Add Kotlin app with Spring Boot 3 and coroutines

.editorconfig

@@ -8,7 +8,7 @@ max_line_length = 199
 tab_width = 4
 ij_continuation_indent_size = 4
 
-[*.java]
+[*.{java,kt}]
 ij_java_imports_layout = *,|,java.**,javax.**,|,$*
 ij_java_align_multiline_parameters = true
 ij_java_blank_lines_after_class_header = 1
@@ -30,8 +30,8 @@ ij_java_keep_simple_blocks_in_one_line = true
 ij_java_keep_simple_classes_in_one_line = false
 ij_java_keep_simple_lambdas_in_one_line = true
 ij_java_keep_simple_methods_in_one_line = true
-ij_java_names_count_to_use_import_on_demand = 101
-ij_java_class_count_to_use_import_on_demand = 101
+ij_java_names_count_to_use_import_on_demand = 201
+ij_java_class_count_to_use_import_on_demand = 201
 ij_java_packages_to_use_import_on_demand = java.awt.*, javax.swing.*
 ij_java_prefer_longer_names = true
 ij_java_space_after_closing_angle_bracket_in_type_argument = false

build.gradle.kts

@@ -9,7 +9,7 @@ description = "Experiments with Java"
 
 allprojects {
     group = "io.github.mfvanek"
-    version = "0.3.3"
+    version = "0.4.0"
 
     repositories {
         mavenLocal()

buildSrc/build.gradle.kts

@@ -14,4 +14,8 @@ dependencies {
     implementation("de.thetaphi:forbiddenapis:3.9")
     implementation("com.github.spotbugs.snom:spotbugs-gradle-plugin:6.1.7")
     implementation("org.gradle:test-retry-gradle-plugin:1.6.2")
+    val kotlinVersion = "2.0.21"
+    implementation("org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlinVersion")
+    implementation("org.jetbrains.kotlin:kotlin-allopen:$kotlinVersion")
+    implementation(libs.detekt)
 }

buildSrc/settings.gradle.kts

@@ -0,0 +1,9 @@
+rootProject.name = "sb-ot-demo-conventions"
+
+dependencyResolutionManagement {
+    versionCatalogs {
+        create("libs") {
+            from(files("../gradle/libs.versions.toml"))
+        }
+    }
+}

buildSrc/src/main/kotlin/sb-ot-demo.jacoco-rules.gradle.kts

@@ -0,0 +1,46 @@
+plugins {
+    id("java")
+    id("jacoco")
+}
+tasks {
+    jacocoTestCoverageVerification {
+        dependsOn(jacocoTestReport)
+        violationRules {
+            rule {
+                limit {
+                    counter = "CLASS"
+                    value = "MISSEDCOUNT"
+                    maximum = "0.0".toBigDecimal()
+                }
+            }
+            rule {
+                limit {
+                    counter = "METHOD"
+                    value = "MISSEDCOUNT"
+                    maximum = "2.0".toBigDecimal()
+                }
+            }
+            rule {
+                limit {
+                    counter = "LINE"
+                    value = "MISSEDCOUNT"
+                    maximum = "7.0".toBigDecimal()
+                }
+            }
+            rule {
+                limit {
+                    counter = "INSTRUCTION"
+                    value = "COVEREDRATIO"
+                    minimum = "0.93".toBigDecimal()
+                }
+            }
+            rule {
+                limit {
+                    counter = "BRANCH"
+                    value = "COVEREDRATIO"
+                    minimum = "0.66".toBigDecimal()
+                }
+            }
+        }
+    }
+}

