Spring Boot Kotlin Scaffold

Build Spring Boot services in Kotlin with coroutines and WebFlux.

When to Use

• Building Kotlin microservices with Spring Boot
• Using coroutines for async endpoint handling
• Setting up Gradle with Kotlin DSL
• Creating REST APIs with Spring WebFlux

build.gradle.kts

plugins {
    kotlin("jvm") version "2.0.0"
    kotlin("plugin.spring") version "2.0.0"
    id("org.springframework.boot") version "3.3.0"
    id("io.spring.dependency-management") version "1.1.5"
}

dependencies {
    implementation("org.springframework.boot:spring-boot-starter-webflux")
    implementation("com.fasterxml.jackson.module:jackson-module-kotlin")
    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-reactor")
    testImplementation("org.springframework.boot:spring-boot-starter-test")
}

Controller with Coroutines

@RestController
@RequestMapping("/api")
class ChatController(private val chatService: ChatService) {

    @PostMapping("/chat")
    suspend fun chat(@RequestBody request: ChatRequest): ChatResponse {
        return chatService.chat(request)
    }

    @GetMapping("/health")
    suspend fun health(): Map<String, String> {
        return mapOf("status" to "healthy")
    }
}

data class ChatRequest(val message: String, val model: String = "gpt-4o-mini")
data class ChatResponse(val reply: String, val tokens: Int)

Service

@Service
class ChatService(private val openAIClient: OpenAIClient) {

    suspend fun chat(request: ChatRequest): ChatResponse {
        val response = openAIClient.complete(request.message, request.model)
        return ChatResponse(
            reply = response.content,
            tokens = response.totalTokens
        )
    }
}

Configuration

@Configuration
class OpenAIConfig {
    @Bean
    fun openAIClient(
        @Value("\${azure.openai.endpoint}") endpoint: String
    ): OpenAIClient {
        return OpenAIClient(endpoint, DefaultAzureCredential())
    }
}

Troubleshooting