Add generate-config command to output default configuration in YAML format

cmd/scratchbox/generate_config.go

@@ -0,0 +1,58 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+	"gopkg.in/yaml.v3"
+
+	"scratchbox/internal/config"
+)
+
+func newGenerateConfigCmd() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "generate-config",
+		Short: "Print a default config YAML to stdout",
+		Args:  cobra.NoArgs,
+		RunE: func(cmd *cobra.Command, _ []string) error {
+			return writeDefaultConfig(cmd)
+		},
+	}
+	return cmd
+}
+
+func writeDefaultConfig(cmd *cobra.Command) error {
+	cfg := config.Config{
+		Server: config.ServerConfig{
+			ListenAddr: ":8080",
+		},
+		Limits: config.LimitsConfig{
+			MaxUploadSize: "100MB",
+			DefaultTTL:    "1h",
+		},
+		Storage: config.StorageConfig{
+			DataDir:         "./data",
+			CleanupInterval: "1m",
+		},
+		Security: config.SecurityConfig{
+			AllowedIPs:        []string{},
+			TrustProxyHeaders: false,
+			RateLimit: config.RateLimitConfig{
+				Enabled:           true,
+				RequestsPerMinute: 30,
+				Burst:             10,
+			},
+		},
+	}
+
+	b, err := yaml.Marshal(cfg)
+	if err != nil {
+		return fmt.Errorf("marshal default config: %w", err)
+	}
+
+	if _, err := cmd.OutOrStdout().Write(b); err != nil {
+		return fmt.Errorf("write default config: %w", err)
+	}
+
+	return nil
+}

cmd/scratchbox/main.go

@@ -26,5 +26,6 @@ func newRootCmd() *cobra.Command {
 		},
 	}
 	cmd.AddCommand(newServerCmd())
+	cmd.AddCommand(newGenerateConfigCmd())
 	return cmd
 }

cmd/scratchbox/main_test.go

@@ -19,6 +19,7 @@ import (
 	"scratchbox/internal/config"
 	httpapi "scratchbox/internal/http"
 	"scratchbox/internal/storage"
+	"gopkg.in/yaml.v3"
 )
 
 func repoRoot(t *testing.T) string {
@@ -205,6 +206,55 @@ func TestMainHelperProcess(t *testing.T) {
 	}
 }
 
+func TestGenerateConfigCommandWritesDefaultYAML(t *testing.T) {
+	t.Parallel()
+
+	cmd := newRootCmd()
+	var out bytes.Buffer
+	cmd.SetOut(&out)
+	cmd.SetErr(io.Discard)
+	cmd.SetArgs([]string{"generate-config"})
+
+	if err := cmd.Execute(); err != nil {
+		t.Fatalf("Execute() error = %v", err)
+	}
+
+	if out.Len() == 0 {
+		t.Fatalf("generate-config output is empty")
+	}
+
+	var cfg config.Config
+	if err := yaml.Unmarshal(out.Bytes(), &cfg); err != nil {
+		t.Fatalf("yaml.Unmarshal() error = %v", err)
+	}
+
+	if cfg.Server.ListenAddr != ":8080" {
+		t.Fatalf("server.listen_addr = %q, want %q", cfg.Server.ListenAddr, ":8080")
+	}
+	if cfg.Limits.MaxUploadSize != "100MB" {
+		t.Fatalf("limits.max_upload_size = %q, want %q", cfg.Limits.MaxUploadSize, "100MB")
+	}
+	if cfg.Storage.DataDir != "./data" {
+		t.Fatalf("storage.data_dir = %q, want %q", cfg.Storage.DataDir, "./data")
+	}
+	if cfg.Security.RateLimit.RequestsPerMinute != 30 {
+		t.Fatalf("security.rate_limit.requests_per_minute = %d, want %d", cfg.Security.RateLimit.RequestsPerMinute, 30)
+	}
+}
+
+func TestGenerateConfigCommandRejectsUnexpectedArgs(t *testing.T) {
+	t.Parallel()
+
+	cmd := newRootCmd()
+	cmd.SetOut(io.Discard)
+	cmd.SetErr(io.Discard)
+	cmd.SetArgs([]string{"generate-config", "extra"})
+
+	if err := cmd.Execute(); err == nil {
+		t.Fatalf("expected error for unexpected args")
+	}
+}
+
 func TestLiveServerEndToEndHTTP(t *testing.T) {
 	tmp := t.TempDir()
 	cfgPath := filepath.Join(tmp, "config.yaml")