Performance recommendations don't detect CloudFront as CDN

[semenko]

The performance recommendations don’t seem to correctly identify CloudFront embedded resources.

For example:

WebPageTest

Use a CDN for all static assets: 75/100
FAILED - http://d2ob8jnie7eh8t.cloudfront.net/s/states/va.png
FAILED - http://d2ob8jnie7eh8t.cloudfront.net/s/CC_BY_NC_SA-flickr_umhealthsystem.jpg
FAILED - http://d2ob8jnie7eh8t.cloudfront.net/s/CC_BY_NC_SA-flickr_manachar.jpg
FAILED - http://d2ob8jnie7eh8t.cloudfront.net/s/CC_BY_NC-flickr_ericparker.jpg
FAILED - http://d2ob8jnie7eh8t.cloudfront.net/s/license_by_sa_80x15.png

CDN’s Used:
www.vaccinatedoctors.org : Amazon CloudFront
[snip]

It detects the whole site as being on CloudFront, but not those images.

Looking specifically at the requests:

WebPageTest

They’re definitely via CloudFront:

GET /s/CC_BY_NC_SA-flickr_manachar.jpg HTTP/1.1
Accept: image/png, image/svg+xml, image/*;q=0.8, /;q=0.5
Referer: http://www.vaccinatedoctors.org/
Accept-Language: en-US
X-Download-Initiator: image=“doc 0400; speculative; html tokenizer 5CC0; html lookahead 1:F550”
User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0; PTST 2.365)
Accept-Encoding: gzip, deflate
Host: d2ob8jnie7eh8t.cloudfront.net
Connection: Keep-Alive

Response Headers:
HTTP/1.1 200 OK
Content-Type: image/jpeg
Content-Length: 3958
Connection: keep-alive
Date: Fri, 09 Aug 2013 16:13:15 GMT
Cache-Control: public, max-age=2628000
Last-Modified: Sat, 16 Feb 2013 23:56:23 GMT
ETag: “7f314b40af95f23b379eb9256650934d”
Server: AmazonS3
Age: 246680
Via: 1.0 83cd944526daec64262fa3b420e82133.cloudfront.net (CloudFront)
X-Cache: Hit from cloudfront

[pmeenan]

Hmm, thanks. I think you may have hit an edge condition where the browser didn’t do a DNS lookup for that domain because the base page was CNAME’d to it and my code was depending on the DNS lookups to identify the CDN.

I just added the cloudfront via header as a fallback for detection. It will probably be a few days before it is live on the production system but it should be fixed soon.