slf4j LogAppender

[justcoon]

slf4j log appender

• key-values - LogAppender.appendKeyValue - logged into MDC
• cause - LogAppender.appendCause - as throwable, Cause transformed into FiberFailure
• slf4j logger name extracted from Trace

open question -

• do we need rootLogLevel in private def slf4jLogger(rootLoggerName: Trace => String, rootLogLevel: LogLevel, format: LogFormat): ZLogger[String, Unit] ? - in general, log level setup is in specific logger configuration
• LogFormat combinators/composition - in current design, it is not clear, where specific LogFormat part will be "inserted" (message, MDC, cause ...), there is a question, if it should not be more clear in LogFormat itself
• should we allow custom definition for log logger name (maybe by annotation as it was in version 1) ?

related to: #485, #453, #445

[987Nabil]

@justcoon I guess this is also the reason, why updating to 2.0.1 broke our slf4j + logstash json logging?
Any plan when this would be fixed? Or do you need some help?

And to answer your last question: Yes we definitely need the ability to set logger names. In the 2xRC version we did this with the rootLoggerName: Trace => String

[justcoon]

hello @987Nabil,

in relation to

2.0.1 broke our slf4j + logstash json logging

do you mean update from 2.0.0 -> 2.0.1? If yes, maybe it will be good if you open some ticket with details (like logstash configuration, zio logging slf4j setup - log format ..., code snippet, if possible)

in case of logger name - SLF4J.getLoggerName
basically if there is trace zio.logging.example.LivePingService.ping(PingService.scala:22), then logger name is zio.logging.example.LivePingService - service class name

in my opinion, this is reasonable default logger name resolution, based on trace
but at the other side, i think, have option to say, what is logger name, can be very usefull

[jdegoes]

Let's not modify the appendKeyValue. Instead, generate an anonymous LogAppender that will simply produce string for any possible combination of operations.

[justcoon]

@jdegoes: previously removed function def appendKeyValue(key: String, appendValue: LogAppender => Unit) of LogAppender- returned back

[987Nabil]

hello @987Nabil,

in relation to

2.0.1 broke our slf4j + logstash json logging

do you mean update from 2.0.0 -> 2.0.1? If yes, maybe it will be good if you open some ticket with details (like logstash configuration, zio logging slf4j setup - log format ..., code snippet, if possible)

I'll do.

in case of logger name - SLF4J.getLoggerName basically if there is trace zio.logging.example.LivePingService.ping(PingService.scala:22), then logger name is zio.logging.example.LivePingService - service class name

in my opinion, this is reasonable default logger name resolution, based on trace but at the other side, i think, have option to say, what is logger name, can be very usefull

Maybe it is a reasonable default, but in my opinion having it configurable is a must. There are architecture guidelines out there in the wild, that require special logger names for access logging for example. One reason for something like this can be, that messages with a certain name get treated in your logging tool based on logger names.
Also it is available in every (JVM) logging lib out there and I do not see any reason to break this pattern.

[987Nabil]

@justcoon I opened #489 and would not be surprised, if it is related.

[justcoon]

latest changes

• previously removed function def appendKeyValue(key: String, appendValue: LogAppender => Unit) of LogAppender- returned back
• added SLF4J.loggerName aspect, for custom slf4j logger name
• layers, with LogLevel are deprecated
• there are scala-2 tests only, for slf4j, as there is issue with Trace in scala-3 (Align Traces zio#7177)
• updated documentation and examples