Add JSON schema support

cmd/sing-box/cmd_schema.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"context"
+	"os"
+	"reflect"
+
+	"github.com/sagernet/sing-box/include"
+	"github.com/sagernet/sing-box/log"
+	"github.com/sagernet/sing-box/option"
+	"github.com/sagernet/sing-box/schema"
+
+	"github.com/spf13/cobra"
+)
+
+var commandSchemaFlagOutput string
+
+var commandSchema = &cobra.Command{
+	Use:   "schema",
+	Short: "Generate configuration JSON schema",
+	Args:  cobra.NoArgs,
+	Run: func(cmd *cobra.Command, args []string) {
+		err := generateSchema()
+		if err != nil {
+			log.Fatal(err)
+		}
+	},
+}
+
+func init() {
+	commandSchema.Flags().StringVarP(&commandSchemaFlagOutput, "output", "o", "", "write schema to file instead of stdout")
+	mainCommand.AddCommand(commandSchema)
+}
+
+func generateSchema() error {
+	content, err := schema.Generate(include.Context(context.Background()), reflect.TypeFor[option.Options]())
+	if err != nil {
+		return err
+	}
+	if commandSchemaFlagOutput != "" {
+		return os.WriteFile(commandSchemaFlagOutput, content, 0o644)
+	}
+	_, err = os.Stdout.Write(content)
+	return err
+}