Genkit Java Samples

January 5, 2026 · View on GitHub

This directory contains sample applications demonstrating various features of Genkit Java SDK.

Prerequisites

All samples require:

Java 21+
Maven 3.6+
API Key for the model provider (OpenAI or Google GenAI)

Quick Start

Each sample can be run with:

# 1. Set your API key (OpenAI samples)
export OPENAI_API_KEY=your-api-key-here

# Or for Google GenAI samples
export GOOGLE_GENAI_API_KEY=your-api-key-here

# 2. Navigate to the sample directory
cd java/samples/<sample-name>

# 3. Run the sample
./run.sh
# Or: mvn compile exec:java

Running with Genkit Dev UI

For the best development experience, use the Genkit CLI to run samples with the Dev UI:

# Install Genkit CLI (if not already installed)
npm install -g genkit

# Run sample with Dev UI
cd java/samples/<sample-name>
genkit start -- ./run.sh
# Or: genkit start -- mvn exec:java

The Dev UI will be available at http://localhost:4000 and allows you to:

View all registered actions (flows, models, tools, prompts)
Run flows with test inputs
Inspect traces and execution logs
Manage datasets and run evaluations

Available Samples

Sample	Description	API Key Required
openai	Basic OpenAI integration with flows and tools	`OPENAI_API_KEY`
google-genai	Google Gemini integration with image generation	`GOOGLE_GENAI_API_KEY`
anthropic	Anthropic Claude integration with streaming	`ANTHROPIC_API_KEY`
ollama	Local Ollama models (Gemma, Llama, Mistral)	None (local)
xai	XAI Grok models with tool calling and streaming	`XAI_API_KEY`
deepseek	DeepSeek models with reasoning and code generation	`DEEPSEEK_API_KEY`
cohere	Cohere Command models with RAG and tool usage	`COHERE_API_KEY`
mistral	Mistral AI models including Codestral and Ministral	`MISTRAL_API_KEY`
groq	Ultra-fast Groq inference with Llama and GPT-OSS	`GROQ_API_KEY`
dotprompt	DotPrompt files with complex inputs/outputs, variants, and partials	`OPENAI_API_KEY`
rag	RAG application with local vector store	`OPENAI_API_KEY`
chat-session	Multi-turn chat with session persistence	`OPENAI_API_KEY`
evaluations	Custom evaluators and evaluation workflows	`OPENAI_API_KEY`
evaluators-plugin	Pre-built RAGAS-style evaluators plugin demo	`OPENAI_API_KEY`
complex-io	Complex nested types, arrays, maps in flow inputs/outputs	`OPENAI_API_KEY`
middleware	Middleware patterns for logging, caching, rate limiting	`OPENAI_API_KEY`
multi-agent	Multi-agent orchestration patterns	`OPENAI_API_KEY`
interrupts	Flow interrupts and human-in-the-loop patterns	`OPENAI_API_KEY`
mcp	Model Context Protocol (MCP) integration	`OPENAI_API_KEY`
firebase	Firebase Firestore RAG and Cloud Functions	`GEMINI_API_KEY` + `GCLOUD_PROJECT`
spring	Spring Boot HTTP server integration	`GOOGLE_GENAI_API_KEY` (optional)
weaviate	Weaviate vector database RAG sample	`OPENAI_API_KEY`
postgresql	PostgreSQL pgvector RAG sample	`OPENAI_API_KEY`
pinecone	Pinecone vector database RAG sample	`OPENAI_API_KEY` + `PINECONE_API_KEY`

Sample Details

OpenAI Sample

Basic integration with OpenAI models demonstrating:

Text generation with GPT-4o
Tool usage
Streaming responses
Flow definitions

cd java/samples/openai
export OPENAI_API_KEY=your-key
./run.sh

Google GenAI Sample

Integration with Google Gemini models demonstrating:

Text generation with Gemini
Image generation with Imagen
Multi-modal inputs

cd java/samples/google-genai
export GOOGLE_GENAI_API_KEY=your-key
./run.sh

DotPrompt Sample

Template-based prompts with Handlebars demonstrating:

Loading .prompt files
Complex input/output schemas
Prompt variants (e.g., recipe.robot.prompt)
Partials for reusable templates

cd java/samples/dotprompt
export OPENAI_API_KEY=your-key
./run.sh

RAG Sample

Retrieval-Augmented Generation demonstrating:

Local vector store for development
Document indexing and retrieval
Semantic search with embeddings
Context-aware generation

cd java/samples/rag
export OPENAI_API_KEY=your-key
./run.sh

Chat Session Sample

Multi-turn conversations demonstrating:

Conversation history management
Session state persistence
Tool integration within sessions
Multiple chat personas

cd java/samples/chat-session
export OPENAI_API_KEY=your-key
./run.sh

Evaluations Sample

AI output evaluation demonstrating:

Custom evaluator definitions
Dataset management
Evaluation workflows
Quality metrics

cd java/samples/evaluations
export OPENAI_API_KEY=your-key
./run.sh

Evaluators Plugin Sample

Pre-built RAGAS-style evaluators demonstrating:

LLM-based evaluators (Faithfulness, Answer Relevancy, Answer Accuracy, Maliciousness)
Programmatic evaluators (Regex, Deep Equal, JSONata)
Configurable judge models per metric
Integration with Genkit Dev UI evaluation workflow

cd java/samples/evaluators-plugin
export OPENAI_API_KEY=your-key
./run.sh

Complex I/O Sample

Complex type handling demonstrating:

