meter (#1274)

Author: lzchen

opentelemetry-sdk/CHANGELOG.md

@@ -29,6 +29,9 @@
 
 - Remove context from Metric force_flush [#1245](https://github.com/open-telemetry/opentelemetry-rust/pull/1245)
 
+### Fixed
+
+- Fix metric instrument name validation to include `_` #1030
 
 ## v0.20.0
 

opentelemetry-sdk/src/metrics/meter.rs

@@ -25,7 +25,7 @@ use crate::metrics::{
 const INSTRUMENT_NAME_MAX_LENGTH: usize = 255;
 // maximum length of instrument unit name
 const INSTRUMENT_UNIT_NAME_MAX_LENGTH: usize = 63;
-const INSTRUMENT_NAME_ALLOWED_NON_ALPHANUMERIC_CHARS: [char; 4] = ['-', '.', '-', '/'];
+const INSTRUMENT_NAME_ALLOWED_NON_ALPHANUMERIC_CHARS: [char; 4] = ['_', '.', '-', '/'];
 
 // instrument validation error strings
 const INSTRUMENT_NAME_EMPTY: &str = "instrument name must be non-empty";