feat(model): add UnsetValidation scheme

Author: juliusmh

model/alert_test.go

@@ -27,7 +27,7 @@ func TestAlertValidate(t *testing.T) {
 	cases := []struct {
 		alert  *Alert
 		err    string
-		scheme NameValidationScheme
+		scheme ValidationScheme
 	}{
 		{
 			alert: &Alert{

model/labels.go

@@ -110,7 +110,7 @@ func (ln LabelName) IsValid(scheme ValidationScheme) bool {
 	case UTF8Validation:
 		return utf8.ValidString(string(ln))
 	default:
-		panic(fmt.Sprintf("Invalid name validation scheme requested: %d", scheme))
+		panic(fmt.Sprintf("Invalid label name validation scheme requested: %d", scheme))
 	}
 }
 

model/metric.go

@@ -26,31 +26,77 @@ import (
 	"google.golang.org/protobuf/proto"
 )
 
-var (
-	// NameEscapingScheme defines the default way that names will be escaped when
-	// presented to systems that do not support UTF-8 names. If the Content-Type
-	// "escaping" term is specified, that will override this value.
-	// NameEscapingScheme should not be set to the NoEscaping value. That string
-	// is used in content negotiation to indicate that a system supports UTF-8 and
-	// has that feature enabled.
-	NameEscapingScheme = UnderscoreEscaping
-)
-
-// NameValidationScheme is a Go enum for determining how metric and label names will
+// NameEscapingScheme defines the default way that names will be escaped when
+// presented to systems that do not support UTF-8 names. If the Content-Type
+// "escaping" term is specified, that will override this value.
+// NameEscapingScheme should not be set to the NoEscaping value. That string
+// is used in content negotiation to indicate that a system supports UTF-8 and
+// has that feature enabled.
+var NameEscapingScheme = UnderscoreEscaping
+
+// ValidationScheme is a Go enum for determining how metric and label names will
 // be validated by this library.
 type ValidationScheme int
 
 const (
+	// UnsetValidation represents an undefined ValidationScheme.
+	// Should not be used in practice.
+	UnsetValidation ValidationScheme = iota
+
 	// LegacyValidation is a setting that requires that all metric and label names
 	// conform to the original Prometheus character requirements described by
 	// MetricNameRE and LabelNameRE.
-	LegacyValidation ValidationScheme = iota
+	LegacyValidation
 
 	// UTF8Validation only requires that metric and label names be valid UTF-8
 	// strings.
 	UTF8Validation
 )
 
+func (s ValidationScheme) String() string {
+	switch s {
+	case UnsetValidation:
+		return "unset"
+	case LegacyValidation:
+		return "legacy"
+	case UTF8Validation:
+		return "utf8"
+	default:
+		panic(fmt.Errorf("invalid ValidationScheme: %d", s))
+	}
+}
+
+// MarshalYAML implements the yaml.Marshaler interface.
+func (s ValidationScheme) MarshalYAML() (any, error) {
+	switch s {
+	case UnsetValidation:
+		return "", nil
+	case LegacyValidation, UTF8Validation:
+		return s.String(), nil
+	default:
+		panic(fmt.Errorf("invalid ValidationScheme: %d", s))
+	}
+}
+
+// UnmarshalYAML implements the yaml.Unmarshaler interface.
+func (s *ValidationScheme) UnmarshalYAML(unmarshal func(any) error) error {
+	var scheme string
+	if err := unmarshal(&scheme); err != nil {
+		return err
+	}
+	switch scheme {
+	case "":
+		// Don't change the value.
+	case "legacy":
+		*s = LegacyValidation
+	case "utf8":
+		*s = UTF8Validation
+	default:
+		return fmt.Errorf("invalid ValidationScheme: %q", scheme)
+	}
+	return nil
+}
+
 type EscapingScheme int
 
 const (
@@ -164,7 +210,7 @@ func IsValidMetricName(n LabelValue, scheme ValidationScheme) bool {
 		}
 		return utf8.ValidString(string(n))
 	default:
-		panic(fmt.Sprintf("Invalid name validation scheme requested: %d", scheme))
+		panic(fmt.Sprintf("Invalid metric name validation scheme requested: %d", scheme))
 	}
 }