google__adk-docs/examples/go/cloud-run/main.go

// Copyright 2025 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
	"context"
	"fmt"
	"log"
	"os"
	"strings"

	"google.golang.org/adk/agent/llmagent"
	"google.golang.org/adk/cmd/launcher/adk"
	"google.golang.org/adk/cmd/launcher/full"
	"google.golang.org/adk/server/restapi/services"

	"google.golang.org/adk/model/gemini"
	"google.golang.org/adk/tool"
	"google.golang.org/adk/tool/functiontool"
	"google.golang.org/genai"
)

type getCapitalCityArgs struct {
	Country string `json:"country" jsonschema:"The country for which to find the capital city."`
}

type getCapitalCityResult struct {
	Result       string `json:"result,omitempty"`
	ErrorMessage string `json:"error_message,omitempty"`
}

func getCapitalCity(ctx tool.Context, args getCapitalCityArgs) getCapitalCityResult {
	capitals := map[string]string{
		"united states": "Washington, D.C.",
		"canada":        "Ottawa",
		"france":        "Paris",
		"japan":         "Tokyo",
	}
	capital, ok := capitals[strings.ToLower(args.Country)]
	if !ok {
		result := fmt.Sprintf("Sorry, I couldn't find the capital for %s.", args.Country)
		return getCapitalCityResult{ErrorMessage: result}
	}

	return getCapitalCityResult{Result: capital}
}

func main() {
	ctx := context.Background()

	model, err := gemini.NewModel(ctx, "gemini-2.5-flash", &genai.ClientConfig{
		APIKey: os.Getenv("GOOGLE_API_KEY"),
	})
	if err != nil {
		log.Fatalf("Failed to create model: %v", err)
	}

	capitalTool, err := functiontool.New(
		functiontool.Config{
			Name:        "get_capital_city",
			Description: "Retrieves the capital city for a given country.",
		},
		getCapitalCity,
	)
	if err != nil {
		log.Fatalf("Failed to create function tool: %v", err)
	}

	agent, err := llmagent.New(llmagent.Config{
		Name:        "capital_agent",
		Model:       model,
		Description: "Agent to find the capital city of a country.",
		Instruction: "I can answer your questions about the capital city of a country.",
		Tools:       []tool.Tool{capitalTool},
	})
	if err != nil {
		log.Fatalf("Failed to create agent: %v", err)
	}

	config := &adk.Config{
		AgentLoader: services.NewSingleAgentLoader(agent),
	}

	l := full.NewLauncher()
	err = l.Execute(ctx, config, os.Args[1:])
	if err != nil {
		log.Fatalf("run failed: %v\n\n%s", err, l.CommandLineSyntax())
	}
}