feat(metrics): initialise MULTIPLEXED_METRIC_ROUTING_KEY for routing #19096

chargome · 2026-02-04T11:40:40Z

Wouldn't this mean we always just pull the first metric?

yes it would mean we pull the first metric. What I'm thinking now after your comment is that I can add a logic which will check if all metrics and route to same or multiple destinations. Whats your opinion ?

cursor · 2026-02-06T11:18:15Z

New MetricRoutingInfo type not exported from package

Low Severity

The new MetricRoutingInfo interface is defined and used in MetricOptions.routing (as Array<MetricRoutingInfo>), but it's not exported from the package's main entry point (packages/core/src/index.ts). Users can use the routing option but cannot import MetricRoutingInfo to properly type their routing configuration. Other metric types like Metric, MetricType, and SerializedMetric are exported, so this appears to be an oversight.

-Original file line number
+Diff line change
@@ Expand Up / @@ -178,7 +178,7 @@ module.exports = [ @@
         name: 'CDN Bundle',
         path: createCDNPath('bundle.min.js'),
         gzip: true,
-        limit: '28 KB',
+        limit: '28.1 KB',
       },
       {
         name: 'CDN Bundle (incl. Tracing)',
@@ Expand Down @@

-Original file line number
+Diff line change
@@ Expand Up / @@ -57,7 +57,6 @@ export { @@
       getSpanStatusFromHttpCode,
       setHttpStatus,
       makeMultiplexedTransport,
-      MULTIPLEXED_TRANSPORT_EXTRA_KEY,
       moduleMetadataIntegration,
       supabaseIntegration,
       instrumentSupabaseClient,
@@ Expand Down @@

-Original file line number
+Diff line change
@@ -1,5 +1,6 @@
     import type { Scope } from '../scope';
-    import type { Metric, MetricType } from '../types-hoist/metric';
+    import { MULTIPLEXED_METRIC_ROUTING_KEY } from '../transports/multiplexed';
+    import type { Metric, MetricRoutingInfo, MetricType } from '../types-hoist/metric';
     import { _INTERNAL_captureMetric } from './internal';
     /**
@@ Expand All / @@ -20,6 +21,12 @@ export interface MetricOptions { @@
        * The scope to capture the metric with.
        */
       scope?: Scope;
+      /**
+       * The routing information for multiplexed transport.
+       * Each metric can be sent to multiple DSNs.
+       */
+      routing?: Array<MetricRoutingInfo>;
     }
     /**
@@ Expand All / @@ -31,10 +38,10 @@ export interface MetricOptions { @@
      * @param options - Options for capturing the metric.
      */
     function captureMetric(type: MetricType, name: string, value: number, options?: MetricOptions): void {
-      _INTERNAL_captureMetric(
-        { type, name, value, unit: options?.unit, attributes: options?.attributes },
-        { scope: options?.scope },
-      );
+      const attributes = options?.routing
+        ? { ...options.attributes, [MULTIPLEXED_METRIC_ROUTING_KEY]: options.routing }
+        : options?.attributes;
+      _INTERNAL_captureMetric({ type, name, value, unit: options?.unit, attributes }, { scope: options?.scope });
     }
     /**
@@ Expand Down @@

-Original file line number
+Diff line change
@@ Expand Up / @@ -72,10 +72,23 @@ export interface SerializedMetric { @@
       /**
        * Arbitrary structured data that stores information about the metric.
+       * This can contain routing information via the `MULTIPLEXED_METRIC_ROUTING_KEY` key.
        */
       attributes?: Attributes;
     }
     export type SerializedMetricContainer = {
       items: Array<SerializedMetric>;
     };
+    export interface MetricRoutingInfo {
+      /**
+       * The DSN of the Sentry project to send the metric to.
+       */
+      dsn: string;
+      /**
+       * The release of the Sentry project to send the metric to.
+       */
+      release?: string;
+    }

