Nginx: bug using if in location, how do I rectify

I am using nginx in reverse proxy mode. In my server section I have this code to set expire and cache control of my static files.

     location ~* ^.+\.(css|js|png|gif)$ {
         access_log off;
         expires max;
         add_header Cache-Control public;
         if (!-f $request_filename) {
           proxy_pass  http://localhost:82;
         }

     }

This is quite obviously creating issues. Can someone help me correct this code to use try_files or rewrite?

Solution 1:

There are at least 2 techniques.

error_page

Before the introduction of try_files directive the common method was to intercept error code 404 and process the request with a named location, e.g.

location ~* \.(css|js|png|gif)$ {
  access_log off;
  expires max;
  add_header Cache-Control public;
  error_page 404 = @upstream;
}

try_files

The equivalent using try_files would be

location ~* \.(css|js|png|gif)$ {
  access_log off;
  expires max;
  add_header Cache-Control public;
  try_files $uri @upstream;
}

And the named location is the same for both scenarios:

location @upstream {
  proxy_pass http://localhost:82;
}