Spring Boot Integration

Deploy Koog AI agents in a Spring Boot application with REST API endpoints, MCP server integration, and S3 persistence.

Overview

This example demonstrates a production-ready Spring Boot application that:

Exposes agents via REST API
Integrates with MCP servers (GitHub example)
Supports S3 persistence for agent state
Configures agents via YAML
Uses Google’s Gemini models

Features

REST API

HTTP endpoints for chat interactions with full async support

MCP Integration

Connect to Model Context Protocol servers (GitHub, Google Maps, etc.)

S3 Persistence

Optional agent state persistence to AWS S3

YAML Configuration

Declarative agent and tool configuration

Quick Start

Prerequisites

Ensure you have:

Java 17 or higher
Docker (for MCP servers)
Gradle 8.14
Google API key
GitHub personal access token
Optional: AWS credentials for S3 persistence

Set Environment Variables

export GOOGLE_API_KEY="your_google_key"
export GITHUB_PERSONAL_ACCESS_TOKEN="your_github_token"

# Optional: for S3 persistence
export AWS_ACCESS_KEY_ID="your_aws_key"
export AWS_SECRET_ACCESS_KEY="your_aws_secret"

Start Docker

Docker is required for MCP server containers:

docker ps  # Verify Docker is running

Run the Application

cd examples/spring-boot-kotlin
./gradlew bootRun

Application starts on http://localhost:8080

Test the API

curl -X POST http://localhost:8080/chat \
  -H "Content-Type: application/json" \
  -d '{"prompt": "List the last 3 commits in your_username/your_repo"}'

Project Structure

spring-boot-kotlin/
├── src/main/kotlin/com/example/agent/
│   ├── SpringBootKotlinApplication.kt    # Main application
│   ├── config/
│   │   ├── AgentConfiguration.kt         # YAML config data classes
│   │   └── AppConfiguration.kt           # Spring configuration
│   ├── controller/
│   │   └── ChatController.kt             # REST endpoint
│   ├── model/
│   │   └── Models.kt                     # Request/response models
│   └── service/
│       ├── AgentService.kt               # Agent creation logic
│       ├── ToolRegistryProvider.kt       # Tool setup
│       └── S3StorageProvider.kt          # S3 persistence
├── src/main/resources/
│   └── application.yml                   # Configuration
└── build.gradle.kts

Implementation

Main Application

SpringBootKotlinApplication.kt

package com.example.agent

import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication

@SpringBootApplication
class SpringBootKotlinApplication

fun main(args: Array<String>) {
    runApplication<SpringBootKotlinApplication>(*args)
}

REST Controller

ChatController.kt

package com.example.agent.controller

import com.example.agent.service.AgentService
import io.github.oshai.kotlinlogging.KotlinLogging
import org.springframework.http.HttpStatus
import org.springframework.web.bind.annotation.PostMapping
import org.springframework.web.bind.annotation.RequestBody
import org.springframework.web.bind.annotation.RestController
import org.springframework.web.server.ResponseStatusException

private val logger = KotlinLogging.logger {}

@RestController
class ChatController(val agentService: AgentService) {

    @PostMapping(value = ["/chat"])
    suspend fun chat(@RequestBody request: ChatRequest): ChatResponse {
        try {
            val result = agentService.createAndRunAgent(request.prompt)
            return ChatResponse(result)
        } catch (e: Exception) {
            logger.error(e) { "Failed to run an agent" }
            throw ResponseStatusException(
                HttpStatus.INTERNAL_SERVER_ERROR,
                "Failed to run an agent"
            )
        }
    }
}

data class ChatRequest(val prompt: String)
data class ChatResponse(val response: String)

Agent Service

Creates and executes agents based on YAML configuration:

