fix(spanner): disable metrics tracer when built-in metrics are disabled (#8170)

* fix(spanner): disable metrics tracer when built-in metrics are disabled

Ensure MetricsTracerFactory starts disabled and is synchronized with the built-in metrics configuration. This prevents MetricsTracer instances from being created when metrics are disabled via client options, environment, or insecure credentials.

* fix(spanner): honor disabled built-in metrics per client

Track built-in metrics enablement on each Spanner instance and use it to guard metric interceptors and MetricsTracer creation. This prevents clients that explicitly disable built-in metrics from creating or retaining metrics tracers without mutating global MetricsTracerFactory state for other clients.

* 🦉 Updates from OwlBot post-processor

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* fix(spanner): include insecure credentials in metrics guard

Update the per-instance metrics flag to include insecure credentials so metric interceptors and tracers are not created when built-in metrics are disabled for that client. Keep the mock metrics tests using an explicit in-memory metrics override because they intentionally run against insecure test credentials.

* fix(spanner): simplify disabled metrics guard

Default MetricsTracerFactory.enabled to false so tracer creation stays disabled until metrics configuration explicitly enables the singleton factory.

* Revert "fix(spanner): simplify disabled metrics guard"

This reverts commit 8bc203e.

* fix(spanner): sync metrics factory enablement before setup

Move MetricsTracerFactory.enabled assignment outside the metrics setup branch so explicitly disabled or insecure clients update the singleton guard before any request path can create metrics tracers.

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: rahul2393

handwritten/spanner/src/index.ts

@@ -325,6 +325,7 @@ class Spanner extends GrpcService {
   sessionLabels: {[key: string]: string} | null;
   private _universeDomain: string;
   private _isInSecureCredentials: boolean;
+  private _metricsEnabled = false;
   private static _isAFEServerTimingEnabled: boolean | undefined;
   readonly _nthClientId: number;
 
@@ -1626,11 +1627,13 @@ class Spanner extends GrpcService {
   configureMetrics_(disableBuiltInMetrics?: boolean) {
     // Only enable metrics if not explicitly disabled and we are not using
     // insecure credentials.
-    const metricsEnabled =
-      process.env.SPANNER_DISABLE_BUILTIN_METRICS !== 'true' &&
-      !disableBuiltInMetrics &&
-      !this._isInSecureCredentials;
-    if (metricsEnabled) {
+    const metricsExplicitlyDisabled =
+      process.env.SPANNER_DISABLE_BUILTIN_METRICS === 'true' ||
+      !!disableBuiltInMetrics;
+    this._metricsEnabled =
+      !metricsExplicitlyDisabled && !this._isInSecureCredentials;
+    MetricsTracerFactory.enabled = this._metricsEnabled;
+    if (this._metricsEnabled) {
       try {
         this.auth.getProjectId((err, projectId) => {
           if (err || !projectId) {
@@ -1642,7 +1645,6 @@ class Spanner extends GrpcService {
             return;
           }
 
-          MetricsTracerFactory.enabled = metricsEnabled;
           this.projectId_ = projectId;
           const factory = MetricsTracerFactory.getInstance(projectId);
           const periodicReader = new PeriodicExportingMetricReader({
@@ -1728,7 +1730,7 @@ class Spanner extends GrpcService {
       // Attach the x-goog-spanner-request-id to the currently active span.
       attributeXGoogSpannerRequestIdToActiveSpan(config);
       const interceptors: any[] = [];
-      if (MetricsTracerFactory.enabled) {
+      if (this._metricsEnabled) {
         interceptors.push(MetricInterceptor);
       }
       const requestFn = gaxClient[config.method].bind(
@@ -1811,7 +1813,11 @@ class Spanner extends GrpcService {
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   request(config: any, callback?: any): any {
     let metricsTracer: MetricsTracer | null = null;
-    if (config.client === 'SpannerClient' && this.projectId_) {
+    if (
+      this._metricsEnabled &&
+      config.client === 'SpannerClient' &&
+      this.projectId_
+    ) {
       metricsTracer =
         MetricsTracerFactory?.getInstance(this.projectId_)?.createMetricsTracer(
           config.method,
@@ -1875,7 +1881,11 @@ class Spanner extends GrpcService {
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   requestStream(config): any {
     let metricsTracer: MetricsTracer | null = null;
-    if (config.client === 'SpannerClient' && this.projectId_) {
+    if (
+      this._metricsEnabled &&
+      config.client === 'SpannerClient' &&
+      this.projectId_
+    ) {
       metricsTracer =
         MetricsTracerFactory?.getInstance(this.projectId_)?.createMetricsTracer(
           config.method,

handwritten/spanner/test/index.ts

@@ -339,8 +339,7 @@ describe('Spanner', () => {
 
     it('should optionally accept disableBuiltInMetrics', () => {
       const spanner = new Spanner({disableBuiltInMetrics: true});
-      assert.strictEqual(MetricsTracerFactory.enabled, false);
-      MetricsTracerFactory.enabled = true; // Reset for other tests.
+      assert.strictEqual(asAny(spanner)._metricsEnabled, false);
     });
 
     it('should optionally accept directedReadOptions', () => {

handwritten/spanner/test/metrics/metrics.ts

@@ -164,6 +164,7 @@ describe('Test metrics with mock server', () => {
       port,
       sslCreds: grpc.credentials.createInsecure(),
     });
+    (spanner as any)._metricsEnabled = true;
     instance = spanner.instance('instance');
   }