/developing-genkit-go

name: developing-genkit-go
description: Develop AI-powered applications using Genkit in Go. Use when the user asks to build AI features, agents, flows, or tools in Go using Genkit, or when working with Genkit Go code involving generation, prompts, streaming, tool calling, or model providers.
metadata:
  category: AiAndMachineLearning

Genkit Go

Genkit Go is an AI SDK for Go that provides generation, structured output, streaming, tool calling, prompts, and flows with a unified interface across model providers.

Hello World

package main

import (
	"context"
	"fmt"
	"log"
	"net/http"

	"github.com/genkit-ai/genkit/go/ai"
	"github.com/genkit-ai/genkit/go/genkit"
	"github.com/genkit-ai/genkit/go/plugins/googlegenai"
	"github.com/genkit-ai/genkit/go/plugins/server"
)

func main() {
	ctx := context.Background()
	g := genkit.Init(ctx, genkit.WithPlugins(&googlegenai.GoogleAI{}))

	genkit.DefineFlow(g, "jokeFlow", func(ctx context.Context, topic string) (string, error) {
		return genkit.GenerateText(ctx, g,
			ai.WithModelName("googleai/gemini-flash-latest"),
			ai.WithPrompt("Tell me a joke about %s", topic),
		)
	})

	mux := http.NewServeMux()
	for _, f := range genkit.ListFlows(g) {
		mux.HandleFunc("POST /"+f.Name(), genkit.Handler(f))
	}
	log.Fatal(server.Start(ctx, "127.0.0.1:8080", mux))
}

Core Features

Load the appropriate reference based on what you need:

| Feature | Reference | When to load | | --- | --- | --- | | Initialization | [references/getting-started.md](references/getting-started.md) | Setting up `genkit.Init`, plugins, the `*Genkit` instance pattern | | Generation | [references/generation.md](references/generation.md) | `Generate`, `GenerateText`, `GenerateData`, streaming, output formats | | Prompts | [references/prompts.md](references/prompts.md) | `DefinePrompt`, `DefineDataPrompt`, `.prompt` files, schemas | | Tools | [references/tools.md](references/tools.md) | `DefineTool`, tool interrupts, `RestartWith`/`RespondWith` | | Middleware | [references/middleware.md](references/middleware.md) | `ai.Middleware`, `ai.WithUse`, `Hooks` (Generate/Model/Tool), built-ins (`Retry`, `Fallback`, `ToolApproval`, `Filesystem`, `Skills`) | | Flows & HTTP | [references/flows-and-http.md](references/flows-and-http.md) | `DefineFlow`, `DefineStreamingFlow`, `genkit.Handler`, HTTP serving | | Model Providers | [references/providers.md](references/providers.md) | Google AI, Vertex AI, Anthropic, OpenAI-compatible, Ollama setup |

Agents (Experimental)

Genkit Go has an **experimental** agent API for persistent, multi-turn conversations (sessions, snapshots, interrupts, branching, background execution). It is gated: initialize with `genkit.Init(ctx, genkit.WithExperimental())` or the constructors panic. Server constructors come from `genkit/exp` (aliased `genkitx`); types and options from `ai/exp` (aliased `aix`); session stores from `ai/exp/localstore`.

• **Agent or flow?** If the task is conversational, multi-turn, or described as "an agent", "assistant", or "chatbot", build it with `genkitx.DefineAgent` rather than hand-rolling a `Generate` + tools loop in a flow. Reach for a plain flow only for single-shot, stateless generation.

For details see:

• [Agents](references/agents.md): defining/serving an agent, running turns, and client- vs server-managed state (start here).
• [Sessions & persistence](references/agents-sessions.md): session stores (`localstore.NewInMemorySessionStore`/`NewFileSessionStore`) and snapshots.
• [Human-in-the-loop / interrupts](references/agents-human-in-the-loop.md): pausing for approval/input and resuming.
• [Branching](references/agents-branching.md): forking a conversation from a snapshot.
• [Background agents](references/agents-background.md): detaching long-running turns and polling.
• [Working with state](references/agents-state.md): typed custom session state, streamed as JSON patches.
• [Artifacts](references/agents-artifacts.md): producing and reading named deliverables.
• [Multi-agent orchestration](references/agents-multi-agent.md): delegating to sub-agents.
• [Advanced custom agents](references/agents-custom.md): `DefineCustomAgent` for full turn control.
• [Deploying agents](references/agents-deployment.md): serving agents over HTTP with `genkit.Handler`.

Genkit CLI (recommended)

`genkit start` unintrusively wraps any Go program that uses the Genkit library, running it unchanged while capturing traces from every Genkit action so you can prove tools were actually called and inspect model I/O from the terminal, even for headless checks. It forwards stdio, so interactive CLI tools that rely on stdin/stdout work without issues. Running the app directly (`go run .`) skips trace capture, so you're debugging blind. Check install with `genkit --version`.

**Installation:**

curl -sL cli.genkit.dev | bash

**Primary pattern (default):** prefix `genkit start --` to your normal run command. This collects telemetry from any Genkit code your program runs, whether triggered from the dev UI, your own web server/web UI, or a plain script. Starts the Developer UI (usually http://localhost:4000) for running flows, model and agent playground, and browsing traces:

genkit start -- go run .
genkit start --noui -- go run .   # same, without the Dev UI (still a persistent server)
genkit start -o -- go run .       # also opens the browser

`genkit start` runs until you stop it with Ctrl+C. That is expected and correct for the common cases: a server your web/mobile app calls, or an interactive CLI you exit yourself. `--noui` only drops the Dev UI; it is **not** a one-shot command and will not exit on its own. Do **not** use `genkit start` as a blocking step in automated/non-interactive contexts; use `flow:run` (below) for that.

**Non-interactive use (agents/CI):** add the global `--non-interactive` flag before `--` so the CLI uses defaults and never blocks on a prompt (e.g. the first-run analytic