Fastcgi_cache_key and empty $content_type in cache

Have a strange behavior of fastcgi cache, the variable $content_type
does not passes to the cache KEY, configuration:

location ~ .php$ {
fastcgi_cache cache;
fastcgi_cache_key
“$content_type|$request_method|$is_args|$host|$request_uri|$http_referer”;
fastcgi_cache_valid any 60m;
fastcgi_cache_use_stale error timeout invalid_header http_500
http_503;
fastcgi_ignore_headers “Set-Cookie” “Cache-Control” “Expires”;
fastcgi_pass_header “Set-Cookie”;

    fastcgi_pass   127.0.0.1:8000;
    fastcgi_index  index.php;
    fastcgi_connect_timeout 60;
    fastcgi_send_timeout 180;
    fastcgi_read_timeout 180;
    fastcgi_buffers 4 128k;

    fastcgi_buffer_size 128k;

    fastcgi_intercept_errors on;

    fastcgi_param  SCRIPT_FILENAME

$document_root$fastcgi_script_name;
fastcgi_param REMOTE_USER $remote_user;
fastcgi_param QUERY_STRING $query_string;
fastcgi_param REQUEST_METHOD $request_method;
fastcgi_param CONTENT_TYPE $content_type;
fastcgi_param CONTENT_LENGTH $content_length;
fastcgi_param SCRIPT_NAME $fastcgi_script_name;
fastcgi_param REQUEST_URI $request_uri;
fastcgi_param DOCUMENT_URI $document_uri;
fastcgi_param DOCUMENT_ROOT $document_root;
fastcgi_param SERVER_PROTOCOL $server_protocol;
fastcgi_param GATEWAY_INTERFACE CGI/1.1;
fastcgi_param SERVER_SOFTWARE nginx/$nginx_version;
fastcgi_param REMOTE_ADDR $remote_addr;
fastcgi_param REMOTE_PORT $remote_port;
fastcgi_param SERVER_ADDR $server_addr;
fastcgi_param SERVER_PORT $server_port;
fastcgi_param SERVER_NAME $server_name;

    fastcgi_param SCRIPT_FILENAME

/var/www/site_folder$fastcgi_script_name;
}

But when I look into cache-file, the KEY field does not contain the
content-type:

KEY:
|GET|?|site_name|/system/files/imagecache/50x50/iconimage.png|http://site_name/

Content-Type: image/png

As you see the content-type is visible in cache-file body, but it is not
visible in the KEY field, it’s just empty there. Does anybody knows why
this happens?

Thank you for your advices.

Posted at Nginx Forum:
http://forum.nginx.org/read.php?2,194424,194424#msg-194424

Hello!

On Fri, Apr 29, 2011 at 06:22:39AM -0400, namesys wrote:

Have a strange behavior of fastcgi cache, the variable $content_type
does not passes to the cache KEY, configuration:

[…]

visible in the KEY field, it’s just empty there. Does anybody knows why
this happens?

Content-Type header you see in body is response content type
(available as $upstream_http_content_type variable). It can’t be
used in cache key though as it’s not known before we have a
response.

Variable $content_type is request content type. It’s empty in
most cases as requests usually doesn’t have any content.

Maxim D.