Skip to main content

Logger context items

You can add context items to loggers, that will be included in every log event emitted by them. Context items can be added to both Klogger and NoCoLogger instances.

This can be useful for passing coroutine context information into non-coroutine code.

Defining logger context items​

When creating a logger, you can pass one or more context items as pairs.

class MainService(processState: String) {
    private val logger = noCoLogger<MainService>("processState" to processState)

    fun process() {
        // Emitted log events include processState
        logger.info("start process()")
        // do stuff
    }
}

Copying context items from other loggers​

You can copy context items from one logger to another.

class MainService(processState: String) {
    private val logger = logger<MainService>("processState" to processState)

    suspend fun process() {
        // Emitted log events include processState
        logger.info("start process()")
        val subprocessState = doStuff()
        val subService = SubService(subprocessState, logger)
        subService.process()
    }
}

class SubService(subprocessState: String, parentLogger: BaseLogger) {
    private val logger = noCoLogger<SubService>(parentLogger, "subprocessState" to subprocessState)

    fun process() {
        // Emitted log events include processState and subprocessStatue
        logger.info("start process()")
        // do stuff
    }
}