Invalidate cache for static files?

[Mansoor Peerbhoy]

Hi

Have you tried suppressing the Last-Modified response header ?
Usually, when a web server serves a static page, it uses the mtime of the file to send back the Last-Modified response header.

When the browser loads the static file, let's say at time X, it may get back the response header Last-Modified: Y

Then, subsequently, when the browser wants the page again, it sends the If-Modified-Since request header, containing X
And, if the file has not been modified in the interval since X, then the web server sends back the HTTP not modified response (304)

Does NGINX send back the Last-Modified header for static resources ? I guess it should.
Also, if NGINX allows you to suppress a response header on the way out, then you should use that config directive to suppress the Last-Modified header.

I believe that should cause the browser to reload the resource every time, though one can't be sure about these things

Regards,
Mansoor

----- "Denis Arh" <denis at arh.cc> wrote:

| From: "Denis Arh" <denis at arh.cc>
| To: nginx at sysoev.ru
| Sent: Monday, July 21, 2008 8:31:16 PM GMT +05:30 Chennai, Kolkata, Mumbai, New Delhi
| Subject: Re: Invalidate cache for static files?
|
| Would it help moving them into a different folder instead of appending
|  
| query string?
| 
| Sent from my iPhone
| 
| On 21.7.2008, at 16:55, Tit Petric <black at scene-si.org> wrote:
| 
| >
| >
| > Maxim Dounin wrote:
| >> Hello!
| >>
| >> On Mon, Jul 21, 2008 at 01:57:06PM +0100, Phillip B Oldham wrote:
| >>
| >>> What would be the simplest way to invalidate browser cache of  
| >>> static  files served by nginx?
| >>>
| >>> For instance, we have a website which is in active development. We
|  
| >>> get a  reasonable amount of traffic, but we often get complaints 
| 
| >>> when we update  the live files because some browsers are working 
| 
| >>> with a mix of fresh  (live) and stale (cached) js/css files. We'd 
| 
| >>> like to inform/force  browsers that the file is new and should be 
| 
| >>> updated.
| >>
| >> Just use normal web development practices, e.g. add "?v=<version>"
| >> to js/css urls.  Nothing special, nginx is just web server.
| > I've tried this before, it is problematic since cache doesn't behave
|  
| > correctly and in some cases browsers or even caching proxies in  
| > front of backend servers never cache the resource, because they  
| > percieve the link as dynamic.
| >
| > Having unique urls, like I suggested in the previous email, solves 
| 
| > theese problems. Also, you can then set the Expires & Cache-control 
| 
| > headers for static content far in the future and encourage browser 
| 
| > caching, since you have an effective method of always reloading them
|  
| > without fail. Caches and browsers will keep such objects, while the 
| 
| > suggested sollution with the "?v=version" will not be cached on many
|  
| > of them, since they percieve the url as dynamic and always try a  
| > reload, ignoring possible Expires & Cache-control headers.
| >
| > For a small setup, where you don't care about resources, your  
| > sollution is mostly fine, but is problematic in the real world with 
| 
| > tens of thousands of users.
| >
| > BR
| >