bind: Add JSON formatting option to DescribeFlags (#370)

This is useful for exporting or recording config settings.

bind/describe.go

@@ -0,0 +1,62 @@
+// Copyright 2023 Sauce Labs Inc. All rights reserved.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package bind
+
+import (
+	"encoding/json"
+	"fmt"
+	"sort"
+	"strings"
+
+	"github.com/spf13/pflag"
+)
+
+type DescribeFormat int
+
+const (
+	Plain DescribeFormat = iota
+	JSON
+)
+
+func DescribeFlags(fs *pflag.FlagSet, showHidden bool, format DescribeFormat) (string, error) {
+	args := make(map[string]any, fs.NFlag())
+	keys := make([]string, 0, fs.NFlag())
+
+	fs.VisitAll(func(flag *pflag.Flag) {
+		if flag.Name == "help" {
+			return
+		}
+
+		if flag.Hidden && !showHidden {
+			return
+		}
+
+		if flag.Value.Type() == "bool" {
+			args[flag.Name] = flag.Value
+		} else {
+			args[flag.Name] = strings.Trim(flag.Value.String(), "[]")
+		}
+
+		keys = append(keys, flag.Name)
+	})
+
+	sort.Strings(keys)
+
+	switch format {
+	case Plain:
+		var b strings.Builder
+		for _, name := range keys {
+			b.WriteString(fmt.Sprintf("%s=%s\n", name, args[name]))
+		}
+		return b.String(), nil
+	case JSON:
+		encoded, err := json.Marshal(args)
+		return string(encoded), err
+	default:
+		return "", fmt.Errorf("unknown format requested")
+	}
+}

bind/describe_test.go

@@ -0,0 +1,156 @@
+// Copyright 2023 Sauce Labs Inc. All rights reserved.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package bind
+
+import (
+	"testing"
+
+	"github.com/spf13/pflag"
+)
+
+func TestDescribeFlagsAsPlain(t *testing.T) {
+	tests := map[string]struct {
+		input      map[string]interface{}
+		expected   string
+		isErr      bool
+		isHidden   bool
+		showHidden bool
+	}{
+		"keys are sorted": {
+			input:    map[string]interface{}{"foo": false, "bar": true},
+			expected: "bar=true\nfoo=false\n",
+			isErr:    false,
+		},
+		"bool is correctly formatted": {
+			input:    map[string]interface{}{"key": false},
+			expected: "key=false\n",
+			isErr:    false,
+		},
+		"string is correctly formatted": {
+			input:    map[string]interface{}{"key": "val"},
+			expected: "key=val\n",
+			isErr:    false,
+		},
+		"help is not shown": {
+			input:    map[string]interface{}{"key": false, "help": true},
+			expected: "key=false\n",
+			isErr:    false,
+		},
+		"hidden is shown": {
+			input:      map[string]interface{}{"key": false},
+			expected:   "key=false\n",
+			isErr:      false,
+			isHidden:   true,
+			showHidden: true,
+		},
+		"hidden is not shown": {
+			input:      map[string]interface{}{"key": false},
+			expected:   ``,
+			isErr:      false,
+			isHidden:   true,
+			showHidden: false,
+		},
+	}
+
+	for name, tc := range tests {
+		fs := pflag.NewFlagSet("flags", pflag.ContinueOnError)
+
+		for k, v := range tc.input {
+			switch val := v.(type) {
+			case bool:
+				fs.Bool(k, val, "")
+			case string:
+				fs.String(k, val, "")
+			}
+
+			if tc.isHidden {
+				err := fs.MarkHidden(k)
+				if err != nil {
+					t.Errorf("%s: test setup failed: %s", name, err)
+				}
+			}
+		}
+		result, err := DescribeFlags(fs, tc.showHidden, Plain)
+
+		if (err != nil) != tc.isErr {
+			t.Errorf("%s: expected error: %v, got %s", name, tc.isErr, err)
+		}
+
+		if result != tc.expected {
+			t.Errorf("%s: expected %s, got %s", name, tc.expected, result)
+		}
+	}
+}
+
+func TestDescribeFlagsAsJSON(t *testing.T) {
+	tests := map[string]struct {
+		input      map[string]interface{}
+		expected   string
+		isErr      bool
+		isHidden   bool
+		showHidden bool
+	}{
+		"bool is not quoted": {
+			input:    map[string]interface{}{"key": false},
+			expected: `{"key":false}`,
+			isErr:    false,
+		},
+		"help is not shown": {
+			input:    map[string]interface{}{"key": false, "help": true},
+			expected: `{"key":false}`,
+			isErr:    false,
+		},
+		"hidden is shown": {
+			input:      map[string]interface{}{"key": false},
+			expected:   `{"key":false}`,
+			isErr:      false,
+			isHidden:   true,
+			showHidden: true,
+		},
+		"hidden is not shown": {
+			input:      map[string]interface{}{"key": false},
+			expected:   `{}`,
+			isErr:      false,
+			isHidden:   true,
+			showHidden: false,
+		},
+		"string is quoted": {
+			input:    map[string]interface{}{"key": "val"},
+			expected: `{"key":"val"}`,
+			isErr:    false,
+		},
+	}
+
+	for name, tc := range tests {
+		fs := pflag.NewFlagSet("flags", pflag.ContinueOnError)
+
+		for k, v := range tc.input {
+			switch val := v.(type) {
+			case bool:
+				fs.Bool(k, val, "")
+			case string:
+				fs.String(k, val, "")
+			}
+
+			if tc.isHidden {
+				err := fs.MarkHidden(k)
+				if err != nil {
+					t.Errorf("%s: test setup failed: %s", name, err)
+				}
+			}
+		}
+		result, err := DescribeFlags(fs, tc.showHidden, JSON)
+
+		if (err != nil) != tc.isErr {
+			t.Errorf("%s: expected error: %v, got %s", name, tc.isErr, err)
+		}
+
+		if result != tc.expected {
+			t.Errorf("%s: expected %s, got %s", name, tc.expected, result)
+		}
+	}
+}

