Add token rotation

internal/config/flags.go

@@ -20,6 +20,7 @@ type Set struct {
 	specs     []*spec
 	longs     map[string]bool
 	shorts    map[string]bool
+	fromEnv   map[string]bool
 }
 
 type spec struct {
@@ -35,6 +36,7 @@ func NewSet(name, envPrefix string) *Set {
 		envPrefix: envPrefix,
 		longs:     map[string]bool{},
 		shorts:    map[string]bool{},
+		fromEnv:   map[string]bool{},
 	}
 	s.fs.Usage = func() {}
 	return s
@@ -192,6 +194,7 @@ func (s *Set) applyEnv() error {
 		if err := s.fs.Set(sp.long, v); err != nil {
 			return fmt.Errorf("%s: %w", s.envName(sp.long), err)
 		}
+		s.fromEnv[sp.long] = true
 	}
 	return nil
 }
@@ -208,6 +211,31 @@ func (s *Set) Parse(args []string) error {
 	return s.fs.Parse(args)
 }
 
+// Changed reports whether an option was given on the command line.
+//
+// Values picked up from the environment do not count: a command that acts only
+// on the options you actually typed must not quietly act on a SEND_ variable
+// exported for the server.
+func (s *Set) Changed(long string) bool {
+	if s.fromEnv[long] {
+		return false
+	}
+	short := ""
+	for _, sp := range s.specs {
+		if sp.long == long {
+			short = sp.short
+			break
+		}
+	}
+	given := false
+	s.fs.Visit(func(f *flag.Flag) {
+		if f.Name == long || (short != "" && f.Name == short) {
+			given = true
+		}
+	})
+	return given
+}
+
 // PrintUsage renders the options in the "-x, --xxx" form the convention implies.
 func (s *Set) PrintUsage(w io.Writer, header string) {
 	fmt.Fprint(w, header)