feat: improve support for instance ID tag

internal/config/validationutil/validationutil.go

@@ -0,0 +1,33 @@
+package validationutil
+
+import (
+	"errors"
+	"fmt"
+	"regexp"
+)
+
+var (
+	IDMaxLen        = 50                                       // maximum length of an ID
+	sanitizeIDRegex = regexp.MustCompile(`[^a-zA-Z0-9_\-\.]+`) // matches invalid characters in an ID
+	idRegex         = regexp.MustCompile(`[a-zA-Z0-9_\-\.]*`)  // matches a valid ID (including empty string)
+)
+
+func SanitizeID(id string) string {
+	return sanitizeIDRegex.ReplaceAllString(id, "_")
+}
+
+// ValidateID checks if an ID is valid.
+// It returns an error if the ID contains invalid characters, is empty, or is too long.
+// The maxLen parameter is the maximum length of the ID. If maxLen is 0, the ID length is not checked.
+func ValidateID(id string, maxLen int) error {
+	if !idRegex.MatchString(id) {
+		return errors.New("contains invalid characters")
+	}
+	if len(id) == 0 {
+		return errors.New("empty")
+	}
+	if maxLen > 0 && len(id) > maxLen {
+		return fmt.Errorf("too long (> %d chars)", maxLen)
+	}
+	return nil
+}