Nginx – How to set Nginx ignore Pragma: no-cache

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The correct method of doing this is to construct a cache key by using nginx $arg_... variables. $arg_... will contain query string parameters. So in the above example we would use $arg_parameter and $arg_parameter2 within the cache key.

The result in the nginx.conf looks like:

http {
  ...
    server {
      location / {
         ...
         proxy_cache_key $scheme$proxy_host$uri$is_args$arg_parameter$arg_parameter2;
      }
    }
  ...
}

Note that querystring parameter containing an hyphen (dash), such as data-* parameters, do not work with the $arg_paramName syntax. A workaround using Lua can be found in this post.

You could use proxy_cache_bypass.

proxy_cache_bypass  $http_cache_control;

This will cause nginx to fetch a fresh copy of the document in the presence of the Cache-Control header in the HTTP request from the client.

Note that the resulting response from the backend is still eligible for caching. If you want to disqualify it from being cached, use the same arguments with the proxy_no_cache directive, too.

Source: http://wiki.nginx.org/HttpProxyModule#proxy_cache_bypass

If you specifically want to only bypass the cache when the client has Cache-Control: max-age=0 in the headers (e.g. to explicitly not support another variant, Cache-Control: no-cache, which is actually supposedly a stronger preference for a fresh copy of the page than max-age=0 is), then you can use the following, which I won't recommend due to such limitation:

set $cc_ma  0;
if ($http_cache_control = "max-age=0") {    # honour ⌘R, ignore ⇧⌘R (yes, bad idea!)
    set $cc_ma  1;
}
proxy_cache_bypass  $cc_ma;

BTW, there's also Pragma: no-cache, which this obviously won't account for, although in my limited set of experiments, it's always accompanied by a Cache-Control: no-cache, so, the original one-liner would probably do the best job.

As a note, SeaMonkey sends Cache-Control: max-age=0 when you click Reload or ⌘R, and Pragma: no-cache\r\nCache-Control: no-cache when you Shift Reload or ⇧⌘R.