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Using both Bun and Express leads to "express is not instrumented" warning (Bun not publishing to http Diagnostic Channel) #17779
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Hello, and thanks for your reproduction!
The OTel-based Node SDKs need the
instrument.tsfile early-imported so it can run before the application starts. In Node, this flag is called--import, but in bun it's--preload.We probably need to update the docs and the log for this.
- moved this from Waiting for: Product Owner to No status in GitHub Issues with 👀 3
on Sep 26, 2025 Hi and thanks for the triage :)
The call to bun already uses
--preload, and I am not quite sure what else to configure to make Bun behave more node-y here.Ah sorry, I missed this. I can have a closer look at this next week :)
But this check if it's wrapped is throwing the warning:
The function is using this OTel function under the hood. Either it's not instrumented correctly or the check is not correct.
Reacted by RudolfSchreier51 remaining items
- moved this from Waiting for: Product Owner to No status in GitHub Issues with 👀 3
on Jan 28, 2026 tl;dr;
Is there a workaround to instrument Express when using it with Bun?There is a semi-functional workaround @s1gr1d and I just found:
If you
requireexpress instead ofimporting it, the express instrumentation can intercept the require call and patch it. But you also need to manually start the server span that would usually be started by thehttpinstrumentation. Once that's started, the express instrumentation can correctly pick up middleware and request handler spans.Here's a simplified example:
import * as SentryBun from "@sentry/bun"; const express = require("express"); const app = express(); app.use((req, res, next) => { const rawUrl = `${req.method} ${req.path}`; return SentryBun.withIsolationScope((isolationScope) => { isolationScope.setTransactionName(rawUrl); return SentryBun.startSpan( { name: rawUrl, attributes: { "sentry.op": "http.server", }, }, () => { next(); } ); }); // Add your routes and middlewares here app.get("/endpoint", (req, res) => { // ... }); app.use(SentryBun.expressErrorHandler()); app.listen(PORT, () => { console.log(`Server running on http://localhost:${PORT}`); });
This is far from optimal of course but it at least should give you basic tracing. In my testing, this also isolated traces for individual requests. Take it with a grain of salt but maybe this helps you for the time being.
I'd imagine you need to
requireother libraries likepgas well to get instrumentation for database spans working.- moved this from Waiting for: Product Owner to No status in GitHub Issues with 👀 3
on Jan 29, 2026 Hey @Lms24, Any updates from the Bun team?
Hi, sadly no updates so far. I saw that @Lms24 also commented on the PR itself already: oven-sh/bun#24375 (comment)
We'll keep you updated - until then we suggest to only comment on this issue to provide useful context on this topic. The state of the PR can be checked in the Bun repository (link above). Thank you 🙏
Reacted by Taj English- moved this from Waiting for: Product Owner to No status in GitHub Issues with 👀 3
on Feb 16, 2026
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Is there an existing issue for this?
How do you use Sentry?
Sentry Saas (sentry.io)
Which SDK are you using?
@sentry/bun
SDK Version
10.15.0
Framework Version
Express 5.1.0
Link to Sentry event
No response
Reproduction Example/SDK Setup
https://github.com/RudolfSchreier/sentry-express-bun-demo
Steps to Reproduce
env SENTRY_DSN=... bun run devExpected Result
The express server starts up with working Sentry integration and no warnings.
Actual Result
The express server starts up, but with a Sentry warning about missing instrumentation:
Additional Context
When using both Bun and Express, it is unclear which SDK to preferably use (@sentry/node or @sentry/bun), but both appear to show this issue.
It is unclear if the warning is correct or erroneous (and Express integration is actually working).
It is unclear to me from the description of #13674 if this the expected result for Express v5.
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+1orme too, to help us triage it.