Add config export via flag and API

api/endpoints_config.go

@@ -0,0 +1,24 @@
+package api
+
+import (
+	"github.com/safing/portbase/config"
+)
+
+func registerConfigEndpoints() error {
+	if err := RegisterEndpoint(Endpoint{
+		Path:        "config/options",
+		Read:        PermitAnyone,
+		MimeType:    MimeTypeJSON,
+		StructFunc:  listConfig,
+		Name:        "Export Configuration Options",
+		Description: "Returns a list of all registered configuration options and their metadata. This does not include the current active or default settings.",
+	}); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func listConfig(ar *Request) (i interface{}, err error) {
+	return config.ExportOptions(), nil
+}

config/main.go

@@ -1,7 +1,9 @@
 package config
 
 import (
+	"encoding/json"
 	"errors"
+	"flag"
 	"os"
 	"path/filepath"
 
@@ -17,6 +19,8 @@ const (
 var (
 	module   *modules.Module
 	dataRoot *utils.DirStructure
+
+	exportConfig bool
 )
 
 // SetDataRoot sets the data root from which the updates module derives its paths.
@@ -29,6 +33,8 @@ func SetDataRoot(root *utils.DirStructure) {
 func init() {
 	module = modules.Register("config", prep, start, nil, "database")
 	module.RegisterEvent(configChangeEvent)
+
+	flag.BoolVar(&exportConfig, "export-config-options", false, "export configuration registry and exit")
 }
 
 func prep() error {
@@ -37,6 +43,10 @@ func prep() error {
 		return errors.New("data root is not set")
 	}
 
+	if exportConfig {
+		modules.SetCmdLineOperation(exportConfigCmd)
+	}
+
 	return nil
 }
 
@@ -54,3 +64,13 @@ func start() error {
 	}
 	return nil
 }
+
+func exportConfigCmd() error {
+	data, err := json.MarshalIndent(ExportOptions(), "", "  ")
+	if err != nil {
+		return err
+	}
+
+	_, err = os.Stdout.Write(data)
+	return err
+}

config/registry.go

@@ -3,6 +3,7 @@ package config
 import (
 	"fmt"
 	"regexp"
+	"sort"
 	"strings"
 	"sync"
 )
@@ -29,6 +30,23 @@ func ForEachOption(fn func(opt *Option) error) error {
 	return nil
 }
 
+// ExportOptions exports the registered options. The returned data must be
+// treated as immutable.
+// The data does not include the current active or default settings.
+func ExportOptions() []*Option {
+	optionsLock.RLock()
+	defer optionsLock.RUnlock()
+
+	// Copy the map into a slice.
+	opts := make([]*Option, 0, len(options))
+	for _, opt := range options {
+		opts = append(opts, opt)
+	}
+
+	sort.Sort(sortByKey(opts))
+	return opts
+}
+
 // GetOption returns the option with name or an error
 // if the option does not exist. The caller should lock
 // the returned option itself for further processing.