S3 + Cloudfront + Route53 奇怪的缓存问题

Question

I have a static website using S3, Cloudfront and Route53. I had version 1 and now I updated to version 2.

• If I view the website using the S3 endpoint ( http://abc.s3-website-eu-west-1.amazonaws.com/ ) I see version 2.
• If I use the Cloudfront endpoint ( https://xyz.cloudfront.net/ ) I see version 2 again.
• If I use the domain I have configured in Route53 (A record pointing to the cloudfront distribution) I see version 1. I have not setup any TTL for the DNS records (default behavior) and this has been going on for ~1 week now.

---

Some extra checks:

dig A xyz.cloudfront.net and dig A mydomain.com point to the same IPs.

And the output of curl is describing the previous situation (version 1) where mydomain.com was configured to point to www.example.com . Now I have it pointing directly to the cloudfront distribution

curl -sD - https://example.com -o /dev/null
HTTP/1.1 302 Moved Temporarily
Content-Length: 0
Connection: keep-alive
Server: CloudFront
Location: https://www.example.com/
X-Cache: Miss from cloudfront
Via: 1.1 qwe.cloudfront.net (CloudFront)
...

curl -sD - https://xyz.cloudfront.net -o /dev/null
HTTP/2 200
content-type: text/html
content-length: 537
date: Fri, 18 Nov 2022 20:35:41 GMT
last-modified: Tue, 15 Nov 2022 10:09:03 GMT
etag: "..."
server: AmazonS3
x-cache: Miss from cloudfront
via: 1.1 bla.cloudfront.net (CloudFront)
...

Is there anything else I could check to find out what is misconfigured?

Answer 1

The DNS server (Route53) and the TTL on those DNS records are entirely irrelevant here. Those have nothing to do with content caching.

Your curl commands show your requests are being routed to different CloudFront edge nodes ( qwe.cloudfront.net and bla.cloudfront.net ).

It appears that one of those nodes had served a request for your website before, so it had a cached version stored, which it is still serving when you make new requests that hit that CloudFront edge node now. The other node didn't have a cached version stored, so when your request hit it, it went back to the origin (S3) and pulled in the latest version.

This is pretty much the expected behavior of CloudFront, or any other CDN, when you publish new content on your origin server without notifying the CDN that it needs to clear the old cached content. You need to tell CloudFront to invalidate the cache , which will cause it to remove the cached version of your content from all edge locations.