AgentService.kt

package com.example.agent.service

import ai.koog.agents.core.agent.AIAgent
import ai.koog.agents.core.agent.config.AIAgentConfig
import ai.koog.agents.core.agent.singleRunStrategy
import ai.koog.agents.core.tools.ToolRegistry
import ai.koog.agents.features.eventHandler.feature.handleEvents
import ai.koog.agents.features.persistence.feature.S3Persistence
import ai.koog.prompt.dsl.prompt
import ai.koog.prompt.executor.clients.google.GoogleLLMClient
import ai.koog.prompt.executor.clients.google.GoogleModels
import com.example.agent.config.AgentConfiguration
import io.github.oshai.kotlinlogging.KotlinLogging
import org.springframework.stereotype.Service

private val logger = KotlinLogging.logger {}

@Service
class AgentService(
    private val agentConfiguration: AgentConfiguration,
    private val toolRegistryProvider: ToolRegistryProvider,
    private val s3StorageProvider: S3StorageProvider?
) {
    private val googleApiKey = System.getenv("GOOGLE_API_KEY")
        ?: error("GOOGLE_API_KEY environment variable is not set")

    suspend fun createAndRunAgent(userPrompt: String): String {
        val executor = GoogleLLMClient(googleApiKey)
        
        // Build tool registry from configuration
        val toolRegistry = toolRegistryProvider.createToolRegistry(
            agentConfiguration.tools
        )

        // Create agent config
        val agentConfig = AIAgentConfig(
            prompt = prompt("chat-agent") {
                agentConfiguration.systemPrompt?.let { system(it) }
            },
            model = GoogleModels.fromId(agentConfiguration.model.id),
            maxAgentIterations = 100
        )

        // Create the agent
        val agent = AIAgent(
            promptExecutor = executor,
            strategy = singleRunStrategy(),
            agentConfig = agentConfig,
            toolRegistry = toolRegistry
        ) {
            // Optional S3 persistence
            if (s3StorageProvider != null && 
                agentConfiguration.s3Persistence?.enabled == true) {
                install(S3Persistence) {
                    storageProvider = s3StorageProvider
                }
            }

            handleEvents {
                onToolCallStarting { ctx ->
                    logger.info { "Tool called: ${ctx.toolName}" }
                }
                onAgentExecutionFailed { ctx ->
                    logger.error(ctx.throwable) { "Agent execution failed" }
                }
            }
        }

        // Run the agent
        return agent.run(userPrompt)
    }
}

Tool Registry Provider

Dynamically creates tool registries from YAML configuration:

ToolRegistryProvider.kt

package com.example.agent.service

import ai.koog.agents.core.tools.ToolRegistry
import ai.koog.agents.mcp.McpToolRegistryProvider
import com.example.agent.config.AgentConfiguration.ToolDefinition
import com.example.agent.config.AgentConfiguration.ToolType
import io.modelcontextprotocol.kotlin.sdk.client.StdioClientTransport
import kotlinx.coroutines.Dispatchers
import org.springframework.stereotype.Component

@Component
class ToolRegistryProvider {
    private val mcpTransports = mutableListOf<StdioClientTransport>()

    suspend fun createToolRegistry(
        toolDefinitions: List<ToolDefinition>
    ): ToolRegistry {
        var registry = ToolRegistry { }

        for (toolDef in toolDefinitions) {
            when (toolDef.type) {
                ToolType.MCP -> {
                    val mcpRegistry = createMcpToolRegistry(toolDef)
                    registry += mcpRegistry
                }
                ToolType.SIMPLE -> {
                    // Add custom simple tools here
                }
            }
        }

        return registry
    }

    private suspend fun createMcpToolRegistry(
        toolDef: ToolDefinition
    ): ToolRegistry {
        val dockerImage = toolDef.options.dockerImage
            ?: error("Docker image required for MCP tool ${toolDef.id}")

        // Build docker command
        val command = buildList {
            add("docker")
            add("run")
            add("-i")
            
            // Add environment variables
            toolDef.options.dockerOptions?.forEach { (key, value) ->
                add("-e")
                add("$key=$value")
            }
            
            add(dockerImage)
        }

        // Start MCP server process
        val process = ProcessBuilder(command)
            .redirectInput(ProcessBuilder.Redirect.PIPE)
            .redirectOutput(ProcessBuilder.Redirect.PIPE)
            .start()

        kotlinx.coroutines.delay(1000) // Wait for server to start

        // Create transport
        val transport = McpToolRegistryProvider.defaultStdioTransport(process)
        mcpTransports.add(transport)

        // Return tool registry
        return McpToolRegistryProvider.fromTransport(transport)
    }

    fun cleanup() {
        mcpTransports.forEach { it.close() }
    }
}

S3 Storage Provider

Implements agent state persistence to AWS S3:

