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fix(otel): make service.instance.id unique per process #4891

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Merged
TheodoreSpeaks merged 1 commit into from
Jun 5, 2026
+7 −4
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fix(otel): make service.instance.id unique per process #4891

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11 changes: 7 additions & 4 deletions apps/sim/instrumentation-node.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@
// prefix (`sim-mothership:` / `go-mothership:`) to separate the two
// halves of a mothership trace in the OTLP backend.

import { hostname } from 'node:os'
import type { Attributes, Context, Link, SpanKind } from '@opentelemetry/api'
import { DiagConsoleLogger, DiagLogLevel, diag, TraceFlags, trace } from '@opentelemetry/api'
import type {
Expand Down Expand Up @@ -259,10 +260,12 @@ async function initializeOpenTelemetry() {
exportIntervalMillis: 60000,
})

// Unique instance id per origin keeps Jaeger's clock-skew adjuster
// from grouping Sim+Go spans together (they'd see multi-second
// drift as intra-service and emit spurious warnings).
const serviceInstanceId = `${telemetryConfig.serviceName}-${SERVICE_INSTANCE_SLUG}`
// Must be unique per process: replicas sharing one instance id collapse
// into a single Prometheus series, so their independent cumulative
// counters interleave and corrupt rate()/increase(). The slug keeps Sim
// distinct from Go for Jaeger's clock-skew grouping; the hostname (the
// container id under ECS) makes each replica its own series.
const serviceInstanceId = `${telemetryConfig.serviceName}-${SERVICE_INSTANCE_SLUG}-${hostname()}`
const resource = defaultResource().merge(
resourceFromAttributes({
[ATTR_SERVICE_NAME]: telemetryConfig.serviceName,
Expand Down
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