-Original file line number
+Diff line change
@@ Expand Up / @@ -1050,3 +1050,88 @@ describe('_INTERNAL_captureMetric', () => { @@
         });
       });
     });
+    describe('routing attribute preservation', () => {
+      it('preserves routing attributes during serialization', () => {
+        const options = getDefaultTestClientOptions({ dsn: PUBLIC_DSN });
+        const client = new TestClient(options);
+        const scope = new Scope();
+        scope.setClient(client);
+        _INTERNAL_captureMetric(
+          {
+            type: 'counter',
+            name: 'test.metric',
+            value: 1,
+            attributes: {
+              'sentry.routing': [{ dsn: 'https://test.dsn', release: 'v1.0.0' }],
+              normalAttribute: 'value',
+            },
+          },
+          { scope },
+        );
+        const buffer = _INTERNAL_getMetricBuffer(client);
+        expect(buffer).toHaveLength(1);
+        expect(buffer?.[0]?.attributes).toEqual({
+          normalAttribute: {
+            type: 'string',
+            value: 'value',
+          },
+          'sentry.routing': {
+            type: 'string',
+            value: JSON.stringify([{ dsn: 'https://test.dsn', release: 'v1.0.0' }]),
+          },
+        });
+      });
+      it('handles missing attributes during serialization', () => {
+        const options = getDefaultTestClientOptions({ dsn: PUBLIC_DSN });
+        const client = new TestClient(options);
+        const scope = new Scope();
+        scope.setClient(client);
+        _INTERNAL_captureMetric(
+          {
+            type: 'counter',
+            name: 'test.metric',
+            value: 1,
+          },
+          { scope },
+        );
+        const buffer = _INTERNAL_getMetricBuffer(client);
+        expect(buffer).toHaveLength(1);
+        expect(buffer?.[0]?.attributes).toEqual({});
+      });
+      it('preserves all attributes including routing', () => {
+        const options = getDefaultTestClientOptions({ dsn: PUBLIC_DSN, release: 'v1.0.0', environment: 'production' });
+        const client = new TestClient(options);
+        const scope = new Scope();
+        scope.setClient(client);
+        _INTERNAL_captureMetric(
+          {
+            type: 'counter',
+            name: 'test.metric',
+            value: 1,
+            attributes: {
+              'sentry.routing': [{ dsn: 'https://test.dsn' }],
+              feature: 'cart',
+              userId: '12345',
+            },
+          },
+          { scope },
+        );
+        const buffer = _INTERNAL_getMetricBuffer(client);
+        const attrs = buffer?.[0]?.attributes;
+        expect(attrs).toHaveProperty('feature');
+        expect(attrs).toHaveProperty('userId');
+        expect(attrs).toHaveProperty('sentry.release');
+        expect(attrs).toHaveProperty('sentry.environment');
+        expect(attrs).toHaveProperty('sentry.routing');
+      });
+    });

