Consistently use flag constants in error messages

When formatting an error from viper.BindPFlag, use the string constant
defined for the flag in the error message. This way if the flag name
changes, any error messages will be in sync.

v2/cmd/pi/client.go

@@ -53,16 +53,16 @@ func NewClientCmd() (*cobra.Command, error) {
 	clientCmd.PersistentFlags().Bool(InsecureFlagName, false, "Disable TLS for gRPC connection to Pi Service")
 	clientCmd.PersistentFlags().StringToString(HeaderFlagName, nil, "An optional header key=value to add to Pi Service request metadata; can be repeated")
 	if err := viper.BindPFlag(CountFlagName, clientCmd.PersistentFlags().Lookup(CountFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind count pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", CountFlagName, err)
 	}
 	if err := viper.BindPFlag(MaxTimeoutFlagName, clientCmd.PersistentFlags().Lookup(MaxTimeoutFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind max-timeout pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", MaxTimeoutFlagName, err)
 	}
 	if err := viper.BindPFlag(AuthorityFlagName, clientCmd.PersistentFlags().Lookup(AuthorityFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind authority pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", AuthorityFlagName, err)
 	}
 	if err := viper.BindPFlag(InsecureFlagName, clientCmd.PersistentFlags().Lookup(InsecureFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind insecure pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", InsecureFlagName, err)
 	}
 	if err := viper.BindPFlag(HeaderFlagName, clientCmd.PersistentFlags().Lookup(HeaderFlagName)); err != nil {
 		return nil, fmt.Errorf("failed to bind %s pflag: %w", HeaderFlagName, err)

v2/cmd/pi/root.go

@@ -53,31 +53,31 @@ func NewRootCmd() (*cobra.Command, error) {
 	rootCmd.PersistentFlags().String(TLSCertFlagName, "", "An optional TLS certificate to use")
 	rootCmd.PersistentFlags().String(TLSKeyFlagName, "", "An optional TLS private key to use")
 	if err := viper.BindPFlag(VerboseFlagName, rootCmd.PersistentFlags().Lookup(VerboseFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind verbose pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", VerboseFlagName, err)
 	}
 	if err := viper.BindPFlag(PrettyFlagName, rootCmd.PersistentFlags().Lookup(PrettyFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind pretty pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", PrettyFlagName, err)
 	}
 	if err := viper.BindPFlag(OpenTelemetryTargetFlagName, rootCmd.PersistentFlags().Lookup(OpenTelemetryTargetFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind otlp-target pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", OpenTelemetryTargetFlagName, err)
 	}
 	if err := viper.BindPFlag(OpenTelemetryInsecureFlagName, rootCmd.PersistentFlags().Lookup(OpenTelemetryInsecureFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind otlp-insecure pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", OpenTelemetryInsecureFlagName, err)
 	}
 	if err := viper.BindPFlag(OpenTelemetryAuthorityFlagName, rootCmd.PersistentFlags().Lookup(OpenTelemetryAuthorityFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind otlp-authority pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", OpenTelemetryAuthorityFlagName, err)
 	}
 	if err := viper.BindPFlag(OpenTelemetrySamplingRatioFlagName, rootCmd.PersistentFlags().Lookup(OpenTelemetrySamplingRatioFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind otlp-sampling-ratio pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", OpenTelemetrySamplingRatioFlagName, err)
 	}
 	if err := viper.BindPFlag(CACertFlagName, rootCmd.PersistentFlags().Lookup(CACertFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind cacert pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", CACertFlagName, err)
 	}
 	if err := viper.BindPFlag(TLSCertFlagName, rootCmd.PersistentFlags().Lookup(TLSCertFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind cert pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", TLSCertFlagName, err)
 	}
 	if err := viper.BindPFlag(TLSKeyFlagName, rootCmd.PersistentFlags().Lookup(TLSKeyFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind key pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", TLSKeyFlagName, err)
 	}
 	serverCmd, err := NewServerCmd()
 	if err != nil {

v2/cmd/pi/server.go

@@ -58,25 +58,25 @@ A single decimal digit of pi will be returned per request. An optional Redis DB
 	serverCmd.PersistentFlags().String(RESTAuthorityFlagName, "", "Set the Authority header for REST/gRPC gateway communication")
 	serverCmd.PersistentFlags().Bool("xds", false, "Enable xDS for PiService; requires an xDS environment")
 	if err := viper.BindPFlag(RESTAddressFlagName, serverCmd.PersistentFlags().Lookup(RESTAddressFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind rest-address pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", RESTAddressFlagName, err)
 	}
 	if err := viper.BindPFlag(RedisTargetFlagName, serverCmd.PersistentFlags().Lookup(RedisTargetFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind redis-target pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", RedisTargetFlagName, err)
 	}
 	if err := viper.BindPFlag(TagFlagName, serverCmd.PersistentFlags().Lookup(TagFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind tag pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", TagFlagName, err)
 	}
 	if err := viper.BindPFlag(AnnotationFlagName, serverCmd.PersistentFlags().Lookup(AnnotationFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind annotation pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", AnnotationFlagName, err)
 	}
 	if err := viper.BindPFlag(MutualTLSFlagName, serverCmd.PersistentFlags().Lookup(MutualTLSFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind label pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", MutualTLSFlagName, err)
 	}
 	if err := viper.BindPFlag(RESTAuthorityFlagName, serverCmd.PersistentFlags().Lookup(RESTAuthorityFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind rest-authority pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", RESTAuthorityFlagName, err)
 	}
 	if err := viper.BindPFlag(XDSFlagName, serverCmd.PersistentFlags().Lookup(XDSFlagName)); err != nil {
-		return nil, fmt.Errorf("failed to bind xds pflag: %w", err)
+		return nil, fmt.Errorf("failed to bind %s pflag: %w", XDSFlagName, err)
 	}
 	return serverCmd, nil
 }