S3StorageProvider.kt

package com.example.agent.service

import ai.koog.agents.features.persistence.StorageProvider
import com.example.agent.config.AgentConfiguration
import org.springframework.stereotype.Component
import software.amazon.awssdk.services.s3.S3Client
import software.amazon.awssdk.services.s3.model.*

@Component
class S3StorageProvider(
    private val agentConfiguration: AgentConfiguration
) : StorageProvider {
    private val s3Config = agentConfiguration.s3Persistence
    private val s3Client: S3Client? = if (s3Config?.enabled == true) {
        S3Client.builder()
            .region(Region.of(s3Config.region))
            .build()
    } else null

    override suspend fun save(key: String, data: ByteArray) {
        val client = s3Client ?: return
        val fullKey = "${s3Config?.path}/$key"
        
        client.putObject(
            PutObjectRequest.builder()
                .bucket(s3Config?.bucket)
                .key(fullKey)
                .build(),
            RequestBody.fromBytes(data)
        )
    }

    override suspend fun load(key: String): ByteArray? {
        val client = s3Client ?: return null
        val fullKey = "${s3Config?.path}/$key"
        
        return try {
            client.getObject(
                GetObjectRequest.builder()
                    .bucket(s3Config?.bucket)
                    .key(fullKey)
                    .build()
            ).readAllBytes()
        } catch (e: NoSuchKeyException) {
            null
        }
    }

    override suspend fun delete(key: String) {
        val client = s3Client ?: return
        val fullKey = "${s3Config?.path}/$key"
        
        client.deleteObject(
            DeleteObjectRequest.builder()
                .bucket(s3Config?.bucket)
                .key(fullKey)
                .build()
        )
    }
}

Configuration

application.yml

The agent is fully configured via YAML:

application.yml

agent:
  version: "1.0.0"
  name: "GitHub Assistant"
  description: "AI agent that helps with GitHub operations"
  
  model:
    id: "gemini-2.5-flash"
    options:
      temperature: 0.3
  
  system_prompt: |
    You are a helpful GitHub assistant.
    You can help users with repository operations, commit history, and more.
    Use the available tools to access GitHub data.
  
  tools:
    - type: MCP
      id: "github"
      options:
        docker_image: "mcp/github"
        docker_options:
          GITHUB_PERSONAL_ACCESS_TOKEN: "${GITHUB_PERSONAL_ACCESS_TOKEN}"
  
  # Optional S3 persistence
  s3_persistence:
    enabled: false  # Set to true to enable
    region: "us-east-1"
    bucket: "my-agent-state-bucket"
    path: "agents/github-assistant"

Configuration Data Classes

AgentConfiguration.kt

package com.example.agent.config

import com.fasterxml.jackson.annotation.JsonProperty
import org.springframework.boot.context.properties.ConfigurationProperties

@ConfigurationProperties(prefix = "agent")
data class AgentConfiguration(
    val version: String,
    val name: String,
    val description: String,
    val model: Model,
    @field:JsonProperty("system_prompt")
    val systemPrompt: String? = null,
    val tools: List<ToolDefinition> = emptyList(),
    val s3Persistence: S3Persistence? = null,
) {
    data class Model(
        val id: String,
        val options: ModelOptions? = null,
    )

    data class ModelOptions(
        val temperature: Double? = null,
    )

    data class ToolDefinition(
        val type: ToolType,
        val id: String,
        val options: ToolOptions = ToolOptions()
    )

    data class ToolOptions(
        @field:JsonProperty("docker_image")
        val dockerImage: String? = null,
        @field:JsonProperty("docker_options")
        val dockerOptions: Map<String, String>? = null,
    )

    data class S3Persistence(
        @field:JsonProperty("enabled")
        val enabled: Boolean,
        @field:JsonProperty("region")
        val region: String,
        @field:JsonProperty("bucket")
        val bucket: String,
        @field:JsonProperty("path")
        val path: String,
    )

    enum class ToolType {
        SIMPLE, MCP
    }
}

API Usage

Chat Endpoint

Endpoint: POST /chat Request:

{
  "prompt": "List the last three commits in the repository username/repo-name and summarize them"
}

Response:

{
  "response": "Here's a summary of the last three commits in the username/repo-name repository:\n\n1. **Create script.sh**: This commit created a shell script file named `script.sh`.\n2. **Initial commit**: This is the initial commit, likely setting up the basic structure of the repository.\n\n"
}

Using cURL

curl -v -X POST http://localhost:8080/chat \
  -H "Content-Type: application/json" \
  -d '{
    "prompt": "List the last three commits in the GitHub repository your_username/your_repo and summarize them."
  }' | jq

Using HTTPie

http POST http://localhost:8080/chat \
  prompt="What are the open issues in username/repo?"