buildSrc/src/main/kotlin/sb-ot-demo.java-compile.gradle.kts

@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2020-2025. Ivan Vakhrushev and others.
+ * https://github.com/mfvanek/spring-boot-open-telemetry-demo
+ *
+ * Licensed under the Apache License 2.0
+ */
+val javaVersion = JavaVersion.VERSION_17
+plugins {
+    id("java")
+    id("jacoco")
+    id("com.google.osdetector")
+    id("org.gradle.test-retry")
+}
+dependencies {
+    testImplementation("org.assertj:assertj-core")
+    testImplementation("org.junit.jupiter:junit-jupiter-api")
+    testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine")
+    testRuntimeOnly("org.junit.platform:junit-platform-launcher")
+    // https://github.com/netty/netty/issues/11020
+    if (osdetector.arch == "aarch_64") {
+        testImplementation("io.netty:netty-all:4.1.104.Final")
+    }
+}
+
+java {
+    sourceCompatibility = javaVersion
+    targetCompatibility = javaVersion
+    withJavadocJar()
+    withSourcesJar()
+}
+
+tasks {
+    withType<JavaCompile>().configureEach {
+        options.compilerArgs.add("-parameters")
+        options.compilerArgs.add("--should-stop=ifError=FLOW")
+    }
+
+    test {
+        useJUnitPlatform()
+
+        finalizedBy(jacocoTestReport, jacocoTestCoverageVerification)
+        maxParallelForks = 1
+
+        retry {
+            maxRetries.set(2)
+            maxFailures.set(5)
+            failOnPassedAfterRetry.set(false)
+        }
+    }
+
+    jacocoTestReport {
+        dependsOn(test)
+        reports {
+            xml.required.set(true)
+            html.required.set(true)
+        }
+    }
+
+    check {
+        dependsOn(jacocoTestCoverageVerification)
+    }
+}

buildSrc/src/main/kotlin/sb-ot-demo.java-conventions.gradle.kts

@@ -19,6 +19,8 @@ plugins {
     id("net.ltgt.errorprone")
     id("com.google.osdetector")
     id("org.gradle.test-retry")
+    id("sb-ot-demo.java-compile")
+    id("sb-ot-demo.jacoco-rules")
 }
 
 dependencies {
@@ -43,16 +45,6 @@ dependencies {
     spotbugsPlugins("com.mebigfatguy.sb-contrib:sb-contrib:7.6.9")
 }
 
-java {
-    toolchain {
-        languageVersion = JavaLanguageVersion.of(17)
-    }
-}
-
-jacoco {
-    toolVersion = "0.8.12"
-}
-
 checkstyle {
     toolVersion = "10.21.1"
     configFile = file("${rootDir}/config/checkstyle/checkstyle.xml")
@@ -84,77 +76,13 @@ tasks.withType<SpotBugsTask>().configureEach {
 
 tasks {
     withType<JavaCompile>().configureEach {
-        options.compilerArgs.add("-parameters")
-        options.compilerArgs.add("--should-stop=ifError=FLOW")
         options.errorprone {
             disableWarningsInGeneratedCode.set(true)
             disable("Slf4jLoggerShouldBeNonStatic")
         }
     }
 
     test {
-        useJUnitPlatform()
         dependsOn(checkstyleMain, checkstyleTest, pmdMain, pmdTest, spotbugsMain, spotbugsTest)
-        finalizedBy(jacocoTestReport, jacocoTestCoverageVerification)
-        maxParallelForks = 1
-
-        retry {
-            maxRetries.set(2)
-            maxFailures.set(5)
-            failOnPassedAfterRetry.set(false)
-        }
-    }
-
-    jacocoTestCoverageVerification {
-        dependsOn(jacocoTestReport)
-        violationRules {
-            rule {
-                limit {
-                    counter = "CLASS"
-                    value = "MISSEDCOUNT"
-                    maximum = "0.0".toBigDecimal()
-                }
-            }
-            rule {
-                limit {
-                    counter = "METHOD"
-                    value = "MISSEDCOUNT"
-                    maximum = "2.0".toBigDecimal()
-                }
-            }
-            rule {
-                limit {
-                    counter = "LINE"
-                    value = "MISSEDCOUNT"
-                    maximum = "7.0".toBigDecimal()
-                }
-            }
-            rule {
-                limit {
-                    counter = "INSTRUCTION"
-                    value = "COVEREDRATIO"
-                    minimum = "0.93".toBigDecimal()
-                }
-            }
-            rule {
-                limit {
-                    counter = "BRANCH"
-                    value = "COVEREDRATIO"
-                    minimum = "0.66".toBigDecimal()
-                }
-            }
-        }
-    }
-
-    jacocoTestReport {
-        dependsOn(test)
-        reports {
-            xml.required.set(true)
-            html.required.set(true)
-        }
-    }
-
-    check {
-        dependsOn(jacocoTestCoverageVerification)
     }
 }

