cli/command/service: use strings.Cut

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/command/service/opts.go

@@ -93,17 +93,17 @@ func (opts *placementPrefOpts) String() string {
 // Note: in the future strategies other than "spread", may be supported,
 // as well as additional comma-separated options.
 func (opts *placementPrefOpts) Set(value string) error {
-	fields := strings.Split(value, "=")
-	if len(fields) != 2 {
+	strategy, arg, ok := strings.Cut(value, "=")
+	if !ok || strategy == "" {
 		return errors.New(`placement preference must be of the format "<strategy>=<arg>"`)
 	}
-	if fields[0] != "spread" {
-		return errors.Errorf("unsupported placement preference %s (only spread is supported)", fields[0])
+	if strategy != "spread" {
+		return errors.Errorf("unsupported placement preference %s (only spread is supported)", strategy)
 	}
 
 	opts.prefs = append(opts.prefs, swarm.PlacementPreference{
 		Spread: &swarm.SpreadOver{
-			SpreadDescriptor: fields[1],
+			SpreadDescriptor: arg,
 		},
 	})
 	opts.strings = append(opts.strings, value)
@@ -121,8 +121,11 @@ type ShlexOpt []string
 // Set the value
 func (s *ShlexOpt) Set(value string) error {
 	valueSlice, err := shlex.Split(value)
-	*s = ShlexOpt(valueSlice)
-	return err
+	if err != nil {
+		return err
+	}
+	*s = valueSlice
+	return nil
 }
 
 // Type returns the tyep of the value
@@ -475,10 +478,12 @@ func (opts *healthCheckOptions) toHealthConfig() (*container.HealthConfig, error
 //
 // This assumes input value (<host>:<ip>) has already been validated
 func convertExtraHostsToSwarmHosts(extraHosts []string) []string {
-	hosts := []string{}
+	hosts := make([]string, 0, len(extraHosts))
 	for _, extraHost := range extraHosts {
-		parts := strings.SplitN(extraHost, ":", 2)
-		hosts = append(hosts, fmt.Sprintf("%s %s", parts[1], parts[0]))
+		host, ip, ok := strings.Cut(extraHost, ":")
+		if ok {
+			hosts = append(hosts, ip+" "+host)
+		}
 	}
 	return hosts
 }
@@ -628,7 +633,7 @@ func (options *serviceOptions) makeEnv() ([]string, error) {
 	}
 	currentEnv := make([]string, 0, len(envVariables))
 	for _, env := range envVariables { // need to process each var, in order
-		k := strings.SplitN(env, "=", 2)[0]
+		k, _, _ := strings.Cut(env, "=")
 		for i, current := range currentEnv { // remove duplicates
 			if current == env {
 				continue // no update required, may hide this behind flag to preserve order of envVariables

cli/command/service/scale.go

@@ -43,7 +43,7 @@ func scaleArgs(cmd *cobra.Command, args []string) error {
 		return err
 	}
 	for _, arg := range args {
-		if parts := strings.SplitN(arg, "=", 2); len(parts) != 2 {
+		if k, v, ok := strings.Cut(arg, "="); !ok || k == "" || v == "" {
 			return errors.Errorf(
 				"Invalid scale specifier '%s'.\nSee '%s --help'.\n\nUsage:  %s\n\n%s",
 				arg,
@@ -62,8 +62,7 @@ func runScale(dockerCli command.Cli, options *scaleOptions, args []string) error
 	ctx := context.Background()
 
 	for _, arg := range args {
-		parts := strings.SplitN(arg, "=", 2)
-		serviceID, scaleStr := parts[0], parts[1]
+		serviceID, scaleStr, _ := strings.Cut(arg, "=")
 
 		// validate input arg scale number
 		scale, err := strconv.ParseUint(scaleStr, 10, 64)

cli/command/service/update.go

@@ -879,8 +879,8 @@ func removeConfigs(flags *pflag.FlagSet, spec *swarm.ContainerSpec, credSpecName
 }
 
 func envKey(value string) string {
-	kv := strings.SplitN(value, "=", 2)
-	return kv[0]
+	k, _, _ := strings.Cut(value, "=")
+	return k
 }
 
 func buildToRemoveSet(flags *pflag.FlagSet, flag string) map[string]struct{} {
@@ -1174,12 +1174,8 @@ func updateHosts(flags *pflag.FlagSet, hosts *[]string) error {
 	if flags.Changed(flagHostRemove) {
 		extraHostsToRemove := flags.Lookup(flagHostRemove).Value.(*opts.ListOpts).GetAll()
 		for _, entry := range extraHostsToRemove {
-			v := strings.SplitN(entry, ":", 2)
-			if len(v) > 1 {
-				toRemove = append(toRemove, hostMapping{IPAddr: v[1], Host: v[0]})
-			} else {
-				toRemove = append(toRemove, hostMapping{Host: v[0]})
-			}
+			hostName, ipAddr, _ := strings.Cut(entry, ":")
+			toRemove = append(toRemove, hostMapping{IPAddr: ipAddr, Host: hostName})
 		}
 	}