at-container-registry/cmd/credential-helper/cmd_configure.go

package main

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"github.com/charmbracelet/huh"
	"github.com/spf13/cobra"
)

func newConfigureDockerCmd() *cobra.Command {
	return &cobra.Command{
		Use:   "configure-docker",
		Short: "Configure Docker to use this credential helper",
		Long:  "Adds or updates the credHelpers entry in ~/.docker/config.json\nfor all configured registries.",
		RunE:  runConfigureDocker,
	}
}

func runConfigureDocker(cmd *cobra.Command, args []string) error {
	cfg, err := loadConfig()
	if err != nil {
		return fmt.Errorf("loading config: %w", err)
	}

	if len(cfg.Registries) == 0 {
		fmt.Fprintf(os.Stderr, "No registries configured.\n")
		fmt.Fprintf(os.Stderr, "Run: docker-credential-atcr login\n")
		return nil
	}

	// Collect registry hosts
	var hosts []string
	for url := range cfg.Registries {
		host := strings.TrimPrefix(url, "https://")
		host = strings.TrimPrefix(host, "http://")
		hosts = append(hosts, host)
	}

	dockerConfigPath := getDockerConfigPath()

	// Load existing Docker config
	dockerCfg := loadDockerConfig()
	if dockerCfg == nil {
		dockerCfg = make(map[string]any)
	}

	// Get or create credHelpers
	helpers, ok := dockerCfg["credHelpers"]
	if !ok {
		helpers = make(map[string]any)
	}
	helpersMap, ok := helpers.(map[string]any)
	if !ok {
		helpersMap = make(map[string]any)
	}

	// Check what needs to change
	var toAdd []string
	for _, host := range hosts {
		current, exists := helpersMap[host]
		if !exists || current != "atcr" {
			toAdd = append(toAdd, host)
		}
	}

	if len(toAdd) == 0 {
		fmt.Printf("Docker is already configured for all registries.\n")
		return nil
	}

	fmt.Printf("Will update %s:\n", dockerConfigPath)
	for _, host := range toAdd {
		fmt.Printf("  + credHelpers[%q] = \"atcr\"\n", host)
	}
	fmt.Println()

	var confirm bool
	err = huh.NewConfirm().
		Title("Apply changes?").
		Value(&confirm).
		Run()
	if err != nil || !confirm {
		fmt.Fprintf(os.Stderr, "Cancelled.\n")
		return nil
	}

	// Apply changes
	for _, host := range toAdd {
		helpersMap[host] = "atcr"
	}
	dockerCfg["credHelpers"] = helpersMap

	// Remove conflicting credsStore if it exists and we're adding credHelpers
	if _, hasStore := dockerCfg["credsStore"]; hasStore {
		fmt.Fprintf(os.Stderr, "Note: credsStore is set — credHelpers takes precedence for configured registries.\n")
	}

	if err := saveDockerConfig(dockerConfigPath, dockerCfg); err != nil {
		return fmt.Errorf("saving Docker config: %w", err)
	}

	fmt.Printf("Docker configured successfully.\n")
	return nil
}

// getDockerConfigPath returns the path to Docker's config.json
func getDockerConfigPath() string {
	// Check DOCKER_CONFIG env var first
	if dir := os.Getenv("DOCKER_CONFIG"); dir != "" {
		return filepath.Join(dir, "config.json")
	}

	homeDir, err := os.UserHomeDir()
	if err != nil {
		return ""
	}
	return filepath.Join(homeDir, ".docker", "config.json")
}

// loadDockerConfig loads Docker's config.json as a generic map
func loadDockerConfig() map[string]any {
	path := getDockerConfigPath()
	if path == "" {
		return nil
	}

	data, err := os.ReadFile(path)
	if err != nil {
		return nil
	}

	var config map[string]any
	if err := json.Unmarshal(data, &config); err != nil {
		return nil
	}

	return config
}

// saveDockerConfig writes Docker's config.json
func saveDockerConfig(path string, config map[string]any) error {
	// Ensure directory exists
	dir := filepath.Dir(path)
	if err := os.MkdirAll(dir, 0700); err != nil {
		return err
	}

	data, err := json.MarshalIndent(config, "", "\t")
	if err != nil {
		return err
	}
	data = append(data, '\n')

	return os.WriteFile(path, data, 0600)
}