feat(exporter-prometheus): add option to add resource attributes as m…

…etric attributes

experimental/CHANGELOG.md

@@ -16,6 +16,9 @@ All notable changes to experimental packages in this project will be documented
 
 ### :rocket: (Enhancement)
 
+* feat(exporter-prometheus): add additional attributes option [#5317](/~https://github.com/open-telemetry/opentelemetry-js/pull/5317) @marius-a-mueller
+  * Add `withResourceConstantLabels` option to `ExporterConfig`. It can be used to define a regex pattern to choose which resource attributes will be used as static labels on the metrics. The default is to not set any static labels.
+
 ### :bug: (Bug Fix)
 
 * fix(exporter-metrics-otlp-http): browser OTLPMetricExporter was not passing config to OTLPMetricExporterBase super class [#5331](/~https://github.com/open-telemetry/opentelemetry-js/pull/5331) @trentm

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

@@ -34,6 +34,7 @@ export class PrometheusExporter extends MetricReader {
     endpoint: '/metrics',
     prefix: '',
     appendTimestamp: false,
+    withResourceConstantLabels: undefined,
   };
 
   private readonly _host?: string;
@@ -43,6 +44,7 @@ export class PrometheusExporter extends MetricReader {
   private readonly _server: Server;
   private readonly _prefix?: string;
   private readonly _appendTimestamp: boolean;
+  private readonly _withResourceConstantLabels?: string | RegExp;
   private _serializer: PrometheusSerializer;
   private _startServerPromise: Promise<void> | undefined;
 
@@ -82,11 +84,15 @@ export class PrometheusExporter extends MetricReader {
       typeof config.appendTimestamp === 'boolean'
         ? config.appendTimestamp
         : PrometheusExporter.DEFAULT_OPTIONS.appendTimestamp;
+    this._withResourceConstantLabels =
+      config.withResourceConstantLabels ||
+      PrometheusExporter.DEFAULT_OPTIONS.withResourceConstantLabels;
     // unref to prevent prometheus exporter from holding the process open on exit
     this._server = createServer(this._requestHandler).unref();
     this._serializer = new PrometheusSerializer(
       this._prefix,
-      this._appendTimestamp
+      this._appendTimestamp,
+      this._withResourceConstantLabels
     );
 
     this._baseUrl = `http://${this._host}:${this._port}/`;

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

@@ -174,17 +174,29 @@ const NO_REGISTERED_METRICS = '# no registered metrics';
 export class PrometheusSerializer {
   private _prefix: string | undefined;
   private _appendTimestamp: boolean;
+  private _additionalAttributes: Attributes | undefined;
+  private _withResourceConstantLabels: string | RegExp | undefined;
 
-  constructor(prefix?: string, appendTimestamp = false) {
+  constructor(
+    prefix?: string,
+    appendTimestamp = false,
+    withResourceConstantLabels?: string | RegExp
+  ) {
     if (prefix) {
       this._prefix = prefix + '_';
     }
     this._appendTimestamp = appendTimestamp;
+    this._withResourceConstantLabels = withResourceConstantLabels;
   }
 
   serialize(resourceMetrics: ResourceMetrics): string {
     let str = '';
 
+    this._additionalAttributes = this._filterResourceConstantLabels(
+      resourceMetrics.resource.attributes,
+      this._withResourceConstantLabels
+    );
+
     for (const scopeMetrics of resourceMetrics.scopeMetrics) {
       str += this._serializeScopeMetrics(scopeMetrics);
     }
@@ -196,6 +208,23 @@ export class PrometheusSerializer {
     return this._serializeResource(resourceMetrics.resource) + str;
   }
 
+  private _filterResourceConstantLabels(
+    attributes: Attributes,
+    pattern: string | RegExp | undefined
+  ) {
+    if (pattern) {
+      const filteredAttributes: Attributes = {};
+      for (const [key, value] of Object.entries(attributes)) {
+        const sanitizedAttributeName = sanitizePrometheusMetricName(key);
+        if (sanitizedAttributeName.match(pattern)) {
+          filteredAttributes[sanitizedAttributeName] = value;
+        }
+      }
+      return filteredAttributes;
+    }
+    return;
+  }
+
   private _serializeScopeMetrics(scopeMetrics: ScopeMetrics) {
     let str = '';
     for (const metric of scopeMetrics.metrics) {
@@ -263,7 +292,7 @@ export class PrometheusSerializer {
       attributes,
       value,
       this._appendTimestamp ? timestamp : undefined,
-      undefined
+      this._additionalAttributes
     );
     return results;
   }
@@ -288,7 +317,7 @@ export class PrometheusSerializer {
           attributes,
           value,
           this._appendTimestamp ? timestamp : undefined,
-          undefined
+          this._additionalAttributes
         );
     }
 
@@ -315,12 +344,12 @@ export class PrometheusSerializer {
         attributes,
         cumulativeSum,
         this._appendTimestamp ? timestamp : undefined,
-        {
+        Object.assign({}, this._additionalAttributes ?? {}, {
           le:
             upperBound === undefined || upperBound === Infinity
               ? '+Inf'
               : String(upperBound),
-        }
+        })
       );
     }
 

experimental/packages/opentelemetry-exporter-prometheus/src/export/types.ts

@@ -66,4 +66,12 @@ export interface ExporterConfig {
    * @experimental
    */
   metricProducers?: MetricProducer[];
+
+  /**
+   * Regex pattern for defining which resource attributes will be applied
+   * as constant labels to the metrics.
+   * e.g. 'telemetry_.+' for all attributes starting with 'telemetry'.
+   * @default undefined (no resource attributes are applied)
+   */
+  withResourceConstantLabels?: string | RegExp;
 }

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

@@ -553,6 +553,40 @@ describe('PrometheusExporter', () => {
         '',
       ]);
     });
+
+    it('should export a metric with all resource attributes', async () => {
+      exporter = new PrometheusExporter({
+        withResourceConstantLabels: '.*',
+      });
+      setup(exporter);
+      const body = await request('http://localhost:9464/metrics');
+      const lines = body.split('\n');
+
+      assert.deepStrictEqual(lines, [
+        ...serializedDefaultResourceLines,
+        '# HELP counter_total description missing',
+        '# TYPE counter_total counter',
+        `counter_total{key1="attributeValue1",service_name="${serviceName}",telemetry_sdk_language="${sdkLanguage}",telemetry_sdk_name="${sdkName}",telemetry_sdk_version="${sdkVersion}"} 10`,
+        '',
+      ]);
+    });
+
+    it('should export a metric with two resource attributes', async () => {
+      exporter = new PrometheusExporter({
+        withResourceConstantLabels: 'telemetry_sdk_language|telemetry_sdk_name',
+      });
+      setup(exporter);
+      const body = await request('http://localhost:9464/metrics');
+      const lines = body.split('\n');
+
+      assert.deepStrictEqual(lines, [
+        ...serializedDefaultResourceLines,
+        '# HELP counter_total description missing',
+        '# TYPE counter_total counter',
+        `counter_total{key1="attributeValue1",telemetry_sdk_language="${sdkLanguage}",telemetry_sdk_name="${sdkName}"} 10`,
+        '',
+      ]);
+    });
   });
 });