- CDN is a content delivery network is a system of distributed servers (network) that deliver webpages and other web content to a user based on the geographic locations of the user, the origin of the webpage and a content delivery server.
- Amazon CloudFront, you use key pairs to create signed URLs for private content, such as when you want to distribute restricted content that someone paid for.
- IAM users can’t create CloudFront key pairs. You must log in using root credentials to create key pairs.
- CloudFront Key Terminologies
- Edge location – This is the location where the content will be cached This is different than the AWS Region/AZ (Availability Zone).
- We can see the available Edge location on AWS site.
- Origin – This is the origin of the actual files, that CDN will distribute. This can be a S3 Bucket, an EC2 instance, an Elastic Load Balancer or Route53.
- Distribution – This is the name given to CDN which has a collection of Edge Location.
- Web Distribution – This used only for the Websites
- RTMP – used for the Media files.
- CDN Example
- The requester will first hit the edge location and then the Edge location will contact the actual server.
- The data will be cached at the Edge location till TTL and then will be passed to the requester.
- The first request will be delayed one as it goes around through the requester – Edge – Server, but the next request will be faster as the data will be directly fetched from the Edge location.
CDN Usage
- CDN can be used to deliver, the entire website, including static, dynamic, Streaming and Interactive content.
- Request will be automatically routed to the nearest Edge location.
- CDN is optimized to work with different AWS services,
- S3
- Elastic Load balancer
- EC2
- Route53
- It also works seamlessly with non-AWS origin servers, which stores the original, definitive versions of your files.
- Edge location are for both Read and Write operations i.e. we can put an object to an Edge location.
- Every object cached has TTL, to clear the cache, it will be a chargeable service.
- CDN provides two different types,
- RTMP
- Web Distribution
- To restrict the user, select option pre-signed URL or signed cookies. This will restrict the user access to pre-verified URL and sharing the content will be restricted.
- WAF (Web Application Firewall), this blocks the Cross scripting, SQL injections.
- We can have shared SSL certificate or the dedicated one assigned to domain.
- Geo restriction allows us to whitelist or blacklist the countries. We can either blacklist or whitelist. We cannot use both at the same time.
- Create Invalidation is used to remove the object/content from the Edge location cache.
We can force to load the content through CloudFront, accessing the content directly through the S3 DNS URL will throw an error.