Cache filter
This filter should be configured with the type URL
type.googleapis.com/envoy.extensions.filters.http.cache.v3.CacheConfig
.This filter doesn’t support virtual host-specific configurations.
When the cache is enabled, cacheable requests are only sent through filters in the upstream_http_filters chain and not through any filters in the regular filter chain that are further upstream than the cache filter, while non-cacheable requests still go through the listener filter chain. It is therefore recommended for consistency that only the router filter should be further upstream in the listener filter chain than the cache filter.
The HTTP Cache filter implements most of the complexity of HTTP caching semantics.
For HTTP Requests:
HTTP Cache respects request’s
Cache-Control
directive. For example, if request comes withCache-Control: no-store
the request won’t be cached, unless ignore_request_cache_control_header is true.HTTP Cache wont store HTTP HEAD Requests.
For HTTP Responses:
HTTP Cache only caches responses with enough data to calculate freshness lifetime as per RFC7234.
HTTP Cache respects
Cache-Control
directive from the upstream host. For example, if HTTP response returns status code 200 withCache-Control: max-age=60
and novary
header, it will be cached.HTTP Cache only caches responses with status codes: 200, 203, 204, 206, 300, 301, 308, 404, 405, 410, 414, 451, 501.
HTTP Cache delegates the actual storage of HTTP responses to implementations of the HttpCache
interface. These implementations can
cover all points on the spectrum of persistence, performance, and distribution, from local RAM caches to globally distributed
persistent caches. They can be fully custom caches, or wrappers/adapters around local or remote open-source or proprietary caches.
Currently the only available cache storage implementation is SimpleHTTPCache.
Example configuration
Example filter configuration with a SimpleHttpCache
cache implementation:
29 http_filters:
30 - name: "envoy.filters.http.cache"
31 typed_config:
32 "@type": "type.googleapis.com/envoy.extensions.filters.http.cache.v3.CacheConfig"
33 typed_config:
34 "@type": "type.googleapis.com/envoy.extensions.http.cache.simple_http_cache.v3.SimpleHttpCacheConfig"
See also
- Envoy Cache Sandbox
Learn more about the Envoy Cache filter in the step by step sandbox.