porque adicionar Expire-Header a arquivos estáticos em nginX não funciona

Question

Eu tenho um único bloco de servidor no qual o meu site reside. Dentro desse bloco, adicionei um bloco location , conforme abaixo:

server {
...

location ~* \.(?:ico|css|js|gif|jpe?g|png)$ {
    expires 30d;
    add_header Pragma public;
    add_header Cache-Control "public";
    }
...
}

Quando eu verifico expirar cabeçalhos com Y! Lento nada está em cache!

NB: recarreguei meu arquivo de configuração antes de testar.

EDIT 1:

Percebi que a alteração de qualquer arquivo estático não refletirá novas alterações no navegador. Esse cache significa cache do lado do servidor? Não podemos armazenar em cache nos navegadores dos clientes?

EDIT 2:

HTTP/1.0 200 OK
Server: nginx
Date: Tue, 23 Sep 2014 07:41:20 GMT
Content-Type: image/png
Content-Length: 5597
Last-Modified: Wed, 30 Jul 2014 22:50:19 GMT
ETag: "53d976ab-15dd"
Accept-Ranges: bytes
Age: 30396
Connection: close

EDIT 3:

Configuração completa do nginX:

# You may add here your
# server {
#   ...
# }
# statements for each of your virtual hosts to this file

##
# You should look at the following URL's in order to grasp a solid understanding
# of Nginx configuration files in order to fully unleash the power of Nginx.
# http://wiki.nginx.org/Pitfalls
# http://wiki.nginx.org/QuickStart
# http://wiki.nginx.org/Configuration
#
# Generally, you will want to move this file somewhere, and start with a clean
# file but keep this around for reference. Or just disable in sites-enabled.
#
# Please see /usr/share/doc/nginx-doc/examples/ for more detailed examples.
##

server {

    # Port that the web server will listen on.
    listen 80;

    # Host that will serve this project.
    server_name localhost;

    # Useful logs for debug.
location ~* \.(ico|css|js|gif|jpe?g|png)$ {
    expires 30d;
    add_header Pragma public;
    add_header Cache-Control "public";
}
    # The location of our projects public directory.
    root /var/www/html;

    # Point index to the Laravel front controller.
    index index.php;

    location / {

        # URLs to attempt, including pretty ones.
        try_files $uri $uri/ /index.php?$query_string;

    }

    # Remove trailing slash to please routing system.
    if (!-d $request_filename) {
        rewrite ^/(.+)/$ /$1 permanent;
    }

    # PHP FPM configuration.
    location ~* \.php$ {
            fastcgi_pass unix:/var/run/php5-fpm.sock;
            fastcgi_index index.php;
            fastcgi_split_path_info ^(.+\.php)(.*)$;
            include /etc/nginx/fastcgi_params;
            fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
    }

    # We don't need .ht files with nginx.
    location ~ /\.ht {
            deny all;
    }

   location ~ ^/(themes/\w+/views) {
        deny  all;
    }  

    #avoid processing of calls to unexisting static files by yii
    location ~ \.(js|css|png|jpg|gif|swf|ico|pdf|mov|fla|zip|rar)$ {
        try_files $uri =404;
    } 


}
    # Only for nginx-naxsi used with nginx-naxsi-ui : process denied requests
    #location /RequestDenied {
    #   proxy_pass http://127.0.0.1:8080;    
    #}

    #error_page 404 /404.html;

    # redirect server error pages to the static page /50x.html
    #
    #error_page 500 502 503 504 /50x.html;
    #location = /50x.html {
    #   root /usr/share/nginx/html;
    #}

    # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
    #
    #location ~ \.php$ {
    #   fastcgi_split_path_info ^(.+\.php)(/.+)$;
    #   # NOTE: You should have "cgi.fix_pathinfo = 0;" in php.ini
    #
    #   # With php5-cgi alone:
    #   fastcgi_pass 127.0.0.1:9000;
    #   # With php5-fpm:
    #   fastcgi_pass unix:/var/run/php5-fpm.sock;
    #   fastcgi_index index.php;
    #   include fastcgi_params;
    #}

    # deny access to .htaccess files, if Apache's document root
    # concurs with nginx's one
    #
    #location ~ /\.ht {
    #   deny all;
    #}



# another virtual host using mix of IP-, name-, and port-based configuration
#
#server {
#   listen 8000;
#   listen somename:8080;
#   server_name somename alias another.alias;
#   root html;
#   index index.html index.htm;
#
#   location / {
#       try_files $uri $uri/ =404;
#   }
#}


# HTTPS server
#
#server {
#   listen 443;
#   server_name localhost;
#
#   root html;
#   index index.html index.htm;
#
#   ssl on;
#   ssl_certificate cert.pem;
#   ssl_certificate_key cert.key;
#
#   ssl_session_timeout 5m;
#
#   ssl_protocols SSLv3 TLSv1;
#   ssl_ciphers ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv3:+EXP;
#   ssl_prefer_server_ciphers on;
#
#   location / {
#       try_files $uri $uri/ =404;
#   }
#}

    

Answer 1

O motivo é que você tem dois blocos que correspondem aos arquivos de imagem:

location ~* \.(?:ico|css|js|gif|jpe?g|png)$ {
location ~ \.(js|css|png|jpg|gif|swf|ico|pdf|mov|fla|zip|rar)$ {

Isso significa que o nginx usa apenas o último para seus arquivos de imagem.

Você precisa alterar as declarações location desta forma:

location ~* \.(?:ico|css|js|gif|jpe?g|png)$ {
    expires 30d;
    add_header Pragma public;
    add_header Cache-Control "public";
    try_files $uri =404;
}

location ~ \.(?:swf|pdf|mov|fla|zip|rar)$ {
    try_files $uri =404;
}

Agora os arquivos de imagem correspondem apenas ao primeiro bloco, por isso é usado.

Considere também adicionar o cabeçalho Expires , se quiser controlar o tempo que os navegadores armazenam em cache os arquivos, sem revalidá-los do servidor.