cli/compose: use strings.Cut

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

cli/compose/convert/service.go

@@ -427,11 +427,11 @@ func uint32Ptr(value uint32) *uint32 {
 // convertExtraHosts converts <host>:<ip> mappings to SwarmKit notation:
 // "IP-address hostname(s)". The original order of mappings is preserved.
 func convertExtraHosts(extraHosts composetypes.HostsList) []string {
-	hosts := []string{}
+	hosts := make([]string, 0, len(extraHosts))
 	for _, hostIP := range extraHosts {
-		if v := strings.SplitN(hostIP, ":", 2); len(v) == 2 {
+		if hostName, ipAddr, ok := strings.Cut(hostIP, ":"); ok {
 			// Convert to SwarmKit notation: IP-address hostname(s)
-			hosts = append(hosts, fmt.Sprintf("%s %s", v[1], v[0]))
+			hosts = append(hosts, ipAddr+" "+hostName)
 		}
 	}
 	return hosts

cli/compose/loader/loader.go

@@ -829,21 +829,20 @@ func transformListOrMapping(listOrMapping interface{}, sep string, allowNil bool
 }
 
 func transformMappingOrList(mappingOrList interface{}, sep string, allowNil bool) interface{} {
-	switch value := mappingOrList.(type) {
+	switch values := mappingOrList.(type) {
 	case map[string]interface{}:
-		return toMapStringString(value, allowNil)
-	case ([]interface{}):
+		return toMapStringString(values, allowNil)
+	case []interface{}:
 		result := make(map[string]interface{})
-		for _, value := range value {
-			parts := strings.SplitN(value.(string), sep, 2)
-			key := parts[0]
+		for _, v := range values {
+			key, val, hasValue := strings.Cut(v.(string), sep)
 			switch {
-			case len(parts) == 1 && allowNil:
+			case !hasValue && allowNil:
 				result[key] = nil
-			case len(parts) == 1 && !allowNil:
+			case !hasValue && !allowNil:
 				result[key] = ""
 			default:
-				result[key] = parts[1]
+				result[key] = val
 			}
 		}
 		return result

cli/compose/template/template.go

@@ -239,9 +239,9 @@ func matchGroups(matches []string, pattern *regexp.Regexp) map[string]string {
 //
 // If the separator is not found, return the string itself, followed by an empty string.
 func partition(s, sep string) (string, string) {
-	if strings.Contains(s, sep) {
-		parts := strings.SplitN(s, sep, 2)
-		return parts[0], parts[1]
-	}
+	k, v, ok := strings.Cut(s, sep)
+	if !ok {
 		return s, ""
 	}
+	return k, v
+}