Gzip compression with nginx

Question

In my nginx.conf I have:

gzip              on;
gzip_static       on;
gzip_buffers      16 8k;
gzip_comp_level   9;
gzip_http_version 1.0;
gzip_min_length   1000;
gzip_types        text/plain text/css image/x-icon image/bmp image/png image/gif image/jpeg image/jpg application/json application/x-javascript text/javascript;
gzip_vary         on;
gzip_proxied any;

So, if I fetch the headers of a picture on my server:

spiroo@glamdring:~$ curl -I http://static.mysite.com/g/pics/big_6e1855d844ebca560379139e75942f669655f.jpeg
HTTP/1.1 200 OK
Server: nginx
Date: Thu, 04 Apr 2013 13:00:20 GMT
Content-Type: image/jpeg
Content-Length: 5336
Last-Modified: Mon, 25 Mar 2013 13:28:02 GMT
Expires: Fri, 04 Apr 2014 13:00:20 GMT
Cache-Control: max-age=31536000
Pragma: public
Cache-Control: public, must-revalidate, proxy-revalidate
Accept-Ranges: bytes

But if I turn off the gzip compression in nginx.conf, I have exactly the same result on the Content-Length.

What am I doing wrong?

Thanks in advance.

PS: Just to be clear, I have the nginx last release, and I am behind a proxy (haproxy).

EDIT ==>

I have the same problem with the CSS. I understand jpeg are already compressed. Of crouse, when I switch gzip on/off I restart nginx.

This is my fetch from the headers of a css file. I have the same Content-Lenght with or without gzip compression.

spiroo@glamdring:~$ curl -I http://static.mysite.com/css/9a7f503b.css
HTTP/1.1 200 OK
Server: nginx
Date: Thu, 04 Apr 2013 14:21:50 GMT
Content-Type: text/css
Content-Length: 203088
Last-Modified: Tue, 02 Apr 2013 11:34:39 GMT
Vary: Accept-Encoding
Expires: Fri, 04 Apr 2014 14:21:50 GMT
Cache-Control: max-age=31536000
Pragma: public
Cache-Control: public, must-revalidate, proxy-revalidate
Accept-Ranges: bytes

And this is the nginx configuration for my statics files:

server {
server_name     static.mysite.com;
root /home/www/mysite/current/web;

location / {
    return 404;
}

location ~ \.(?:jpg|jpeg|js|css|gif|png|swf|ico|pdf)$ {
    expires        365d;
    access_log     off;
    add_header Pragma public;
    add_header Cache-Control "public, must-revalidate, proxy-revalidate";
}

}

Answer 1

curl doesn't Accept-Encoding: gzip by default. You will need to either use -H "Accept-Encoding: gzip,deflate" to get curl to request gzip or better yet, use --compressed so curl will know to decompress the result.

Answer 2

Pictures (jpg/gif etc) are already compressed. So you don't need to (and shouldn't try to) compress them on the web server.

Here is an example of what I compress:

gzip_types        text/html text/plain text/css application/x-javascript text/xml application/xml application/xml+rss text/javascript image/x-icon image/bmp;