debugging.md

Debugging

Logging

JVM

For JVM targets, the Kotlin SDK uses the slf4j logger. The build configuration can be updated to enable log output.

While any slf4j-compatible log library may be used, here is an example to enable log output from the SDK in JVM programs:

implementation("org.slf4j:slf4j-simple:1.7.30")

To view low-level request and response log output and the time of the log entry, specify this as JVM parameters to the executing program:

-Dorg.slf4j.simpleLogger.defaultLogLevel=TRACE -Dorg.slf4j.simpleLogger.showDateTime=true

The log level can be adjusted up as needed to DEBUG, INFO, WARN, or ERROR. See here for all properties for the simple logger.

Unit Tests

To enable logging in JVM unit tests, the JVM properties can be passed via the Gradle test task. Here is an example snippet from a build.gradle.kts file:

tasks.test {
    options {
        jvmArgs = listOf("-Dorg.slf4j.simpleLogger.defaultLogLevel=TRACE", "-Dorg.slf4j.simpleLogger.showDateTime=true")
    }
}

CRT Logs

JVM system properties for CRT related logs

Property	Description
aws.crt.log.level	Specify log level None, Fatal, Error, Warn, Info, Debug, Trace
aws.crt.log.destination	The destination to log to None, Stdout, Stderr, File. By default when level is not None stderr is used
aws.crt.log.filename	Redirect logs to a file

Error Metadata

The raw protocol response is usually available on exceptions if you need access to additional response details (headers, status code, etc).

try {
    ...
} catch(ex: AwsServiceException) {
    val httpResp = ex.sdkErrorMetadata.protocolResponse as? HttpResponse
    if (httpResp != null) {
        println(httpResp.headers)
        println(httpResp.body.readAll()?.decodeToString())
    }
}