JWT authn: Logging for cache refresh for JWKS

[aniketmasule]

Title: Logging for cache refresh for JWKS

Description:
I am using jwt filter for authentication, using remote_jwks to provide remote jwks uri and using cache_duration to configure cache refresh interval.
I have a query regarding following scenario:
When rotating signing keys, we begin by advertising the new key's on remote URI. Then, we activate it, and new tokens are signed with these new keys. However, I'm unable to determine if the new key has been cached successfully before activating new keys. Is there a method to log the cached keys or somehow check the cache?
Additionally, I cannot obtain tokens with the new key until I activate the new signing keys.

Relevant Links:
https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_filters/jwt_authn_filter#config-http-filters-jwt-authn

[phlax]

cc @TAOXUY @lizan

[aniketmasule]

Hi @TAOXUY @lizan, Kindly let me know if you have any inputs on above query?