ktlint-gradle-plugin

Gradle wrapper for pinterest/ktlint

Installation

Available on:

• Gradle Plugin Portal
• Maven Central

Apply the plugin

plugins {
    id("io.github.usefulness.ktlint-gradle-plugin") version "{{version}}"
}

(Optional) Managing ktlint version with Renovate/Dependaot

Given the plugin is just a wrapper and follows its own release cycle, it may a good practice to manually control ktlint tool version. One can achieve it by defining full ktlint version dependency and passing resolved ktlint version to the ktlint extension. Version Catalog example:

[versions]
ktlint = "x.y.z"

[libraries]
ktlint-cli = { module = "com.pinterest.ktlint:ktlint-cli", version.ref = "ktlint" } 

+ then

ktlint {
    ktlintVersion = libs.versions.ktlint.get()
}

Compatibility

plugin version	min gradle version	min ktlint version
0.11.0+	8.5	1.0.0
0.7.0+	8.0	1.0.0
0.5.0+	7.6	1.0.0
0.4.0+	7.6	0.50.0
0.3.0+	7.6	0.49.0
0.1.0+	7.6	0.48.0

Features

• Supports Kotlin Gradle plugins:
  • JVM
  • Multiplatform
  • Android
  • JS
• Supports .kt and .kts files
• Leverages latest Gradle APIs (cacheable, incremental tasks using Gradle Worker API)
• Configurable reporters

Tasks

When your project uses one of the supported Kotlin Gradle plugins, the plugin adds these tasks:

• ./gradlew formatKotlin: format Kotlin source code according to ktlint rules or warn when auto-format not possible.

• ./gradlew lintKotlin: report Kotlin lint errors and by default fail the build.

Also check becomes dependent on lintKotlin.

Granular tasks are added for each source set in the project: formatKotlinSourceSet and lintKotlinSourceSet.

Configuration

Options can be configured in the ktlint extension:

ktlint {
    ignoreFailures = false
    reporters = ["checkstyle", "html", "json", "plain", "sarif"]
    experimentalRules = true
    disabledRules = ["no-wildcard-imports", "experimental:annotation", "your-custom-rule:no-bugs"]
    ktlintVersion = "2.0.0-SNAPSHOT"
    chunkSize = 50
    baselineFile.set(file("config/ktlint_baseline.xml"))
    ignoreFilesUnderBuildDir = true
}

• ignoreFailures - makes the LintTask tasks always pass

• reporters - defines enable reporters for all tasks.

• experimentalRules - enables rules from ktlint Experimental ruleset.

• disabledRules - can include an array of rule ids you wish to disable

• ktlintVersion There is a basic support for overriding ktlint version, but the plugin doesn't guarantee backwards compatibility with all ktlint versions. Errors like java.lang.NoSuchMethodError: or com/pinterest/ktlint/core/KtLint$Params can be thrown if provided ktlint version isn't compatible with the latest ktlint apis.

• chunkSize - defines how many files will be processed by a single gradle worker in parallel

• baselineFile - points at location of baseline file containing known offenses that will be ignored during lintKotlin task execution

• ignoreFilesUnderBuildDir - This allows to ignore generated sources. This is a workaround for https://youtrack.jetbrains.com/issue/KT-45161. Setting the value to false restores default behavior and will run ktlint against all sources returned by KGP

• editorConfigValidation - One of None, PrintWarningLogs, BuildFailure.

  • Currently, this only validates if any of the typical editorconfig location contain root=true entry. This is highly recommended to ensure the builds are deterministic across machines

Customizing Tasks

The formatKotlinSourceSet and lintKotlinSourceSet tasks inherit from SourceTask so you can customize includes, excludes, and source.

tasks.named("lintKotlinMain") {
    exclude("com/example/**/generated/*.kt")
}

Note that exclude paths are relative to the package root.

Advanced

By default, Gradle workers will use 256MB of heap size. To adjust this setting use:

import io.github.usefulness.tasks.KtlintWorkTask

tasks.withType(KtlintWorkTask).configureEach {
    workerMaxHeapSize.set("512m")
}

Custom Rules

You can add custom ktlint RuleSets using the ktlintRuleSet configuration dependency:

dependencies {
    ktlintRuleSet(files("libs/my-custom-ktlint-rules.jar"))
    ktlintRuleSet(project(":ktlint-custom-rules"))
    ktlintRuleSet("org.other.ktlint:custom-rules:1.0")
    ktlintRuleSet("io.nlopez.compose.rules:ktlint:0.3.3")
}

Credits

YourKit supports open source projects with innovative and intelligent tools for monitoring and profiling Java and .NET applications. YourKit is the creator of YourKit Java Profiler, YourKit .NET Profiler, and YourKit YouMonitor.