feat(core): emit faas.instance span attribute for compute instance identity#2989
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🦋 Changeset detectedLatest commit: d1b2338 The changes in this PR will be included in the next version bump. This PR includes changesets to release 16 packages
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📊 Workflow Benchmarkscommit Backend:
📜 Previous results (2)5e0e611Fri, 17 Jul 2026 19:14:49 GMT · run logs
ad3b139Fri, 17 Jul 2026 18:50:22 GMT · run logs
Avg deltas compare against the most recent benchmark run on Metrics — TTFS: time to first step body execution · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (time outside step bodies, client start → last step body exit) · SL: stream latency (first chunk write → visible to the reader) Scenarios — stream: one step that streams chunks back to the client; no hooks, so the run stays in turbo mode · hook + stream: registers a hook before the same streaming step, which exits turbo mode · 1020 steps: 1020 trivial sequential steps; STSO is measured between consecutive steps in the given step ranges 🟢/🔴 mark percentiles within/above target. Targets (p75/p90/p99, ms) — TTFS 200/300/600 · SL 50/60/125 · STSO (1-20) 20/30/60 · STSO (101-120) 30/45/90 · STSO (1001-1020) 40/60/120 TTFS/WO compare client vs deployment clocks and SL compares the step runner’s clock vs the client’s (NTP-synced in CI). WO ends at the last step body exit, the closest observable proxy for the final step-completion request. |
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🧪 E2E Test Results✅ All tests passed Summary
Details by Category✅ ▲ Vercel Production
✅ 💻 Local Development
✅ 📦 Local Production
✅ 🐘 Local Postgres
✅ 🪟 Windows
✅ 📋 Other
✅ vercel-multi-region
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…entity Synthesize a per-warm-instance id (cinst_<ulid>) once at module load and emit it as the OTEL faas.instance attribute on the flow and step route spans. Vercel exposes no native per-instance id under Fluid compute, so this lets traces distinguish which compute instance handled each request. Purely additive telemetry. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Signed-off-by: Alex Langenfeld <alex.langenfeld@vercel.com>
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What
Synthesize a per-instance id (
cinst_<ulid>, minted once at module load) and emit it as the OpenTelemetryfaas.instancespan attribute on the flow and step route spans.Why
Vercel exposes no native per-instance id under Fluid compute (all
AWS_LAMBDA_*env vars are blocked), yet Fluid packs concurrent invocations onto one instance. This attribute tells traces which instance handled each request — the basis for observability that distinguishes steps sharing an instance from those that don't.Scope / risk
Purely additive: a new span attribute behind the existing
span?.setAttributes. No wire-format, schema, or behavior change; no cross-repo dependency; usable now via any OTEL backend.First of a short series — later PRs persist the same id on
step_startedevents to drive the observability UI.🤖 Generated with Claude Code