Add example environment configuration and Docker Compose setup

- Introduced a new `.env.example` file to provide a template for environment variables used by the Scratchbox server.
- Added a `docker-compose.example.yml` file to facilitate easy deployment of the Scratchbox service with Docker.
- Updated `docker-entrypoint.sh` to enforce environment variable settings for server configuration.
- Removed the generation of a config key file from the workflow, simplifying the configuration process.
- Adjusted the README.md to reflect changes in configuration management and usage instructions.

cmd/scratchbox/main_test.go

@@ -32,18 +32,6 @@ func repoRoot(t *testing.T) string {
 	return filepath.Clean(filepath.Join(filepath.Dir(file), "..", ".."))
 }
 
-func writeConfigKeyFile(t *testing.T, configPath string) {
-	t.Helper()
-	keyPath := filepath.Join(filepath.Dir(configPath), "config.key")
-	key, err := config.GenerateEncryptionKey()
-	if err != nil {
-		t.Fatalf("GenerateEncryptionKey() error = %v", err)
-	}
-	if err := os.WriteFile(keyPath, []byte(key+"\n"), 0o600); err != nil {
-		t.Fatalf("WriteFile(config.key) error = %v", err)
-	}
-}
-
 func TestMainProcessSuccess(t *testing.T) {
 	t.Parallel()
 
@@ -77,7 +65,6 @@ security:
 	if err := os.WriteFile(cfgPath, []byte(cfg), 0o644); err != nil {
 		t.Fatalf("WriteFile() error = %v", err)
 	}
-	writeConfigKeyFile(t, cfgPath)
 
 	cmd := exec.Command(os.Args[0], "-test.run=TestMainHelperProcess")
 	cmd.Dir = repoRoot(t)
@@ -105,6 +92,75 @@ func TestMainProcessBadConfigFails(t *testing.T) {
 	}
 }
 
+func TestMainProcessMissingConfigAutoGenerates(t *testing.T) {
+	t.Parallel()
+
+	tmp := t.TempDir()
+	cfgPath := filepath.Join(tmp, "nested", "config.yaml")
+
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+
+	cmd := exec.CommandContext(ctx, os.Args[0], "-test.run=TestMainHelperProcess")
+	cmd.Dir = repoRoot(t)
+	cmd.Env = append(os.Environ(),
+		"GO_WANT_MAIN_HELPER=1",
+		"MAIN_HELPER_MODE=missing-config-autogen",
+		"MAIN_HELPER_CONFIG="+cfgPath,
+	)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("helper process failed: %v, output=%s", err, string(out))
+	}
+	if !strings.Contains(string(out), "Review and adjust it, then re-run the same command.") {
+		t.Fatalf("helper output missing expected guidance, output=%q", string(out))
+	}
+
+	raw, err := os.ReadFile(cfgPath)
+	if err != nil {
+		t.Fatalf("ReadFile(generated config) error = %v", err)
+	}
+	if !strings.Contains(string(raw), "server:") {
+		t.Fatalf("generated config missing expected section")
+	}
+}
+
+func TestMainProcessEnvSuccess(t *testing.T) {
+	t.Parallel()
+
+	tmp := t.TempDir()
+
+	cmd := exec.Command(os.Args[0], "-test.run=TestMainHelperProcess")
+	cmd.Dir = repoRoot(t)
+	cmd.Env = append(os.Environ(),
+		"GO_WANT_MAIN_HELPER=1",
+		"MAIN_HELPER_MODE=env-success",
+		"SCRATCHBOX_SERVER_LISTEN_ADDR=127.0.0.1:0",
+		"SCRATCHBOX_STORAGE_DATA_DIR="+filepath.Join(tmp, "data"),
+		"SCRATCHBOX_SECURITY_ALLOWED_IPS=",
+	)
+	if out, err := cmd.CombinedOutput(); err != nil {
+		t.Fatalf("helper process failed: %v, output=%s", err, string(out))
+	}
+}
+
+func TestServerConfigAndEnvMutuallyExclusive(t *testing.T) {
+	t.Parallel()
+
+	cmd := newRootCmd()
+	cmd.SetOut(io.Discard)
+	cmd.SetErr(io.Discard)
+	cmd.SetArgs([]string{"server", "--config", "config.yaml", "--env"})
+
+	err := cmd.Execute()
+	if err == nil {
+		t.Fatalf("expected error when both --config and --env are set")
+	}
+	if !strings.Contains(err.Error(), "none of the others can be") {
+		t.Fatalf("error = %q, want mutually exclusive flags error", err.Error())
+	}
+}
+
 func TestMainProcessStorageInitFails(t *testing.T) {
 	t.Parallel()
 
