Jsdelivr: Add a response header to show current CDN

[SukkaW]

QUANTIL has its specific response header: x-via.
Cloudflare has its specific response header: cf-ray, server: cloudflare
Stackpath has its specific response header: server: NetDNA-cache/2.2
Fastly has its specific response header: x-served-by, but since jsDelivr uses Fastly as middle load balancer and cache layer, for cdn.jsdelivr.net it is not unique.

I suggest adding a response header like 'x-jsdelivr-cdn: fastly' 'x-jsdelivr-cdn: stackpath' 'x-jsdelivr-cdn: cloudflare', and if no 'x-jsdelivr-cdn' header is given, then the request could have hit QUANTIL. I believe it could be helpful when debugging.

[MartinKolarik]

This would have to be done by each provider separately and I'm not sure if all of them support setting custom headers. The correct detection logic is this though:

• server: cloudflare - Cloudflare
• server: NetDNA-cache/2.2 - StackPath
• x-via - Quantil
• none of the above - Fastly

[SukkaW]

@MartinKolarik

Stackpath and Fastly support custom header:

• https://support.stackpath.com/hc/en-us/articles/360001417983-Getting-Started-with-Custom-CDN-EdgeRules
• https://docs.fastly.com/en/guides/adding-or-modifying-headers-on-http-requests-and-responses

Cloudflare doesn't mentioned custom headers in their docs but I wonder if you can ask Cloudflare Engineer to help setup a custom response header.

QUANTIL doesn't support custom response headers.

[MartinKolarik]

Closing this as it wouldn't work with quantil and the detection is still possible as per my previous comment.