feat(nexjs): Sample out low-quality spans on older Next.js versions

packages/core/src/baseclient.ts

@@ -22,6 +22,8 @@ import type {
   SessionAggregates,
   SeverityLevel,
   Span,
+  SpanAttributes,
+  SpanContextData,
   StartSpanOptions,
   TransactionEvent,
   Transport,
@@ -416,6 +418,20 @@ export abstract class BaseClient<O extends ClientOptions> implements Client<O> {
     callback: (feedback: FeedbackEvent, options?: { includeReplay: boolean }) => void,
   ): void;
 
+  /** @inheritdoc */
+  public on(
+    hook: 'afterSampling',
+    callback: (
+      samplingData: {
+        spanAttributes: SpanAttributes;
+        spanName: string;
+        parentSampled?: boolean;
+        parentContext?: SpanContextData;
+      },
+      samplingDecision: { decision: boolean },
+    ) => void,
+  ): void;
+
   /** @inheritdoc */
   public on(
     hook: 'startPageLoadSpan',
@@ -442,6 +458,18 @@ export abstract class BaseClient<O extends ClientOptions> implements Client<O> {
     this._hooks[hook].push(callback);
   }
 
+  /** @inheritdoc */
+  public emit(
+    hook: 'afterSampling',
+    samplingData: {
+      spanAttributes: SpanAttributes;
+      spanName: string;
+      parentSampled?: boolean;
+      parentContext?: SpanContextData;
+    },
+    samplingDecision: { decision: boolean },
+  ): void;
+
   /** @inheritdoc */
   public emit(hook: 'spanStart', span: Span): void;
 

packages/nextjs/src/server/index.ts

@@ -22,6 +22,22 @@ const globalWithInjectedValues = GLOBAL_OBJ as typeof GLOBAL_OBJ & {
   __sentryRewritesTunnelPath__?: string;
 };
 
+// https://github.com/lforst/nextjs-fork/blob/9051bc44d969a6e0ab65a955a2fc0af522a83911/packages/next/src/server/lib/trace/constants.ts#L11
+const NEXTJS_SPAN_NAME_PREFIXES = [
+  'BaseServer',
+  'LoadComponents',
+  'NextServer',
+  'createServer',
+  'startServer',
+  'NextNodeServer',
+  'Render',
+  'AppRender',
+  'Router',
+  'Node',
+  'AppRouteRouteHandlers',
+  'ResolveMetadata',
+];
+
 /**
  * A passthrough error boundary for the server that doesn't depend on any react. Error boundaries don't catch SSR errors
  * so they should simply be a passthrough.
@@ -90,7 +106,7 @@ export function init(options: NodeOptions): void {
     customDefaultIntegrations.push(distDirRewriteFramesIntegration({ distDirName }));
   }
 
-  const opts = {
+  const opts: NodeOptions = {
     environment: process.env.SENTRY_ENVIRONMENT || getVercelEnv(false) || process.env.NODE_ENV,
     defaultIntegrations: customDefaultIntegrations,
     ...options,
@@ -113,6 +129,20 @@ export function init(options: NodeOptions): void {
 
   nodeInit(opts);
 
+  const client = getClient();
+  client?.on('afterSampling', ({ spanAttributes, spanName, parentSampled, parentContext }, samplingDecision) => {
+    // If we encounter a span emitted by Next.js, we do not want to sample it
+    // The reason for this is that the data quality of the spans varies, it is different per version of Next,
+    // and we need to keep our manual instrumentation around for the edge runtime anyhow.
+    // BUT we only do this if we don't have a parent span with a sampling decision yet (or if the parent is remote)
+    if (
+      (spanAttributes['next.span_type'] || NEXTJS_SPAN_NAME_PREFIXES.includes(spanName.split('.')[0])) &&
+      (typeof parentSampled !== 'boolean' || parentContext?.isRemote)
+    ) {
+      samplingDecision.decision = false;
+    }
+  });
+
   addEventProcessor(
     Object.assign(
       (event => {

packages/opentelemetry/src/sampler.ts

@@ -64,15 +64,7 @@ export class SentrySampler implements Sampler {
 
     const parentSampled = parentSpan ? getParentSampled(parentSpan, traceId, spanName) : undefined;
 
-    // If we encounter a span emitted by Next.js, we do not want to sample it
-    // The reason for this is that the data quality of the spans varies, it is different per version of Next,
-    // and we need to keep our manual instrumentation around for the edge runtime anyhow.
-    // BUT we only do this if we don't have a parent span with a sampling decision yet (or if the parent is remote)
-    if (spanAttributes['next.span_type'] && (typeof parentSampled !== 'boolean' || parentContext?.isRemote)) {
-      return { decision: SamplingDecision.NOT_RECORD, traceState: traceState };
-    }
-
-    const [sampled, sampleRate] = sampleSpan(options, {
+    const [samplerDecision, sampleRate] = sampleSpan(options, {
       name: spanName,
       attributes: spanAttributes,
       transactionContext: {
@@ -82,6 +74,20 @@ export class SentrySampler implements Sampler {
       parentSampled,
     });
 
+    const mutableSamplingDecision = { decision: samplerDecision };
+    this._client.emit(
+      'afterSampling',
+      {
+        spanAttributes: spanAttributes,
+        spanName: spanName,
+        parentSampled: parentSampled,
+        parentContext: parentContext,
+      },
+      mutableSamplingDecision,
+    );
+
+    const sampled = mutableSamplingDecision.decision;
+
     const attributes: Attributes = {
       [SEMANTIC_ATTRIBUTE_SENTRY_SAMPLE_RATE]: sampleRate,
     };

packages/types/src/client.ts

@@ -14,7 +14,7 @@ import type { Scope } from './scope';
 import type { SdkMetadata } from './sdkmetadata';
 import type { Session, SessionAggregates } from './session';
 import type { SeverityLevel } from './severity';
-import type { Span } from './span';
+import type { Span, SpanAttributes, SpanContextData } from './span';
 import type { StartSpanOptions } from './startSpanOptions';
 import type { Transport, TransportMakeRequestResponse } from './transport';
 
@@ -178,6 +178,20 @@ export interface Client<O extends ClientOptions = ClientOptions> {
    */
   on(hook: 'spanStart', callback: (span: Span) => void): void;
 
+  /** TODO */
+  on(
+    hook: 'afterSampling',
+    callback: (
+      samplingData: {
+        spanAttributes: SpanAttributes;
+        spanName: string;
+        parentSampled?: boolean;
+        parentContext?: SpanContextData;
+      },
+      samplingDecision: { decision: boolean },
+    ) => void,
+  ): void;
+
   /**
    * Register a callback for whenever a span is ended.
    * Receives the span as argument.
@@ -262,6 +276,18 @@ export interface Client<O extends ClientOptions = ClientOptions> {
   /** Fire a hook whener a span starts. */
   emit(hook: 'spanStart', span: Span): void;
 
+  /** TODO */
+  emit(
+    hook: 'afterSampling',
+    samplingData: {
+      spanAttributes: SpanAttributes;
+      spanName: string;
+      parentSampled?: boolean;
+      parentContext?: SpanContextData;
+    },
+    samplingDecision: { decision: boolean },
+  ): void;
+
   /** Fire a hook whener a span ends. */
   emit(hook: 'spanEnd', span: Span): void;