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chargome Feb 4, 2026

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-Original file line number
+Diff line change
@@ -1,7 +1,10 @@
     import { getEnvelopeEndpointWithUrlEncodedAuth } from '../api';
-    import type { Envelope, EnvelopeItemType, EventItem } from '../types-hoist/envelope';
+    import { DEBUG_BUILD } from '../debug-build';
+    import type { Envelope, EnvelopeItemType, EventItem, MetricContainerItem } from '../types-hoist/envelope';
     import type { Event } from '../types-hoist/event';
+    import type { SerializedMetric, SerializedMetricContainer } from '../types-hoist/metric';
     import type { BaseTransportOptions, Transport, TransportMakeRequestResponse } from '../types-hoist/transport';
+    import { debug } from '../utils/debug-logger';
     import { dsnFromString } from '../utils/dsn';
     import { createEnvelope, forEachEnvelopeItem } from '../utils/envelope';
@@ Expand All / @@ -16,6 +19,7 @@ interface MatchParam { @@
        * @param types Defaults to ['event']
        */
       getEvent(types?: EnvelopeItemType[]): Event | undefined;
+      getMetric(): SerializedMetric | undefined;
     }
     type RouteTo = { dsn: string; release: string };
@@ Expand All / @@ -27,6 +31,8 @@ type Matcher = (param: MatchParam) => (string | RouteTo)[]; @@
      */
     export const MULTIPLEXED_TRANSPORT_EXTRA_KEY = 'MULTIPLEXED_TRANSPORT_EXTRA_KEY';
+    export const MULTIPLEXED_METRIC_ROUTING_KEY = 'sentry.routing';
     /**
      * Gets an event from an envelope.
      *
@@ Expand All @@
     }
     /**
-     * Creates a transport that overrides the release on all events.
+     * It iterates over metric containers in an envelope.
+     */
+    function forEachMetricContainer(
+      envelope: Envelope,
+      callback: (container: SerializedMetricContainer, metrics: SerializedMetric[]) => void | boolean,
+    ): void {
+      forEachEnvelopeItem(envelope, (item, type) => {
+        if (type === 'trace_metric') {
+          const container = Array.isArray(item) ? (item[1] as SerializedMetricContainer) : undefined;
+          if (container?.items) {
+            return callback(container, container.items);
+          }
+        }
+      });
+    }
+    /**
+     * Gets a metric from an envelope.
+     *
+     * This is only exported for use in tests and advanced use cases.
+     */
+    export function metricFromEnvelope(envelope: Envelope): SerializedMetric | undefined {
+      let metric: SerializedMetric | undefined;
+      forEachEnvelopeItem(envelope, (item, type) => {
+        if (type === 'trace_metric') {
+          const container = Array.isArray(item) ? (item[1] as SerializedMetricContainer) : undefined;
+          const containerItems = container?.items;
+          if (containerItems) {
+            metric = containerItems[0];
+          }
+        }
+        return !!metric;
+      });
+      return metric;
+    }
+    /**
+     * Applies the release to all metrics in an envelope.
+     */
+    function applyReleaseToMetrics(envelope: Envelope, release: string): void {
+      forEachMetricContainer(envelope, (container, metrics) => {
+        container.items = metrics.map(metric => ({
+          ...metric,
+          attributes: {
+            ...metric.attributes,
+            'sentry.release': { type: 'string', value: release },
+          },
+        }));
+      });
+    }
+    /**
+     * It strips routing attributes from all metrics in an envelope.
+     * This prevents the routing information from being sent to Sentry.
+     */
+    function stripRoutingAttributesFromMetrics(envelope: Envelope): void {
+      let strippedCount = 0;
+      forEachMetricContainer(envelope, (_container, metrics) => {
+        for (const metric of metrics) {
+          if (metric.attributes && MULTIPLEXED_METRIC_ROUTING_KEY in metric.attributes) {
+            DEBUG_BUILD && strippedCount++;
+            // eslint-disable-next-line @typescript-eslint/no-unused-vars
+            const { [MULTIPLEXED_METRIC_ROUTING_KEY]: _routing, ...restAttributes } = metric.attributes;
+            metric.attributes = restAttributes;
+          }
+        }
+      });
+    }
+    /**
+     * Creates a transport that overrides the release on all events and metrics.
      */
     function makeOverrideReleaseTransport<TO extends BaseTransportOptions>(
       createTransport: (options: TO) => Transport,
@@ Expand All @@
             if (event) {
               event.release = release;
             }
+            applyReleaseToMetrics(envelope, release);
             return transport.send(envelope);
           },
         };
@@ Expand All @@
     /** Overrides the DSN in the envelope header  */
     function overrideDsn(envelope: Envelope, dsn: string): Envelope {
+      const clonedItems = envelope[1].map(item => {
+        if (Array.isArray(item) && item[0]?.type === 'trace_metric') {
+          const [header, container] = item as MetricContainerItem;
+          return [
+            { ...header },
+            {
+              ...container,
+              items: container.items ? [...container.items] : [],
+            },
+          ];
+        }
+        return item;
+      });
       return createEnvelope(
         dsn
           ? {
               ...envelope[0],
               dsn,
             }
           : envelope[0],
-        envelope[1],
+        clonedItems as (typeof envelope)[1],
       );
     }
@@ Expand Down Expand Up @@
             ) {
               return event.extra[MULTIPLEXED_TRANSPORT_EXTRA_KEY];
             }
+            const metric = args.getMetric();
+            if (metric?.attributes?.[MULTIPLEXED_METRIC_ROUTING_KEY]) {
+              const routingAttr = metric.attributes[MULTIPLEXED_METRIC_ROUTING_KEY];
+              DEBUG_BUILD && debug.log('[Multiplexed Transport] Found metric routing attribute:', routingAttr);
+              let routingValue: unknown;
+              if (typeof routingAttr === 'object' && routingAttr !== null && 'value' in routingAttr) {
+                routingValue = routingAttr.value;
+                if (typeof routingValue === 'string') {
+                  try {
+                    routingValue = JSON.parse(routingValue);
+                    DEBUG_BUILD && debug.log('[Multiplexed Transport] Parsed routing value:', routingValue);
+                  } catch (e) {
+                    DEBUG_BUILD && debug.warn('[Multiplexed Transport] Failed to parse routing JSON:', e);
+                    return [];
+                  }
+                }
+              } else {
+                routingValue = routingAttr;
+              }
+              if (Array.isArray(routingValue)) {
+                const validRoutes = routingValue.filter(
+                  (route): route is string | RouteTo =>
+                    route !== null &&
+                    route !== undefined &&
+                    (typeof route === 'string' || (typeof route === 'object' && 'dsn' in route)),
+                );
+                DEBUG_BUILD && debug.log('[Multiplexed Transport] Valid routes:', validRoutes);
+                return validRoutes;
+              }
+            }
             return [];
           });
@@ Expand Down Expand Up @@
             return eventFromEnvelope(envelope, eventTypes);
           }
-          const transports = actualMatcher({ envelope, getEvent })
+          function getMetric(): SerializedMetric | undefined {
+            return metricFromEnvelope(envelope);
+          }
+          const transports = actualMatcher({ envelope, getEvent, getMetric })
             .map(result => {
               if (typeof result === 'string') {
                 return getTransport(result, undefined);
@@ Expand All @@
             })
             .filter((t): t is [string, Transport] => !!t);
+          stripRoutingAttributesFromMetrics(envelope);
           // If we have no transports to send to, use the fallback transport
           // Don't override the DSN in the header for the fallback transport. '' is falsy
           const transportsWithFallback: [string, Transport][] = transports.length ? transports : [['', fallbackTransport]];
@@ Expand Down @@

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New MetricRoutingInfo type not exported from package

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New `MetricRoutingInfo` type not exported from package