feat(monitoring-exporter): add disableCreateMetricDescriptors option to skip checking for metric descriptor existence

packages/opentelemetry-cloud-monitoring-exporter/src/external-types.ts

@@ -47,6 +47,14 @@ export interface ExporterOptions {
    * monitoring.googleapis.com:443.
    */
   apiEndpoint?: string;
+  /**
+   * Disable calling CreateMetricDescriptor before sending time series to Cloud Monitoring.
+   * Metric descriptors will be
+   * {@link https://cloud.google.com/monitoring/custom-metrics/creating-metrics#auto-creation | auto-created}
+   * if needed, but may be missing descriptions. This can prevent hitting a rate limit in
+   * Cloud Monitoring when a large number of clients are all started up at the same time.
+   */
+  disableCreateMetricDescriptors?: boolean;
 }
 
 export interface Credentials {

packages/opentelemetry-cloud-monitoring-exporter/src/monitoring.ts

@@ -60,6 +60,7 @@ export class MetricExporter implements PushMetricExporter {
   private _projectId: string | void | Promise<string | void>;
   private readonly _metricPrefix: string;
   private readonly _auth: GoogleAuth;
+  private readonly _disableCreateMetricDescriptors: boolean;
 
   static readonly DEFAULT_METRIC_PREFIX: string = 'workload.googleapis.com';
 
@@ -73,6 +74,8 @@ export class MetricExporter implements PushMetricExporter {
 
   constructor(options: ExporterOptions = {}) {
     this._metricPrefix = options.prefix ?? MetricExporter.DEFAULT_METRIC_PREFIX;
+    this._disableCreateMetricDescriptors =
+      !!options.disableCreateMetricDescriptors;
 
     this._auth = new GoogleAuth({
       credentials: options.credentials,
@@ -145,7 +148,9 @@ export class MetricExporter implements PushMetricExporter {
     const timeSeries: TimeSeries[] = [];
     for (const scopeMetric of resourceMetrics.scopeMetrics) {
       for (const metric of scopeMetric.metrics) {
-        const isRegistered = await this._registerMetricDescriptor(metric);
+        const isRegistered =
+          this._disableCreateMetricDescriptors ||
+          (await this._registerMetricDescriptor(metric));
         if (isRegistered) {
           timeSeries.push(
             ...createTimeSeries(metric, resource, this._metricPrefix)

packages/opentelemetry-cloud-monitoring-exporter/test/monitoring.test.ts

@@ -279,19 +279,68 @@ describe('MetricExporter', () => {
           });
         });
 
+        assert.strictEqual(metricDescriptorsGet.callCount, 1);
         assert.strictEqual(metricDescriptorCreate.callCount, 1);
         assert.strictEqual(timeSeries.callCount, 1);
         assert.deepStrictEqual(result.code, ExportResultCode.SUCCESS);
 
         // Second time around, MetricDescriptorCreate.create() should be skipped
         metricDescriptorCreate.resetHistory();
+        metricDescriptorsGet.resetHistory();
         timeSeries.resetHistory();
         result = await new Promise<ExportResult>(resolve => {
           exporter.export(resourceMetrics, result => {
             resolve(result);
           });
         });
 
+        assert.strictEqual(metricDescriptorsGet.callCount, 0);
+        assert.strictEqual(metricDescriptorCreate.callCount, 0);
+        assert.strictEqual(timeSeries.callCount, 1);
+        assert.deepStrictEqual(result.code, ExportResultCode.SUCCESS);
+      });
+
+      it('should skip fetching the MetricDescriptors when disableCreateMetricDescriptors is set', async () => {
+        const exporterSkipDescriptorCreate = new MetricExporter({
+          disableCreateMetricDescriptors: true,
+        });
+        sinon.replace(
+          exporterSkipDescriptorCreate['_monitoring'].projects
+            .metricDescriptors,
+          'create',
+          metricDescriptorCreate as sinon.SinonSpy
+        );
+        sinon.replace(
+          exporterSkipDescriptorCreate['_monitoring'].projects
+            .metricDescriptors,
+          'get',
+          metricDescriptorsGet as sinon.SinonSpy
+        );
+        sinon.replace(
+          exporterSkipDescriptorCreate['_monitoring'].projects.timeSeries,
+          'create',
+          timeSeries as any
+        );
+        sinon.replace(
+          exporterSkipDescriptorCreate['_auth'],
+          'getClient',
+          () => {
+            if (getClientShouldFail) {
+              throw new Error('fail');
+            }
+            return {} as any;
+          }
+        );
+
+        resourceMetrics = await generateMetricsData();
+
+        const result = await new Promise<ExportResult>(resolve => {
+          exporterSkipDescriptorCreate.export(resourceMetrics, result => {
+            resolve(result);
+          });
+        });
+
+        assert.strictEqual(metricDescriptorsGet.callCount, 0);
         assert.strictEqual(metricDescriptorCreate.callCount, 0);
         assert.strictEqual(timeSeries.callCount, 1);
         assert.deepStrictEqual(result.code, ExportResultCode.SUCCESS);