Cache filter

  • This filter should be configured with the type URL type.googleapis.com/envoy.extensions.filters.http.cache.v3.CacheConfig.

  • v3 API reference

  • v3 SimpleHTTPCache API reference

  • This filter doesn’t support virtual host-specific configurations.

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 with Cache-Control: no-store the request won’t be cached.

  • 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#calculating.freshness.lifetime.

  • HTTP Cache respects Cache-Control directive from the upstream host. For example, if HTTP response returns status code 200 with Cache-Control: max-age=60 and no vary 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:

http-cache-configuration.yaml
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.cache.simple_http_cache.v3.SimpleHttpCacheConfig"

See also

Envoy Cache Sandbox

Learn more about the Envoy Cache filter in the step by step sandbox.