Supported Models

The example uses Google’s Gemini models. Supported models:

gemini-2.0-flash
gemini-2.0-flash-001
gemini-2.0-flash-lite
gemini-2.0-flash-lite-001
gemini-2.5-pro
gemini-2.5-flash
gemini-2.5-flash-lite

Change the model in application.yml:

agent:
  model:
    id: "gemini-2.5-pro"  # Use the most capable model
    options:
      temperature: 0.7

MCP Server Integration

Available MCP Servers

The application can integrate with any MCP server. Examples:

GitHub
Google Maps
Slack

tools:
  - type: MCP
    id: "github"
    options:
      docker_image: "mcp/github"
      docker_options:
        GITHUB_PERSONAL_ACCESS_TOKEN: "${GITHUB_PERSONAL_ACCESS_TOKEN}"

Capabilities:

List repositories
Get commit history
Search issues and PRs
Create/update issues

tools:
  - type: MCP
    id: "google-maps"
    options:
      docker_image: "mcp/google-maps"
      docker_options:
        GOOGLE_MAPS_API_KEY: "${GOOGLE_MAPS_API_KEY}"

Capabilities:

Search places
Get directions
Calculate distances
Place details and reviews

tools:
  - type: MCP
    id: "slack"
    options:
      docker_image: "mcp/slack"
      docker_options:
        SLACK_BOT_TOKEN: "${SLACK_BOT_TOKEN}"

Capabilities:

Send messages
List channels
Read message history
Manage threads

Multiple MCP Servers

Combine multiple MCP servers:

tools:
  - type: MCP
    id: "github"
    options:
      docker_image: "mcp/github"
      docker_options:
        GITHUB_PERSONAL_ACCESS_TOKEN: "${GITHUB_PERSONAL_ACCESS_TOKEN}"
  
  - type: MCP
    id: "jira"
    options:
      docker_image: "mcp/jira"
      docker_options:
        JIRA_URL: "${JIRA_URL}"
        JIRA_API_TOKEN: "${JIRA_API_TOKEN}"

S3 Persistence

Enable state persistence to AWS S3 for long-running conversations:

Configuration

agent:
  s3_persistence:
    enabled: true
    region: "us-east-1"
    bucket: "my-agent-state-bucket"
    path: "agents/production"

Environment Variables

export AWS_ACCESS_KEY_ID="your_aws_access_key"
export AWS_SECRET_ACCESS_KEY="your_aws_secret_key"

What Gets Persisted

Conversation history
Agent state and storage
Tool execution results
Session context

Production Deployment

Docker Deployment

Create a Dockerfile:

Dockerfile

FROM eclipse-temurin:17-jdk-alpine
WORKDIR /app

COPY build/libs/*.jar app.jar

EXPOSE 8080
ENTRYPOINT ["java", "-jar", "app.jar"]

Build and run:

./gradlew bootJar
docker build -t koog-agent .
docker run -p 8080:8080 \
  -e GOOGLE_API_KEY=your_key \
  -e GITHUB_PERSONAL_ACCESS_TOKEN=your_token \
  koog-agent

Kubernetes Deployment

deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: koog-agent
spec:
  replicas: 3
  selector:
    matchLabels:
      app: koog-agent
  template:
    metadata:
      labels:
        app: koog-agent
    spec:
      containers:
      - name: koog-agent
        image: koog-agent:latest
        ports:
        - containerPort: 8080
        env:
        - name: GOOGLE_API_KEY
          valueFrom:
            secretKeyRef:
              name: api-keys
              key: google-api-key
        - name: GITHUB_PERSONAL_ACCESS_TOKEN
          valueFrom:
            secretKeyRef:
              name: api-keys
              key: github-token
---
apiVersion: v1
kind: Service
metadata:
  name: koog-agent
spec:
  selector:
    app: koog-agent
  ports:
  - port: 80
    targetPort: 8080
  type: LoadBalancer

Customization

Change System Prompt

Modify agent behavior in application.yml:

agent:
  system_prompt: |
    You are a senior software engineer specializing in code review.
    
