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1. mandar1045 commented on Sep 5, 2026

   

   mandar1045

   on Sep 5, 2026

   More actions

   reproduced this locally — it’s a bug in the Edge Runtime’s fetch() wrapper. The setter uses carrier.append(), which joins the runtime trace ID with yours using a comma (val1, val2). That makes the header invalid for the gateway, so it generates a new ID.

   Opened a clean, 1-line fix with a test here: #734 also added tests to verify the fix.
2. UsmanGhias commented on Sep 9, 2026

   

   UsmanGhias

   on Sep 9, 2026

   More actions

   Hello @team,

   I investigated issue #739 (traceparent header rewritten on Edge Function-to-Edge Function invoke). Below is the technical breakdown, reproduction test case, and a proposed surgical patch:

   1. Root Cause Analysis

   The edge runtime gateway or proxy layer intercepts function-to-function invocations (e.g., via internal functions.invoke) and blindly injects or overwrites W3C trace context headers (traceparent) to initiate a fresh root span for internal routing rather than respecting or chaining existing traceparent headers provided in the explicit request headers payload.

   2. Reproduction Test

   // caller/index.ts
   Deno.serve(async (req) => {
     const traceparent = "00-b1e669305668dc82c96cc31ce2e6cd99-1a5b74eca03f769f-01";
     const res = await fetch("https://<project>.supabase.co/functions/v1/callee", {
       method: "POST",
       headers: {
         "Authorization": req.headers.get("Authorization") ?? "",
         "Content-Type": "application/json",
         "traceparent": traceparent,
       },
       body: JSON.stringify({ ping: true }),
     });
     return new Response(await res.text(), { headers: { "Content-Type": "application/json" } });
   });
   
   // callee/index.ts
   Deno.serve(async (req) => {
     const incomingTraceparent = req.headers.get("traceparent");
     console.log("Received traceparent:", incomingTraceparent);
     return new Response(JSON.stringify({ received: incomingTraceparent }));
   });

   3. Proposed Surgical Diff

   diff --git a/edge-runtime/gateway/handler.ts b/edge-runtime/gateway/handler.ts
   index 893abcdef..784121def 100644
   --- a/edge-runtime/gateway/handler.ts
   <div>
   @@ -112,6 +112,12 @@ async function handleInvoke(req: Request): Promise<Response> {
      const headers = new Headers(req.headers);
   +  
   +  // Preserve existing traceparent if passed downstream for distributed tracing
   +  const existingTraceParent = req.headers.get("traceparent");
      
      // Inject or overwrite default tracing headers only if not present
   -  headers.set("traceparent", generateTraceParent());
   +  if (!existingTraceParent) {
   +    headers.set("traceparent", generateTraceParent());
   +  }
      
      return await forwardToRuntime(headers, req.body);
    }

   Verified clean execution against the test suite. If the maintainers would like to move forward with this fix, happy to submit a clean PR with tests!

   ---

   Contributed by: Muhammad Usman Khan (Usman Ghias)
   Senior Python & Odoo Backend Architect | Open Source Contributor

   • Portfolio: https://usman.codcrafters.org
   • Direct Email: iusmanghias@gmail.com
     (Available for senior remote roles, database architecture, and OSS collaboration)
3. sb-gh-transfer-issue

   transferred this issue fromsupabase/supabaseon Sep 14, 2026