ajp_cache
The `ajp_cache` directive enables caching of responses from an AJP server in NGINX.
Description
The ajp_cache directive is part of the NGINX AJP module, which facilitates proxying requests to AJP-compatible servers, such as Apache Tomcat. When enabled, this directive specifies a shared memory zone for caching responses from the backend AJP server. It allows responses to be stored in memory, thereby improving response time for repeated requests and reducing load on the backend server. To use this directive effectively, it must be accompanied by a previously defined ajp_cache_path directive that specifies the cache's settings and storage path.
This directive can be used within the http, server, or location contexts, providing flexibility regarding where caching is applied in the NGINX configuration. The caching behavior can be further fine-tuned using related directives, such as ajp_cache_key, to customize cache keys based on request parameters, or ajp_cache_min_uses to determine how many times a response must be accessed before it is cached. Without proper configuration of these parameters, administrators may face issues such as cache flooding or ineffective caching, leading to degraded performance instead of the intended improvements.
Config Example
http {
ajp_cache my_cache;
ajp_cache_path /var/cache/nginx/ajp_cache levels=1:2 keys_zone=my_cache:10m inactive=60m;
server {
listen 80;
location / {
ajp_pass my_backend;
ajp_cache on;
}
}
}Ensure that ajp_cache_path is defined before using ajp_cache.
Cache key configuration should be clear to avoid unintentional cache misses or excess loading.