Fix unit and name regexes (#2796)

* Fix unit and name regexes

Fixes #2793

* Add changelog entry

Author: ocelotl

CHANGELOG.md

@@ -7,8 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased](https://github.com/open-telemetry/opentelemetry-python/compare/v1.12.0rc1-0.31b0...HEAD)
 
+- Fix instrument name and unit regexes
+  ([#2796](https://github.com/open-telemetry/opentelemetry-python/pull/2796))
 - Add optional sessions parameter to all Exporters leveraging requests.Session
-([#2783](https://github.com/open-telemetry/opentelemetry-python/pull/2783))
+  ([#2783](https://github.com/open-telemetry/opentelemetry-python/pull/2783))
 - Add min/max fields to Histogram
   ([#2759](https://github.com/open-telemetry/opentelemetry-python/pull/2759))
 - `opentelemetry-exporter-otlp-proto-http` Add support for OTLP/HTTP log exporter

opentelemetry-api/src/opentelemetry/metrics/_internal/instrument.py

@@ -18,7 +18,6 @@
 from abc import ABC, abstractmethod
 from dataclasses import dataclass
 from logging import getLogger
-from re import ASCII
 from re import compile as re_compile
 from typing import (
     Callable,
@@ -39,8 +38,8 @@
 
 _logger = getLogger(__name__)
 
-_name_regex = re_compile(r"[a-zA-Z][-.\w]{0,62}", ASCII)
-_unit_regex = re_compile(r"\w{0,63}", ASCII)
+_name_regex = re_compile(r"[a-zA-Z][-_.a-zA-Z0-9]{0,62}")
+_unit_regex = re_compile(r"[\x00-\x7F]{0,63}")
 
 
 @dataclass(frozen=True)

opentelemetry-api/tests/metrics/test_instruments.py

@@ -571,6 +571,7 @@ def test_name_regex(self):
         self.assertTrue(instrument._check_name_and_unit("a.", "unit")[0])
         self.assertTrue(instrument._check_name_and_unit("a-", "unit")[0])
         self.assertTrue(instrument._check_name_and_unit("a_", "unit")[0])
+
         self.assertFalse(instrument._check_name_and_unit("a" * 64, "unit")[0])
         self.assertFalse(instrument._check_name_and_unit("Ñ", "unit")[0])
         self.assertFalse(instrument._check_name_and_unit("_a", "unit")[0])
@@ -582,5 +583,7 @@ def test_unit_regex(self):
         instrument = ChildInstrument("name")
 
         self.assertTrue(instrument._check_name_and_unit("name", "a" * 63)[1])
+        self.assertTrue(instrument._check_name_and_unit("name", "{a}")[1])
+
         self.assertFalse(instrument._check_name_and_unit("name", "a" * 64)[1])
         self.assertFalse(instrument._check_name_and_unit("name", "Ñ")[1])