Deeply nested object types
Arrays and collections
Optional fields and maps
Domain objects (e-commerce, analytics)

cd java/samples/complex-io
export OPENAI_API_KEY=your-key
./run.sh

Middleware Sample

Cross-cutting concerns demonstrating:

Logging middleware
Caching middleware
Rate limiting
Request/response transformation
Error handling

cd java/samples/middleware
export OPENAI_API_KEY=your-key
./run.sh

Multi-Agent Sample

Multi-agent orchestration demonstrating:

Agent coordination patterns
Task delegation
Inter-agent communication

cd java/samples/multi-agent
export OPENAI_API_KEY=your-key
./run.sh

Interrupts Sample

Flow control demonstrating:

Human-in-the-loop patterns
Flow interrupts and resumption
External input handling

cd java/samples/interrupts
export OPENAI_API_KEY=your-key
./run.sh

MCP Sample

Model Context Protocol integration demonstrating:

MCP server connections
Tool discovery and usage
Resource management
File operations

cd java/samples/mcp
export OPENAI_API_KEY=your-key
./run.sh

Firebase Sample

Firebase integration demonstrating:

Firestore vector search for RAG
Document indexing with embeddings
Exposing flows as Cloud Functions
Firebase telemetry (Cloud Trace, Monitoring, Logging)

cd java/samples/firebase
export GEMINI_API_KEY=your-key
export GCLOUD_PROJECT=your-project-id
./run.sh

Spring Sample

Spring Boot HTTP server integration demonstrating:

REST endpoint generation for flows
Health check and flow listing endpoints
Spring Boot ecosystem integration
Configurable port, host, and base path

cd java/samples/spring
# Optional: export GOOGLE_GENAI_API_KEY=your-key
./run.sh

Anthropic Sample

Anthropic Claude integration demonstrating:

Text generation with Claude models
Streaming responses
Tool usage with Claude

cd java/samples/anthropic
export ANTHROPIC_API_KEY=your-key
./run.sh

XAI Sample

XAI Grok models demonstrating:

Latest Grok 4 and Grok 4.1 Fast models
Optimized tool calling with 2M context
Efficient Grok 3 and 3 Mini models
Streaming responses

cd java/samples/xai
export XAI_API_KEY=your-key
./run.sh

DeepSeek Sample

DeepSeek models demonstrating:

DeepSeek-V3.2 for chat and code generation
Advanced reasoning with DeepSeek Reasoner
Mathematical problem solving with tools
Code review and generation

cd java/samples/deepseek
export DEEPSEEK_API_KEY=your-key
./run.sh

Cohere Sample

Cohere Command models demonstrating:

Command A flagship model with 256K context
Command R7B for fast, efficient processing
RAG workflows and tool usage
Streaming responses

cd java/samples/cohere
export COHERE_API_KEY=your-key
./run.sh

Mistral Sample

Mistral AI models demonstrating:

Mistral Large 3 multimodal flagship
Ministral 3 compact models (3B/8B/14B)
Codestral for code generation
Translation and multilingual support

cd java/samples/mistral
export MISTRAL_API_KEY=your-key
./run.sh

Groq Sample

Groq ultra-fast inference demonstrating:

Llama 3.3 70B and 3.1 8B models
OpenAI GPT-OSS models (120B/20B)
Speed benchmarking (560+ tokens/sec)
Real-time streaming responses

cd java/samples/groq
export GROQ_API_KEY=your-key
./run.sh

Ollama Sample

Local Ollama models demonstrating:

Running models locally without API keys
Support for Gemma, Llama, Mistral, and other models
Local development and testing

cd java/samples/ollama
# Requires Ollama running locally: ollama serve
./run.sh

Weaviate Sample

Weaviate vector database RAG demonstrating:

Vector similarity search
Document indexing with embeddings
Retrieval-augmented generation

cd java/samples/weaviate
export OPENAI_API_KEY=your-key
# Requires Weaviate running (Docker or cloud)
./run.sh

PostgreSQL Sample

PostgreSQL with pgvector RAG demonstrating:

Vector similarity search with pgvector
Document storage and retrieval
SQL-based vector operations

cd java/samples/postgresql
export OPENAI_API_KEY=your-key
# Requires PostgreSQL with pgvector extension
./run.sh

Pinecone Sample

Pinecone vector database RAG demonstrating:

Managed vector database integration
High-performance similarity search
Cloud-native vector storage

cd java/samples/pinecone
export OPENAI_API_KEY=your-key
export PINECONE_API_KEY=your-key
./run.sh

Building All Samples

From the Java root directory:

cd java
mvn clean install

Common Issues

API Key Not Set

Error: OPENAI_API_KEY environment variable is not set

Solution: Set the required API key for the sample you're running.

Port Already in Use

Error: Address already in use (Bind failed)

Solution: The default port (8080 or 3100) is in use. Either stop the other process or configure a different port.

Maven Dependencies Not Found

Error: Could not find artifact com.google.genkit:genkit

Solution: Build the parent project first:

cd java
mvn clean install -DskipTests

Additional Resources

Genkit Java README - Main documentation
Genkit Documentation - Official docs
Genkit GitHub - Source code