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chx
Asked: 2014-08-20 02:13:23 +0800 CST

How to disable proxy cache when query string is empty?

  • 772

With nginx I have

server {
  listen 1.2.3.4:80
  proxy_cache_valid       200 302 5m;
  location /  {
    try_files $uri @upstream;
    root $root;
  }
}

When I go http://example.com/foobar it generates a redirect to http://example.com/foobar?filter_distance=50&... which is visitor dependent so I would like to not cache this redirect. I need to bypass cache when the query string is empty. I am a bit lost because location /foobar will match both.

nginx

2 Answers

  1. Best Answer

    I added 

    map $request_uri $nocache {
  /foobar 1;
}

    to the http section and

    proxy_cache_bypass $nocache;
proxy_no_cache $nocache;

    to the server section. This seems to be working.

    • 2

  2. You should use the proxy_cache_bypass and proxy_no_cache directives like this:

    set $nocache 0;

if ($arg_filter_distance = "") {
    set $nocache 1;
}

proxy_cache_bypass $nocache;
proxy_no_cache $nocache;

    Definition of proxy_no_cache from nginx documentation

    Defines conditions under which the response will not be saved to a cache. If at least one value of the string parameters is not empty and is not equal to “0” then the response will not be saved:

    Here we test if the filter_distance GET parameter is empty. If it is, we set $nocache to 1, and then the proxy_cache_bypass and proxy_no_cache directives will get active.

    You can add other GET parameters similary, for example $arg_filter_type, if you have a filter_type GET parameter.

    • 1