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CloudFront

  • Content Distribution Network (CDN) creates cached copies of your website at various Edge locations around the world

  • Content Delivery Network (CDN)

    • A CDN is a distributed network of servers which delivers web pages and content to users based on their geographical location, the origin of the webpage and a content delivery server

      • Can be used to deliver an entire website including static, dynamic and streaming

      • 216 points of presence globally

      • DDoS protection since it is a global service. Integrates with AWS Shield and AWS WAF

      • Requests for content are served from the nearest Edge Location for the best possible performance

CloudFront Core Components

  • Origin

    • The location where all of original files are located. For example an S3 Bucket, EC2 Instance, ELB or Route53

  • Edge Location

    • The location where web content will be cached. This is different than an AWS Region or AZ

  • Distribution

    • A collection of Edge locations which defines how cached content should behave

CloudFront Distributions

  • A distribution is a collection of Edge Location. You specific the Origin eg. S3, EC2, ELB, Route53
  • It replicates copies based on your Price Class
  • There are two types of Distributions
    1. Web (for Websites)
    2. RTMP (for streaming media)
  • Behaviors
    • Redirect to HTTPs, Restrict HTTP Methods, Restrict Viewer Access, Set TTLs
  • Invalidations
    • You can manually invalidate cache on specific files via Invalidations
  • Error Pages
    • You can serve up custom error pages eg 404
  • Restrictions
    • You can use Geo Restriction to blacklist or whitelist specific countries

Lambda@Edge

  • Lambda@Edge functions are used to override the behavior of request and responses

  • Lambda@Edge lets you run Lambda functions to customize the content that CloudFront delivers, executing the functions in AWS locations closer to the viewer.

  • The functions run in response to CloudFront events, without provisioning or managing servers. You can use Lambda functions to change CloudFront requests and responses at the following points:

  • The 4 Available Edge Functions

    1. Viewer Request
      • When CloudFront receives a request from a Viewer
    2. Origin request
      • Before CLoudFront forwards a request to the origin
    3. Origin response
      • When cloudfront receives a response from the origin
    4. Viewer response
      • Before CLoudFront returns the response to the viewer

CloudFront Protection

  • By Default a Distribution allows everyone to have access
  • Original Identity Access (OAI)
    • A virtual user identity that will be used to give your CloudFront Distribution permission to fetch a private object
  • Inorder to use Signed URLs or Signed Cookies you need to have an OAI
  • Signed URLs
    • (Not the same thing as S3 Presigned URL)
      • A url with provides temporary access to cached objects
  • Signed Cookies
    • A cookie which is passed along with the request to CloudFront. The advantage of using a Cookie is you want to provide access to multiple restricted files. eg. Video Streaming