fix(exporter-prometheus): add appendTimestamp option to ExporterConfig

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

@@ -33,13 +33,15 @@ export class PrometheusExporter implements MetricExporter {
     port: 9464,
     endpoint: '/metrics',
     prefix: '',
+    appendTimestamp: true,
   };
 
   private readonly _logger: api.Logger;
   private readonly _port: number;
   private readonly _endpoint: string;
   private readonly _server: Server;
   private readonly _prefix?: string;
+  private readonly _appendTimestamp: boolean;
   private _serializer: PrometheusSerializer;
   private _batcher = new PrometheusLabelsBatcher();
 
@@ -56,8 +58,15 @@ export class PrometheusExporter implements MetricExporter {
     this._logger = config.logger || new NoopLogger();
     this._port = config.port || PrometheusExporter.DEFAULT_OPTIONS.port;
     this._prefix = config.prefix || PrometheusExporter.DEFAULT_OPTIONS.prefix;
+    this._appendTimestamp =
+      typeof config.appendTimestamp === 'boolean'
+        ? config.appendTimestamp
+        : PrometheusExporter.DEFAULT_OPTIONS.appendTimestamp;
     this._server = createServer(this._requestHandler);
-    this._serializer = new PrometheusSerializer(this._prefix);
+    this._serializer = new PrometheusSerializer(
+      this._prefix,
+      this._appendTimestamp
+    );
 
     this._endpoint = (
       config.endpoint || PrometheusExporter.DEFAULT_OPTIONS.endpoint

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

@@ -27,6 +27,12 @@ export interface ExporterConfig {
    * */
   prefix?: string;
 
+  /**
+   * Append timestamp to metrics
+   * @default true
+   */
+  appendTimestamp?: boolean;
+
   /**
    * Endpoint the metrics should be exposed at with preceding slash
    * @default '/metrics'

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

@@ -660,6 +660,36 @@ describe('PrometheusExporter', () => {
         }
       );
     });
+
+    it('should export a metric without timestamp', done => {
+      exporter = new PrometheusExporter(
+        {
+          appendTimestamp: false,
+        },
+        async () => {
+          await meter.collect();
+          exporter!.export(meter.getBatcher().checkPointSet(), () => {
+            http
+              .get('http://localhost:9464/metrics', res => {
+                res.on('data', chunk => {
+                  const body = chunk.toString();
+                  const lines = body.split('\n');
+
+                  assert.deepStrictEqual(lines, [
+                    '# HELP counter description missing',
+                    '# TYPE counter counter',
+                    'counter{key1="labelValue1"} 10',
+                    '',
+                  ]);
+
+                  done();
+                });
+              })
+              .on('error', errorHandler(done));
+          });
+        }
+      );
+    });
   });
 });