    Your responsibilities:
    - Review code for bugs and security issues
    - Suggest performance improvements
    - Ensure code follows best practices
    - Provide constructive feedback
    
    Always explain your reasoning clearly.

Add Custom Tools

Implement custom tools:

CustomTools.kt

class DatabaseTools : ToolSet {
    @Tool
    @LLMDescription("Execute SQL query")
    suspend fun executeQuery(sql: String): QueryResult {
        // Implementation
    }
}

// Register in ToolRegistryProvider
when (toolDef.type) {
    ToolType.SIMPLE -> {
        when (toolDef.id) {
            "database" -> registry += ToolRegistry {
                tools(DatabaseTools().asTools())
            }
        }
    }
}

Add to application.yml:

tools:
  - type: SIMPLE
    id: "database"

Switch to Different LLM Provider

Modify AgentService.kt to use different providers:

// Use OpenAI instead of Google
val executor = OpenAILLMClient(System.getenv("OPENAI_API_KEY"))
val model = OpenAIModels.Chat.GPT4o

// Or Anthropic
val executor = AnthropicLLMClient(System.getenv("ANTHROPIC_API_KEY"))
val model = AnthropicModels.Claude_3_5_Sonnet

Troubleshooting

Docker Connection Issues

Symptoms: MCP servers fail to startSolutions:

Verify Docker is running: docker ps
Check Docker image exists: docker images | grep mcp
Increase startup delay in ToolRegistryProvider
Check Docker logs: docker logs <container_id>

API Key Errors

Symptoms: 401 Unauthorized errorsSolutions:

Verify environment variables are set
Check API key permissions (e.g., GitHub token scopes)
Ensure keys are not expired
Test keys independently before using with agent

S3 Permission Errors

Symptoms: Failed to save agent stateSolutions:

Verify AWS credentials are correct
Check S3 bucket exists and is accessible
Ensure IAM role has PutObject/GetObject permissions
Verify bucket region matches configuration

High Memory Usage

Symptoms: Application crashes or slows downSolutions:

Enable S3 persistence to offload state
Reduce maxAgentIterations in config
Implement history compression
Increase JVM heap size: -Xmx2g

Source Code

View on GitHub

Explore the complete Spring Boot integration example

Next Steps

MCP Integration

Learn about Model Context Protocol

Persistence

Deep dive into agent state management

Code Examples

​Overview

​Features

REST API

MCP Integration

S3 Persistence

YAML Configuration

​Quick Start

​Project Structure

​Implementation

​Main Application

​REST Controller

​Agent Service

​Tool Registry Provider

​S3 Storage Provider

​Configuration

​application.yml

​Configuration Data Classes

​API Usage

​Chat Endpoint

​Using cURL

​Using HTTPie

​Supported Models

​MCP Server Integration

​Available MCP Servers

​Multiple MCP Servers

​S3 Persistence

​Configuration

​Environment Variables

​What Gets Persisted

​Production Deployment

​Docker Deployment

​Kubernetes Deployment

​Customization

​Change System Prompt

​Add Custom Tools

​Switch to Different LLM Provider

​Troubleshooting

​Source Code

View on GitHub

​Next Steps

MCP Integration

Persistence

Build docs developers (and LLMs) love

Overview

Features

Quick Start

Project Structure

Implementation

Main Application

REST Controller

Agent Service

Tool Registry Provider

S3 Storage Provider

Configuration

application.yml

Configuration Data Classes

API Usage

Chat Endpoint

Using cURL

Using HTTPie

Supported Models

MCP Server Integration

Available MCP Servers

Multiple MCP Servers

S3 Persistence

Configuration

Environment Variables

What Gets Persisted

Production Deployment

Docker Deployment

Kubernetes Deployment

Customization

Change System Prompt

Add Custom Tools

Switch to Different LLM Provider

Troubleshooting

Source Code

Next Steps