bind/flag.go

@@ -7,7 +7,6 @@
 package bind
 
 import (
-	"fmt"
 	"net/netip"
 	"net/url"
 	"os"
@@ -328,14 +327,3 @@ func MarkFlagFilename(cmd *cobra.Command, names ...string) {
 		}
 	}
 }
-
-func DescribeFlags(fs *pflag.FlagSet) string {
-	var b strings.Builder
-	fs.VisitAll(func(flag *pflag.Flag) {
-		if flag.Hidden || flag.Name == "help" {
-			return
-		}
-		b.WriteString(fmt.Sprintf("%s=%s\n", flag.Name, strings.Trim(flag.Value.String(), "[]")))
-	})
-	return b.String()
-}

cmd/forwarder/httpbin/httpbin.go

@@ -24,7 +24,10 @@ type command struct {
 }
 
 func (c *command) RunE(cmd *cobra.Command, _ []string) error {
-	config := bind.DescribeFlags(cmd.Flags())
+	config, err := bind.DescribeFlags(cmd.Flags(), false, bind.Plain)
+	if err != nil {
+		return err
+	}
 
 	if f := c.logConfig.File; f != nil {
 		defer f.Close()

cmd/forwarder/pac/server/server.go

@@ -31,7 +31,10 @@ type command struct {
 }
 
 func (c *command) RunE(cmd *cobra.Command, _ []string) error {
-	config := bind.DescribeFlags(cmd.Flags())
+	config, err := bind.DescribeFlags(cmd.Flags(), false, bind.Plain)
+	if err != nil {
+		return err
+	}
 
 	if f := c.logConfig.File; f != nil {
 		defer f.Close()

cmd/forwarder/run/run.go

@@ -43,7 +43,10 @@ type command struct {
 }
 
 func (c *command) RunE(cmd *cobra.Command, _ []string) error {
-	config := bind.DescribeFlags(cmd.Flags())
+	config, err := bind.DescribeFlags(cmd.Flags(), false, bind.Plain)
+	if err != nil {
+		return err
+	}
 
 	if f := c.logConfig.File; f != nil {
 		defer f.Close()