fix(prometheus-sanitization): replace repeated _ with a single _ (#3470)

* fix(prometheus-sanitization): fix multiple underscores

* fix(prometheus-sanitization): updated test to check for multiple underscores as well

* fix(prometheus-sanitization): updated CHANGELOG.md

Co-authored-by: Daniel Dyla <[email protected]>

Author: samimusallam

experimental/CHANGELOG.md

@@ -18,6 +18,7 @@ All notable changes to experimental packages in this project will be documented
 * fix(instrumentation-grpc): always set grpc semcov status code attribute with numeric value [#3076](https://github.com/open-telemetry/opentelemetry-js/pull/3076) @blumamir
 * fix(instrumentation): only call `onRequire` for full matches on core modules with sub-paths [#3451](https://github.com/open-telemetry/opentelemetry-js/pull/3451) @mhassan1
 * fix(instrumentation): add back support for absolute paths via `require-in-the-middle` [#3457](https://github.com/open-telemetry/opentelemetry-js/pull/3457) @mhassan1
+* fix(prometheus-sanitization): replace repeated `_` with a single `_` [3470](https://github.com/open-telemetry/opentelemetry-js/pull/3470) @samimusallam
 
 ### :books: (Refine Doc)
 

experimental/packages/opentelemetry-exporter-prometheus/src/PrometheusSerializer.ts

@@ -56,6 +56,7 @@ function escapeAttributeValue(str: MetricAttributeValue = '') {
 }
 
 const invalidCharacterRegex = /[^a-z0-9_]/gi;
+const multipleUnderscoreRegex = /_{2,}/g;
 
 /**
  * Ensures metric names are valid Prometheus metric names by removing
@@ -76,7 +77,10 @@ const invalidCharacterRegex = /[^a-z0-9_]/gi;
  * @param name name to be sanitized
  */
 function sanitizePrometheusMetricName(name: string): string {
-  return name.replace(invalidCharacterRegex, '_'); // replace all invalid characters with '_'
+  // replace all invalid characters with '_'
+  return name
+    .replace(invalidCharacterRegex, '_')
+    .replace(multipleUnderscoreRegex, '_');
 }
 
 /**

experimental/packages/opentelemetry-exporter-prometheus/test/PrometheusExporter.test.ts

@@ -374,7 +374,7 @@ describe('PrometheusExporter', () => {
     });
 
     it('should sanitize names', async () => {
-      const counter = meter.createCounter('counter.bad-name');
+      const counter = meter.createCounter('counter..bad-name');
 
       counter.add(10, { key1: 'attributeValue1' });