buildSrc/src/main/kotlin/sb-ot-demo.kotlin-conventions.gradle.kts

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2020-2025. Ivan Vakhrushev and others.
+ * https://github.com/mfvanek/spring-boot-open-telemetry-demo
+ *
+ * Licensed under the Apache License 2.0
+ */
+
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+plugins {
+    id("java")
+    id("jacoco")
+    id("org.jetbrains.kotlin.jvm")
+    id("org.jetbrains.kotlin.plugin.spring")
+    id("io.gitlab.arturbosch.detekt")
+    id("sb-ot-demo.forbidden-apis")
+    id("sb-ot-demo.java-compile")
+}
+
+private val versionCatalog = extensions.getByType<VersionCatalogsExtension>().named("libs")
+
+dependencies {
+    implementation("org.jetbrains.kotlin:kotlin-reflect")
+    versionCatalog.findLibrary("detekt-formatting").ifPresent {
+        detektPlugins(it)
+    }
+    versionCatalog.findLibrary("detekt-libraries").ifPresent {
+        detektPlugins(it)
+    }
+}
+
+tasks.withType<KotlinCompile> {
+    compilerOptions {
+        freeCompilerArgs.add("-Xjsr305=strict")
+        jvmTarget = JvmTarget.JVM_17
+    }
+}
+
+detekt {
+    toolVersion = versionCatalog.findVersion("detekt").get().requiredVersion
+    config.setFrom(file("${rootDir}/config/detekt/detekt.yml"))
+    buildUponDefaultConfig = true
+}
+
+tasks {
+    withType<JavaCompile>().configureEach {
+        options.compilerArgs.add("-parameters")
+        options.compilerArgs.add("--should-stop=ifError=FLOW")
+    }
+
+    test {
+        testLogging.showStandardStreams = false // set to true for debug purposes
+    }
+}

config/detekt/detekt.yml

@@ -0,0 +1,7 @@
+performance:
+    SpreadOperator:
+        active: false
+
+style:
+    MaxLineLength:
+        maxLineLength: 200

gradle/libs.versions.toml

@@ -0,0 +1,16 @@
+[versions]
+detekt = "1.23.8"
+spring-boot-v3 = "3.4.4"
+
+[libraries]
+detekt = { group = "io.gitlab.arturbosch.detekt", name = "detekt-gradle-plugin", version.ref = "detekt" }
+detekt-formatting = { group = "io.gitlab.arturbosch.detekt", name = "detekt-formatting", version.ref = "detekt" }
+detekt-libraries = { group = "io.gitlab.arturbosch.detekt", name = "detekt-rules-libraries", version.ref = "detekt" }
+spring-boot-v3-dependencies = { group = "org.springframework.boot", name = "spring-boot-dependencies", version.ref = "spring-boot-v3" }
+springdoc-openapi = "org.springdoc:springdoc-openapi:2.8.6"
+spring-cloud = "org.springframework.cloud:spring-cloud-dependencies:2024.0.1"
+datasource-micrometer = "net.ttddyy.observation:datasource-micrometer-spring-boot:1.1.0"
+logstash = "net.logstash.logback:logstash-logback-encoder:8.0"
+
+[plugins]
+spring-boot-v3 = { id = "org.springframework.boot", version.ref = "spring-boot-v3" }

settings.gradle.kts

@@ -1,17 +1,7 @@
 rootProject.name = "spring-boot-open-telemetry-demo"
+
 include("spring-boot-3-demo-app")
 include("common-internal-bom")
 include("spring-boot-2-demo-app")
 include("db-migrations")
-
-dependencyResolutionManagement {
-    versionCatalogs {
-        create("libs") {
-            val springBoot3Version = version("spring-boot-v3", "3.4.4")
-            plugin("spring-boot-v3", "org.springframework.boot")
-                .versionRef(springBoot3Version)
-            library("spring-boot-v3-dependencies", "org.springframework.boot", "spring-boot-dependencies")
-                .versionRef(springBoot3Version)
-        }
-    }
-}
+include("spring-boot-3-demo-app-kotlin")