Support ETag/If-None-Match when proxy_http_version is 1.1
|Reported by:||Colin Mollenhour||Owned by:||somebody|
|nginx -V:||not applicable|
If HTTP/1.1 support is specified for the proxy module using proxy_http_version (1.1.4+) it could also support cache re-validation using ETags with the upstream.
Preferably there should be an option such as proxy_cache_etag with options off,replace,append. With "append", when the server sets a new ETag the old cached data should not be removed so that subsequent upstream requests specify an If-None-Match header with multiple ETag values so that the server can specify which ETag should be used. Effectively, multiple version of the Request-URI could be cached and upstream would determine which version is to be served. With "replace" the most recently specified ETag from upstream is the only one kept in the cache.