srcache_request_cache_control
The `srcache_request_cache_control` directive manages caching by controlling how client requests influence cache behavior through specific HTTP headers.
Description
The srcache_request_cache_control directive is part of the NGINX ngx_srcache module, which provides a mechanism for caching subrequests. This directive allows configuration of how the Cache-Control headers from requests influence the caching logic of stored responses. When enabled, it instructs NGINX to honor the Cache-Control headers (no-store, no-cache, private, etc.) sent by clients in their requests, thus controlling whether the responses can be cached or not. This offers flexibility and nuance in managing cache behavior at a granular level, making it suitable for applications that need varying caching strategies based on client request attributes.
When the directive is set to 'on', it enables the processing of the Cache-Control request headers. This is particularly useful in environments with dynamic content delivery, as it allows responses to be cached or not based on client-specific conditions. For example, if a client makes a request with a Cache-Control: no-store header, then the corresponding response will not be cached, allowing for always fresh retrieval of the resource. Conversely, if no such headers are present, standard caching rules apply, thus reducing server load and improving response times.
Config Example
http {
server {
location / {
srcache_request_cache_control on;
proxy_pass http://backend;
}
}
}Ensure that srcache_request_cache_control is compatible with other caching directives being used in conjunction; otherwise, unexpected caching behavior may occur.
When enabled, this directive can cause some responses to not be cached as expected if clients frequently use headers like no-cache.
Test the caching behavior thoroughly in a staging environment before deploying to production, especially with a mix of static and dynamic content.