Allow '/' character in instrument names (#4501)

* Allow '/' character in instrument names

* Add changelog

* Update CHANGELOG.md

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

---------

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

CHANGELOG.md

@@ -8,6 +8,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ## [Unreleased]
 
+### Changed
+
+- Allow '/' characters in metric instrument names. (#4501)
+
 ## [1.18.0/0.41.0/0.0.6] 2023-09-12
 
 This release drops the compatibility guarantee of [Go 1.19].

sdk/metric/meter.go

@@ -28,7 +28,7 @@ import (
 
 var (
 	// ErrInstrumentName indicates the created instrument has an invalid name.
-	// Valid names must consist of 255 or fewer characters including alphanumeric, _, ., -, and start with a letter.
+	// Valid names must consist of 255 or fewer characters including alphanumeric, _, ., -, / and start with a letter.
 	ErrInstrumentName = errors.New("invalid instrument name")
 )
 
@@ -262,8 +262,8 @@ func validateInstrumentName(name string) error {
 		return nil
 	}
 	for _, c := range name[1:] {
-		if !isAlphanumeric(c) && c != '_' && c != '.' && c != '-' {
-			return fmt.Errorf("%w: %s: must only contain [A-Za-z0-9_.-]", ErrInstrumentName, name)
+		if !isAlphanumeric(c) && c != '_' && c != '.' && c != '-' && c != '/' {
+			return fmt.Errorf("%w: %s: must only contain [A-Za-z0-9_.-/]", ErrInstrumentName, name)
 		}
 	}
 	return nil

sdk/metric/meter_test.go

@@ -775,9 +775,12 @@ func TestValidateInstrumentName(t *testing.T) {
 		{
 			name: "nam.",
 		},
+		{
+			name: "nam/e",
+		},
 		{
 			name:    "name!",
-			wantErr: fmt.Errorf("%w: name!: must only contain [A-Za-z0-9_.-]", ErrInstrumentName),
+			wantErr: fmt.Errorf("%w: name!: must only contain [A-Za-z0-9_.-/]", ErrInstrumentName),
 		},
 		{
 			name:    longName,