Nova has an in-memory object cache to accelerate and offload your web servers. This is available on SSL termination and HTTP groups only.
Small object caching allows you to offload some of the static content from your application servers. They can then better perform their primary duty - delivering the application.
By default Nova allows a total of 128MB of objects to be cached in memory, and expires stale objects after 240 seconds (4 minutes). The maximum cachable object size is 256KB.
It's important to know that this is designed for high performance small object caching, not to store large infrequently used files. Typically what you want to see in production is that your stylesheets, javascript, images, and the like can be served directly from Nova.
Nova caching has several restrictions on when it will decide to cache and serve an object. These are listed below.
| Name | Description |
|---|---|
| Size | The object must be under 256KB |
| HTTP Status | The HTTP status for the request must be a 200 code |
| Vary | The response does not have a Vary header |
| Content Length | The response must have a Content-Length header |
| Cacheable | The response must not have a Cache-Control: no-cache header |