Tag: cache control

Proxying static content sometimes requires to modify the expire directive on the proxy server, but sometimes it may just need to pass the origin expire directive. What if the “expires” is defined in the server section and ones need to pass through the value from the origin by the proxy server?

Simply switch off the expires by “expires off”. It will disable an earlier definition in the block it is used and the proxy answer to the client will include the origin header for the cache control.

It won’t disable the cache control meaning to add no-cache in proxy answer to the client. So if it is used “expires” in a block and a pass-through from the origin is required, just make a location block with “expires off”:

        server {
                listen          10.10.10.10:443 ssl http2;
                server_name     srv1.example.com;

                ssl_certificate  /etc/ssl/nginx/srv1.example.com.chain.crt;
                ssl_certificate_key /etc/ssl/nginx/srv1.example.com.key;

                resolver 8.8.8.8;

                client_max_body_size 12m;

                expires         -1;
                root            /mnt/storage/web/root;
                access_log      /mnt/storage/web/logs/srv1.example.com;
                error_log       /mnt/storage/web/logs/srv1.example.com warn;

                location / {
                        #proxy
                        proxy_buffer_size   128k;
                        proxy_buffers   4 256k;
                        proxy_busy_buffers_size   256k;
                        proxy_buffering off;
                        proxy_read_timeout 600;
                        proxy_send_timeout 600;
                        proxy_store off;
                        proxy_cache off;
                        proxy_redirect off;
                        proxy_no_cache $cookie_nocache $arg_nocache $arg_comment;
                        proxy_no_cache $http_pragma $http_authorization;
                        proxy_cache_bypass $cookie_nocache $arg_nocache $arg_comment;
                        proxy_cache_bypass $http_pragma $http_authorization;

                        proxy_pass https://https_backend;
                        proxy_http_version 1.1;
                        proxy_set_header Connection "";
                        proxy_set_header Host $host;
                        proxy_set_header        X-Real-IP-EXAMPLE       $remote_addr;
                        proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
                }

                location ~* \.jpeg {
                        expires off;
                        #proxy
                        proxy_buffer_size   128k;
                        proxy_buffers   4 256k;
                        proxy_busy_buffers_size   256k;
                        proxy_buffering off;
                        proxy_read_timeout 600;
                        proxy_send_timeout 600;
                        proxy_store off;
                        proxy_cache off;
                        proxy_redirect off;
                        proxy_no_cache $cookie_nocache $arg_nocache $arg_comment;
                        proxy_no_cache $http_pragma $http_authorization;
                        proxy_cache_bypass $cookie_nocache $arg_nocache $arg_comment;
                        proxy_cache_bypass $http_pragma $http_authorization;
                        proxy_ignore_headers "Expires" "Cache-Control";


                        proxy_pass https://https_backend;
                        proxy_http_version 1.1;
                        proxy_set_header Connection "";
                        proxy_set_header Host $host;
                        proxy_set_header        X-Real-IP-EXAMPLE       $remote_addr;
                        proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
                }

                 location ~* \.(jpg|gif|png|css|mcss|js|mjs|woff|woff2)$ {
                        expires 30d;
                        #proxy
                        proxy_buffer_size   128k;
                        proxy_buffers   4 256k;
                        proxy_busy_buffers_size   256k;
                        proxy_buffering off;
                        proxy_read_timeout 600;
                        proxy_send_timeout 600;
                        proxy_store off;
                        proxy_cache off;
                        proxy_redirect off;
                        proxy_no_cache $cookie_nocache $arg_nocache $arg_comment;
                        proxy_no_cache $http_pragma $http_authorization;
                        proxy_cache_bypass $cookie_nocache $arg_nocache $arg_comment;
                        proxy_cache_bypass $http_pragma $http_authorization;

                        proxy_pass http://http_backend;
                        proxy_http_version 1.1;
                        proxy_set_header Connection "";
                        proxy_set_header Host $host;
                        proxy_set_header        X-Real-IP-EXAMPLE       $remote_addr;
                        proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
                }
        }

The above sample configuration defines 3 location blocks for 3 different “expires” cases:

1. Uses the server block “expires -1” – proxy for dynamic code such as proxy site application code. No caching.
2. Uses the location block .jpeg “expires off” – the proxy will pass-through the value from the origin server. Any value from the origin.
3. Uses the location block .(gif|png|css|mcss|js|mjs|woff|woff2) “expires 30d” – it will set +30 days expire header no matter of the origin value. Origin server value is replaced by the today +30 days in the future cache cache header.