H2o: logging handler

[Jxck]

I wrote mruby handler for formatting/controlling access log.
but I need to add mruby-handler-file directive to every tons of path: in h2o conf.

it seems better to allow adding handler to access log directive, and apply every request/response under that scope.

usecase:

• adding all request header into acccesslog
• formatting values into json/ltsv etc via handler
• routing/rotating log file from handler

[yannick]

hi @Jxck
most of the stuff you mentioned can already be done but might be slightly under documented.
rotating logfiles should done via pipe, i recently tried to improve the docs here a bit:
https://github.com/h2o/h2o/pull/1528

formating the logs via json can already be done via escape: json

definitly logging all headers should be possible but isn't. iirc i once opened a ticket but can't find it right now. currently i do this hack in mruby:

headers = JSON.dump(env.find_all{|k,v| k.start_with?("HTTP_")})
[200, {  "x-fallthru-set-MRB_HEADERS" => headers }, [result]]

and then log via:

access-log: 
  path: /dev/stdout
  format: '{ "requestHeaders": %{MRB_HEADERS}e }'
  escape: json

i dont think your idea of calling mruby code for every call just to tamper with the logs make sense, it would be too expensive.

[Jxck]

the point of my issue is not how to write a handler, but how to apply to path.
as I wrote

but I need to add mruby-handler-file directive to every tons of path: in h2o conf.

and

it would be too expensive.

thats depends on usecase.
logger already applies to ever req/res to the server if you enable access-log.

[yannick]

@Jxck it's not really clear to me what the problem is then.

could you maybe explain your current work around and make a sample config on how you think it could be done in a better way?

[kazuho]

Talked with @Jxck and agreed that it would make sense to have a logging directive that allows us to log all the request headers (possibly concatenated with \n) or response headers.

[Jxck]

@kazuho looking forward to see them !

[yannick]

@kazuho
would be also great if it there would be a json mode as either an object or array of arrays.
i am currently also logging them via mruby, but its ugly as they are not in their original format

[Jxck]

any updates ?