Cache Promote Plugin

The cache_promote plugin provides a means to control when an object should be allowed to enter the cache. This is orthogonal from normal Cache-Control directives, providing a different set of policies to apply. The typical use case for this plugin is when you have a very large data set, where you want to avoid churning the ATS cache for the long tail content.

All configuration is done via remap.config, and the following options are available:


The promotion policy. The values lru and chance are supported.


The sampling rate for the request to be considered

If --policy is set to lru the following options are also available:


The minimum number of hits before promotion.


The size (number of entries) of the LRU.

These two options combined with your usage patterns will control how likely a URL is to become promoted to enter the cache.


These two examples shows how to use the chance and LRU policies, respectively:

map \ @pparam=--policy=chance @pparam=--sample=10%

map \ @pparam=--policy=lru \
  @pparam=--hits=10 @pparam=--buckets=10000

Note --sample is available for all policies and can be used to reduce pressure under heavy load.