Change default validation scheme to UTF8Validation (prometheus#724)

fixes prometheus#723

Signed-off-by: Owen Williams <owen.williams@grafana.com>

Author: ywwg

model/alert_test.go

@@ -22,6 +22,11 @@ import (
 )
 
 func TestAlertValidate(t *testing.T) {
+	oldScheme := NameValidationScheme
+	NameValidationScheme = LegacyValidation
+	defer func() {
+		NameValidationScheme = oldScheme
+	}()
 	ts := time.Now()
 
 	cases := []struct {

model/metric.go

@@ -28,13 +28,13 @@ import (
 
 var (
 	// NameValidationScheme determines the method of name validation to be used by
-	// all calls to IsValidMetricName() and LabelName IsValid(). Setting UTF-8 mode
-	// in isolation from other components that don't support UTF-8 may result in
-	// bugs or other undefined behavior. This value is intended to be set by
-	// UTF-8-aware binaries as part of their startup. To avoid need for locking,
-	// this value should be set once, ideally in an init(), before multiple
-	// goroutines are started.
-	NameValidationScheme = LegacyValidation
+	// all calls to IsValidMetricName() and LabelName IsValid(). Setting UTF-8
+	// mode in isolation from other components that don't support UTF-8 may result
+	// in bugs or other undefined behavior. This value can be set to
+	// LegacyValidation during startup if a binary is not UTF-8-aware binaries. To
+	// avoid need for locking, this value should be set once, ideally in an
+	// init(), before multiple goroutines are started.
+	NameValidationScheme = UTF8Validation
 
 	// 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