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Vercel can stream your app’s traces - including AI SDK telemetry - to Glassray via a Trace Drain: Vercel POSTs standard OTLP/JSON to Glassray’s ingest endpoint. Setup is copying three values into the Vercel dashboard.
Trace Drains require a Vercel Pro or Enterprise plan. On Hobby, use the exporter env-var fallback below - same endpoint, configured in your project instead of a drain.

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Step 1 - Get your Glassray ingest details

In Glassray: Settings → Sources → Add source → Vercel. Glassray creates the source, mints a write-scoped ingest key (shown once), and displays the two values you’ll paste into Vercel:
  • the endpoint URL (https://app.glassray.ai/api/public/otel/v1/traces)
  • one custom header line (Authorization: Bearer glsk_…)
Create one Glassray source per Vercel project and scope the drain to that project - the ingest key routes every trace it receives into the source’s Glassray project, so a 1:1 mapping keeps workspaces clean.

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Step 2 - Add a Trace Drain in Vercel

In the Vercel dashboard: Team Settings → Drains → Add Drain.
  1. Choose data to drain: Traces
  2. Configure the drain: name it, pick the Vercel project(s) to send
  3. Configure the destination - stay on the Custom Endpoint tab:
    • URL → paste the Glassray endpoint
    • Encoding → JSON (not Protobuf - Glassray’s endpoint is JSON-only and will reject protobuf with a 415)
    • Custom Headers → toggle on, paste the Authorization: Bearer glsk_… line
    • Signature Verification Secret → leave as generated (not used by Glassray; auth rides the header)
    • Click Test - expect success - then Create Drain
Drains bill per GB. Add a path-prefix sampling rule on the drain (e.g. only /api/chat) so framework and static-asset traffic never leaves Vercel - Glassray only needs the routes that run your AI code.

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Step 3 - Emit AI telemetry and verify

Register OpenTelemetry in your app’s instrumentation.ts:
instrumentation.ts
And enable telemetry on your AI SDK calls:
Deploy, trigger one AI request, and watch the source flip to Connected on the Sources page.
Keep AI routes on the Node runtime. Spans created in the Edge runtime never reach Trace Drains - if your AI route sets export const runtime = "edge", its AI spans will be missing. Remove the override (Node is the default) or move the AI calls to a Node route.

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What Glassray captures

A drained trace mixes Vercel’s own spans (edge routing, function invocation, Next.js framework steps) with your app’s AI spans. Glassray:
  • reads the gen_ai.* semantic conventions and the AI SDK’s ai.* telemetry attributes - model, tokens (including cache read/write), messages, tool calls, finish reason;
  • computes cost from tokens × model price when the span doesn’t carry an explicit cost;
  • merges a trace that arrives across several drain POSTs (normal for Vercel) into one complete trace;
  • names the trace from your app’s request handler (e.g. POST /api/chat/route), not Vercel’s infra spans;
  • tags each trace with its Vercel project, deployment, repo, and commit SHA from the drain’s resource attributes.
Filter rules for a Vercel source should use “any span” (descendant) scope - the trace root is Vercel’s own infra span, so root-scoped rules are unreliable; Vercel-side path sampling plus a descendant keep-rule is the recommended combination.

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Hobby plan fallback

Without a drain, point the AI SDK / OTel exporter at the same endpoint via project env vars (Project → Settings → Environment Variables):
See Send traces via OpenTelemetry for the full exporter reference.

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Troubleshooting

  • Test button fails - check the URL has no trailing spaces, Encoding is JSON, and the header line is exactly Authorization: Bearer glsk_… (one line, no quotes).
  • Drain created but no traces - confirm the drain includes your Vercel project, telemetry is registered (instrumentation.ts), and the AI route runs on the Node runtime.
  • Traces arrive but no AI spans - enable experimental_telemetry on your AI SDK calls (or add @ai-sdk/otel); plain HTTP spans alone mean the AI instrumentation isn’t emitting.
  • Using Sentry v8+? Its SDK takes over OTel setup by default and can swallow spans - set skipOpenTelemetrySetup: true in Sentry.init and keep @vercel/otel as the registration point.
  • Very large prompts - Vercel truncates span attributes over ~1 MB (the trace shows a truncated tag in Glassray) and drops spans over the cap entirely.