I get these log messages showing up

"envoy_on_request() function not found. Lua filter will not hook requests."

and I wanted to bring forward the question as to whether they should be an INFO level log message, or debug?
They seem somewhat noisy - my thinking is that most people who configure a lua filter are not surprised if they aren't hooking into either the request or response, in the cases where they only want to handle one. So what is the purpose behind this message?

Should it perhaps be a warning if BOTH functions are missing, but otherwise debug?

Secondarily, if someone was to add function envoy_on_response(_) end into all their lua filters in order to suppress this log message, does that incur any overheads when envoy is running? Does it then cause the lua filter to hook into the request/response, do nothing, and then continue?

Let me know your thoughts.

https://github.com/envoyproxy/envoy/blob/main/source/extensions/filters/http/lua/lua_filter.cc#L223-L230