Cloudfront

AWS content delivery network (CDN)

Edge Locations

Over 100 AWS data centers geographically distributed across the globe, with the following services offered and synced through ALL OF THEM: Route53, Cloudfront, WAF, Shield and Lambda@Edge

Cloudfront Origins

• Source of content (static and dynamic)

• Can be an:

  • S3 bucket

  • ELB

  • Any public HTTP endpoint (web distribution)

• Live Video Streaming and VOD

• RTMP Distribution (Flash Media Files)

Essentials

• Global CDN which delivers content to users from the nearest edge location.

• Retrieves content from origins

• Distributions (web or RTMP)

  • Define origins for content (static and dynamic)

  • Integrate with Route53 for alternate CNAMEs

    • Allows you to create a URL like cdn.nicacton.com that works with a distribution

  • Cache behaviors

    • PATH pattern (images*.jpg)

    • Min, Max, Default TTL

    • Query String forwarding and caching

    • HTTP Methods (GET, POST, PUT, HEAD, etc...)

Updating Cached Files

• Caching is done based off the cache key.

• In order to serve a new version of an object, either create a new object with a new name or create an "invalidation" on the Cloudfront distribution based off the object name.

• "Invalidations" can be costly

• Set TTL=0

Security

• SSL Certificates can be used

• End-to-end HTTPs

• AWS WAF Integration

• Distribute Private Content

  • S3

    • Limit access to Origin Access Identity (OAI)

      • Modified in Bucket policy

  • Signed URL or Signed Cookie

    • Expiration

    • Restrict by IP

    • Trusted Signers (Cloudfront Key Pairs)

• Geo Restriction

Performance

• Regional Caches

  • Save content ejected from cache close to Edge location

• Point entire domain to Cloudfront to speed up dynamic content

  • Content optimizations

  • Dynamic objects are still cached

• CloudFront performance can be affected by:

  • File size and type of file

  • Having to remake the request from the Edge location to the origin.

    • Downloading the object from origin takes time.

    • As well writing it to cache and responding to the end user request.

    • The more requests that have to go to the origin, the higher the load is on your source. Which can also cause latency and load performance issues.

  • Query strings (request to the origin to serve a specific object) reduce cache "hits":

    • cdn.nicacton.com/?querythis=querythat

    • Reduces performance because query strings are often unique so it reduces the cache hits and require "work" to forward to the origin location.

• Cloudfront Performance increased by:

  • Longer cache periods increase performance (less frequent request to the source).