How to set project loglevel

[hughesadam87]

Hi,

Thanks for putting this library together. In using kotlin, I was putoff by the long/complex answers to the simple question "how do you log in kotlin (http://stackoverflow.com/questions/34416869/idiomatic-way-of-logging-in-kotlin)".

I'm using Klogging as follows:

    companion object: KLogging()

     init {
        logger.info("NewsArticle initialized: " + this)
      }

This works nicely, but when I do logger.debug, my IntelliJ IDEA run console doesn't show any output. Do you know how I could set the console logger to debug or trace levels? Is this an IDE setting, or can it be set in the call to KLogging()?

[oshai]

I saw a similar question on SO: http://stackoverflow.com/questions/43146977/how-to-configure-kotlin-logging-logger
Let me know if that clear things.

[oshai]

updated the frequently asked questions

[sschuberth]

Despite the FAQ entry I believe we desperately need a concrete example on how to set the log level when using e.g. logback as the logger implementation. I have in build.gradle:

dependencies {
    // Use logback-classic as the logger for kotlin-logging / slf4j as it allow changing the log level at runtime.
    compile 'io.github.microutils:kotlin-logging:1.4.5'
    compile 'ch.qos.logback:logback-classic:1.2.3'
}

And in my main.kt:

internal val log = KotlinLogging.logger {}

// ...

if (!debug) {
    // Logback's default log level is DEBUG, so change that to INFO unless --debug is given.
    (log as ch.qos.logback.classic.Logger).level = ch.qos.logback.classic.Level.INFO
}

But that gives

Exception in thread "main" java.lang.ClassCastException: mu.internal.LocationAwareKLogger cannot be cast to ch.qos.logback.classic.Logger

So how am I supposed to access the logger implementation via kotlin-logging in order to call the logger implementation-specific code to set the log level?

[oshai]

I think I understand the issue you mention. What I suggest is to add to the KLogger interface a method - getUnderlyingLogger() or something similar that will provide the underlying log implementation which can be casted to ch.qos.logback.classic.Logger in the case of logback.
Another alternative is to use xml configuration like explained here: https://logback.qos.ch/manual/configuration.html

What do you think about this solution?

[sschuberth]

getUnderlyingLogger() or something similar that will provide the underlying log implementation

That would probably work, although it seems a tad inconvenient. That is, slightly less convenient than being able to just casting the main class.

Another alternative is to use xml configuration

But that does not seem to be usable if I need to change the log level at runtime triggered by external events (potentially multiple times).

[oshai]

I can add that, probably a property underlyingLogger is more appropriate. will you use that if such exists?

[sschuberth]

will you use that if such exists?

Well, given that I just migrated to slf4k because of that missing feature, probably not right away, but I'll certainly give it a try in one of my next projects.

[oshai]

ok, I will add that to 1.4.6.

…

On Tue, Jul 11, 2017 at 9:45 PM, Sebastian Schuberth < ***@***.***> wrote: will you use that if such exists? Well, given that I just migrated to slf4k because of that missing feature, probably not right away, but I'll certainly give it a try in one of my next projects. — You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub <#20 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ACj0QYANW6kVho2ylzmT74LCLZ3MidSlks5sM8LPgaJpZM4M0wmA> .

[oshai]

1.4.6 released

[ObserverOfTime]

This works pretty well with underlyingLogger:

import ch.qos.logback.classic.Level
import ch.qos.logback.classic.Logger

var mu.KLogger.level
    get() = (underlyingLogger as Logger).level
    set(value) { (underlyingLogger as Logger).level = value }

logger.level = Level.DEBUG
logger.level //=> Level.DEBUG