@@ -142,7 +198,6 @@ security:
 	if err := os.WriteFile(cfgPath, []byte(cfg), 0o644); err != nil {
 		t.Fatalf("WriteFile() error = %v", err)
 	}
-	writeConfigKeyFile(t, cfgPath)
 
 	cmd := exec.Command(os.Args[0], "-test.run=TestMainHelperProcess")
 	cmd.Dir = repoRoot(t)
@@ -181,6 +236,25 @@ func TestMainHelperProcess(t *testing.T) {
 		os.Args = []string{"scratchbox", "server", "--config", "/no/such/config.yaml"}
 		main()
 		os.Exit(0)
+	case "missing-config-autogen":
+		cfgPath := os.Getenv("MAIN_HELPER_CONFIG")
+		if cfgPath == "" {
+			os.Exit(2)
+		}
+		os.Args = []string{"scratchbox", "server", "--config", cfgPath}
+		main()
+		os.Exit(0)
+	case "env-success":
+		go func() {
+			time.Sleep(120 * time.Millisecond)
+			proc, err := os.FindProcess(os.Getpid())
+			if err == nil {
+				_ = proc.Signal(os.Interrupt)
+			}
+		}()
+		os.Args = []string{"scratchbox", "server", "--env"}
+		main()
+		os.Exit(0)
 	case "storage-fail":
 		cfgPath := os.Getenv("MAIN_HELPER_CONFIG")
 		os.Args = []string{"scratchbox", "server", "--config", cfgPath}
@@ -229,9 +303,6 @@ func TestGenerateConfigCommandWritesDefaultYAML(t *testing.T) {
 	if cfg.Storage.DataDir != "./data" {
 		t.Fatalf("storage.data_dir = %q, want %q", cfg.Storage.DataDir, "./data")
 	}
-	if cfg.Storage.EncryptionKeyFile != "config.key" {
-		t.Fatalf("storage.encryption_key_file = %q, want %q", cfg.Storage.EncryptionKeyFile, "config.key")
-	}
 	if cfg.Security.RateLimitUI.RequestsPerMinute != 360 {
 		t.Fatalf("security.rate_limit_ui.requests_per_minute = %d, want %d", cfg.Security.RateLimitUI.RequestsPerMinute, 360)
 	}
@@ -335,7 +406,6 @@ security:
 	if err := os.WriteFile(cfgPath, []byte(cfgRaw), 0o644); err != nil {
 		t.Fatalf("WriteFile() error = %v", err)
 	}
-	writeConfigKeyFile(t, cfgPath)
 
 	cfg, err := config.Load(cfgPath)
 	if err != nil {

cmd/scratchbox/server.go

@@ -2,11 +2,14 @@ package main
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"log"
 	"net/http"
 	"os"
 	"os/signal"
+	"path/filepath"
+	"strings"
 	"syscall"
 	"time"
 
@@ -20,21 +23,40 @@ import (
 
 func newServerCmd() *cobra.Command {
 	var configPath string
+	var useEnv bool
 
 	cmd := &cobra.Command{
 		Use:   "server",
 		Short: "Run the scratchbox service",
 		Args:  cobra.NoArgs,
 		RunE: func(_ *cobra.Command, _ []string) error {
-			return run(configPath)
+			return run(configPath, useEnv)
 		},
 	}
 	cmd.Flags().StringVarP(&configPath, "config", "c", "", "path to config file")
+	cmd.Flags().BoolVar(&useEnv, "env", false, "load config from SCRATCHBOX_* environment variables")
+	cmd.MarkFlagsMutuallyExclusive("config", "env")
 	return cmd
 }
 
-func run(configPath string) error {
-	cfg, err := config.Load(configPath)
+func run(configPath string, useEnv bool) error {
+	var (
+		cfg config.Config
+		err error
+	)
+	if useEnv {
+		cfg, err = config.LoadFromEnv()
+	} else {
+		generated, err := ensureConfigFile(configPath)
+		if err != nil {
+			return fmt.Errorf("config init failed: %w", err)
+		}
+		if generated {
+			fmt.Fprintf(os.Stdout, "Generated default config at %s\nReview and adjust it, then re-run the same command.\n", strings.TrimSpace(configPath))
+			return nil
+		}
+		cfg, err = config.Load(configPath)
+	}
 	if err != nil {
 		return fmt.Errorf("config load failed: %w", err)
 	}
@@ -100,3 +122,34 @@ func run(configPath string) error {
 	}
 	return nil
 }
+
+func ensureConfigFile(configPath string) (bool, error) {
+	path := strings.TrimSpace(configPath)
+	if path == "" {
+		return false, nil
+	}
+
+	info, err := os.Stat(path)
+	if err == nil {
+		if info.IsDir() {
+			return false, fmt.Errorf("config path %q is a directory", path)
+		}
+		return false, nil
+	}
+	if !errors.Is(err, os.ErrNotExist) {
+		return false, fmt.Errorf("stat config path %q: %w", path, err)
+	}
+
+	cfg := config.Default()
+	content, err := marshalYAMLWithComments(cfg)
+	if err != nil {
+		return false, fmt.Errorf("marshal default config: %w", err)
+	}
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return false, fmt.Errorf("create config dir: %w", err)
+	}
+	if err := os.WriteFile(path, content, 0o644); err != nil {
+		return false, fmt.Errorf("write default config: %w", err)
+	}
+	return true, nil
+}