Edit me

With the cli option --baseline or the detekt-gradle-plugin closure-property baseline you can specify a file which is used to generate a baseline.xml. It is a file where ignored code smells are defined.

The intention of CurrentIssues is that only new code smells are printed on further analysis. The ManuallySuppressedIssues can be used to write down false positive detections (instead of suppressing them and pollute your code base).

The ID node has the following structure: <RuleID>:<Codesmell_Signature>.
When adding a custom issue to the xml file, make sure the RuleID should be self-explaining. The Codesmell_Signature is not printed to the console but can be retrieved from the txt output file when using the --report txt:path/to/report cli flag.

<SmellBaseline>
  <ManuallySuppressedIssues>
    <ID>CatchRuntimeException:Junk.kt$e: RuntimeException</ID>
  </ManuallySuppressedIssues>
  <CurrentIssues>
    <ID>NestedBlockDepth:Indentation.kt$Indentation$override fun procedure(node: ASTNode)</ID>
    <ID>TooManyFunctions:LargeClass.kt$io.gitlab.arturbosch.detekt.rules.complexity.LargeClass.kt</ID>
    <ID>ComplexMethod:DetektExtension.kt$DetektExtension$fun convertToArguments(): MutableList&lt;String&gt;</ID>
  </CurrentIssues>
</SmellBaseline>

Gradle

If you are using the gradle-plugin run the detektBaseline task to generate yourself a baseline.xml. This will create one baseline file per Gradle module. As this might not be the desired behavior for a multi module project, think about implementing a custom meta baseline task:

Groovy DSL
subprojects {
    detekt {
        // ...
        baseline = file("${rootProject.projectDir}/config/baseline.xml")
        // ...
    }
}

task detektProjectBaseline(type: io.gitlab.arturbosch.detekt.DetektCreateBaselineTask) {
    description = "Overrides current baseline."
    ignoreFailures.set(true)
    parallel.set(true)
    buildUponDefaultConfig.set(true)
    setSource(files(rootDir))
    config.setFrom(files("$rootDir/config/detekt/detekt.yml"))
    baseline.set(file("$rootDir/config/detekt/baseline.xml"))
    include("**/*.kt")
    include("**/*.kts")
    exclude("**/resources/**")
    exclude("**/build/**")
}
Kotlin DSL
subprojects {
    detekt {
        // ...
        baseline = file("${rootProject.projectDir}/config/baseline.xml")
        // ...
    }
}

val detektProjectBaseline by tasks.registering(DetektCreateBaselineTask::class) {
    description = "Overrides current baseline."
    buildUponDefaultConfig.set(true)
    ignoreFailures.set(true)
    parallel.set(true)
    setSource(files(rootDir))
    config.setFrom(files("$rootDir/config/detekt/detekt.yml"))
    baseline.set(file("$rootDir/config/detekt/baseline.xml"))
    include("**/*.kt")
    include("**/*.kts")
    exclude("**/resources/**")
    exclude("**/build/**")
}

FAQ

Be aware that auto formatting cannot be combined with the baseline. The signatures for a ; for example would be too ambiguous.