How to log stack trace using kotlin.logging?

Question

I am using kotlin.logging as my logging framework for an application.

I would like to be able to log the stack trace in a much more readable way (maybe JSON format):

I am doing the following, but it results in a very verbose/unreadable format:

logger.error("Exception caught in handleIllegalArgumentsException: $e", e.printStackTrace())

when logging the Throwable exception only (see below), it does not show the stack trace:

logger.error("Exception caught in handleIllegalArgumentsException: $e") 

Answer 1

You should be able to get stack trace using the following way.

logger.error(e) {"Exception caught in handleIllegalArgumentsException}

Answer 2

For the people getting here through a google search:

Since Kotlin 1.4 Throwable has an extension method that allows you to get the Stack Trace as a String, which basically does what is suggested by other answers.

/**
 * Returns the detailed description of this throwable with its stack trace.
 *
 * The detailed description includes:
 * - the short description (see [Throwable.toString]) of this throwable;
 * - the complete stack trace;
 * - detailed descriptions of the exceptions that were [suppressed][suppressedExceptions] in order to deliver this exception;
 * - the detailed description of each throwable in the [Throwable.cause] chain.
 */
@SinceKotlin("1.4")
public actual fun Throwable.stackTraceToString(): String {
    val sw = StringWriter()
    val pw = PrintWriter(sw)
    printStackTrace(pw)
    pw.flush()
    return sw.toString()
}

This means the original e.printStackTrace() just needs to be changed into e.stackTraceToString()

Like so:

logger.error("Exception caught in handleIllegalArgumentsException: ${e.stackTraceToString()}") 

Answer 3

If you want the logger to print the exception stacktrace:

try {
    ...
} catch (e: Exception) {
    logger.error("Exception caught:", e)
}

If you want the string itself (for further manipulation), you can use what @Михаил Нафталь suggested:

try {
    ...
} catch (e: Exception) {
    val stacktrace = StringWriter().also { e.printStackTrace(PrintWriter(it)) }.toString().trim()
    logger.error("Exception caught: $stacktrace")
}

Both these methods will print the whole stacktrace in the logs, for example:

16:41:50.528 [main] ERROR org.myorg.MyClass - Exception caught:
java.lang.IllegalArgumentException: Argument X was not allowed.
    at org.myorg.MyClass.func (MyClass.kt:124)
    at java.base/java.lang.Thread.run(Thread.java:834)
    etc...

I know it's not answering to what is asked in the question text, but it's answering to the question title. As this post was the first suggestion I got when googling how to log stacktraces with Kotlin, I thought this might help others.