I have found repeating 404 errors caused by the request https://www.exampe.com/.well-known/traffic-advice by “Chrome Privacy Preserving Prefetch Proxy” bot so I read several papers:
- https://developer.chrome.com/blog/private-prefetch-proxy/
- https://github.com/buettner/private-prefetch-proxy
- https://www.iana.org/assignments/well-known-uris/well-known-uris.xhtml
After I didn’t read this one 🙂
I decided to put recommended directive
[{
"user_agent": "prefetch-proxy",
"google_prefetch_proxy_eap": {
"fraction": 1.0
}
}]to the file “traffic-advice” in .well-known directory. No more 404 errors, hooray.
File without extension with hybrid json MIME type – why so complicated?
If it were that simple, this article wouldn’t exist so… I froze on an unusual place: the MIME type.
Documentation recommends delivering suffixless file with a hybrid json MIME type application/trafficadvice+json. Why so complicated?
Robrwo summarized it well in this Github issue so it’s enough just to quote him:
Adding a custom MIME type “application/trafficadvice+json” basically means that a special configuration for this file needs to be added to the web server configuration.
If the URL path was simply “/.well-known/traffic-advice.json” then it would have a reasonable MIME type based on the file extension, and there would be less work for site maintainers.
Ideally, website maintainers would simply add a file and let the web server serve it with the appropriate MIME type. Instead, this will require special configuration just to handle a special case, which can be a barrier to adoption.
So answer on my question “how I should return application/trafficadvice+json MIME type for .well-known/traffic-advice on my website without writing an extra script or alter my nginx configs” is none.
How to deliver application/trafficadvice+json MIME type for Apache or Nginx?
After creating of the file without extension Apache solution is to edit the main .htaccess file with these lines:
RewriteRule "^/.well-known/traffic-advice$" - [T=application/trafficadvice+json,END]Nginx solution (ehm, my own snippet) depending on your stack may looks from the most simplest:
# Private Prefetch Proxy
# https://developer.chrome.com/blog/private-prefetch-proxy/
location /.well-known/traffic-advice {
types { } default_type "application/trafficadvice+json; charset=utf-8";
}to more advanced like this:
# Private Prefetch Proxy
# https://developer.chrome.com/blog/private-prefetch-proxy/
location /.well-known/traffic-advice {
types { } default_type "application/trafficadvice+json; charset=utf-8";
alias /var/www/html/.well-known/traffic-advice;
allow all;
}Final tests
After command service nginx reload either use this traffic-advice checkup tool or wget to download the https://www.example.com/.well-known/traffic-advice in order to see proper application/trafficadvice+json MIME type and the best of all: no 404.
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