id: ApiOrigin
            DomainName: !GetAtt ApiLoadBalancer.DNSName
            CustomOriginConfig:
              OriginProtocolPolicy: https-only
              HTTPPort: 80
              HTTPSPort: 443
        CacheBehaviors:
          - PathPattern: "/api/*"
            TargetOriginId: ApiOrigin
            CachePolicyId: !GetAtt CachePolicyApi.Id
            ViewerProtocolPolicy: https-only
          - PathPattern: "/static/*"
            TargetOriginId: S3Origin
            CachePolicyId: 658327ea-f89d-4fab-a63d-7e88639e58f6

References

For detailed implementation guidance, see:

template-structure.md - Complete template structure, AWS-specific parameter types, parameter constraints, SSM parameter references, metadata for parameter grouping, transform for macros, conditions for environment-specific configuration, nested stacks, and cross-stack references with export/import patterns
origins.md - Origin configuration including S3 origins with OAI/OAC, ALB origins with security groups, API Gateway origins (REST and HTTP APIs), Lambda@Edge origins, VPC origins with Global Accelerator, custom origins, and multi-origin configurations with path patterns
caching.md - Cache policies (managed, custom, images, videos), origin request policies, response headers policies, cache behaviors configuration, forwarded values (query strings, headers, cookies), cache key configuration, and TTL configuration best practices
security.md - Security headers (CSP, HSTS, XSS protection), CORS configuration, WAF integration with managed and custom rules, origin access control (OAI vs OAC), signed URLs and signed cookies, geo-restrictions, HTTPS enforcement, TLS configuration, and field-level encryption
advanced-features.md - CloudFront Functions (viewer request, viewer response, origin request), Lambda@Edge for authentication and URL rewriting, geo-restrictions, price class optimization, compression (Gzip and Brotli), real-time logs to Kinesis and S3, custom error pages, function associations, and Origin Shield configuration
constraints.md - Resource limits (200 distributions max, 25 origins max, 25 cache behaviors max), DNS and certificate constraints (ACM in us-east-1, 300 alternate domain names), operational constraints (15 invalidations max, 30 min deployment), security constraints (HTTPS, CSP, WAF), and cost considerations (data transfer, regional pricing, Lambda@Edge costs)