Caching Made Easy Part 2: Pass The Stack

server {
   listen   [::]:80;
   access_log off;
   error_log  /dev/null crit;
   server_name yourwebasset.com;
 
   # only needed if serving static content
   root /var/www/htdocs;
 
   location / {
      # Go ahead and serve static content.
      # If you don't want to serve static content,
      # then change location @fastpath to /
      # and remove this location declaration.
      try_files $uri @fastpath;
   }
 
   #Magic lies within
   location @fastpath {
 
      # If memcached can't find an entry, it returns a 404.
      # We intercept 404 pages and pass them along to
      # our predefined location.  The location has access
      # to all the same variables as before and doesn't know
      # that a prior 404 was generated other than our debug
      # variable.
      error_page 404 = @appstack;
 
      # I like to use these for debugging. This is the default
      # reason for passing on to @appstack.  Variables are
      # preserved through location passing
      set $reason "MISS";
 
      # This is only passed on to the client if we actually get a hit,
      # otherwise the add_header is thrown away when we
      # pass processing onto @appstack
      # Remember the far future cache control headers from Part I?
      add_header X-Cache-debug "HIT";
      add_header Expires "Tue, 1 Jun 1979 12:01:00 GMT";
      add_header Cache-Control "must-revalidate, post-check=0, pre-check=0";
 
      # Check to see if someone passed in ?nocache=1
      # This is not required
      # but good for testing your app
      if ( $args ~* "nocache=1" ) {
          set $reason "nocache override";
          return 404;
      }
 
      # Only GET/HEAD requests are safe
      if ( $request_method !~ ^(GET|HEAD)$) {
          set $reason "method not safe";
          return 404;
      }
 
      # From Part I we set a unique authentication
      # token in the cookies. Here we check and see if
      # this token is set and, if so, skip memcache for
      # authenticated users.
      if ( $http_cookie ~* "AUTH_UID" ) {
          set $reason "authenticated";
          return 404;
      }
 
      # If you want to cache URL arguments, use $request_uri below
      # otherwise, use $uri. Using $request_uri will result in more
      # cache misses, but caches potentially more complex pages. 
      # Arguments are preserved in the key
      # Uncomment this conditional when using $uri
      #if ( $args ) { 
      #   set $reason "arguments";
      #    return 404;
      #}
      set $memcached_key prefix-$scheme://$host$uri;
      memcached_pass 127.0.0.1:11211;
 
      # Since we can't store any complex data, we blindly return the value.
      # Make sure you don't gzip any data that you store in memcached.
      # Memcached also already fastlz's anything you store in there.
      default_type text/html;
      charset utf-8;
   }
 
 
   location ~ \.php$ {
      # protect your php files (or any files)
      error_page 592 = @appstack;
      return 592;
   }
 
   # if you are using fastcgi, you can use that 
   # here instead of the proxy_pass items
   location @appstack {
 
      proxy_pass  http://127.0.0.1:8080;
      proxy_redirect off;
      proxy_set_header   Host             $host;
      proxy_set_header   X-Real-IP        $remote_addr;
      proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
      proxy_max_temp_file_size 0;
 
      client_max_body_size       10m;
      client_body_buffer_size    128k;
      proxy_connect_timeout      90;
      proxy_send_timeout         90;
      proxy_read_timeout         90;
 
      proxy_buffer_size          4k;
      proxy_buffers              4 32k;
      proxy_busy_buffers_size    64k;
      proxy_temp_file_write_size 64k;
 
      add_header X-Cache-debug $reason;
   }
}