Using both Bun and Express leads to "express is not instrumented" warning

[RudolfSchreier]

Is there an existing issue for this?

• I have checked for existing issues https://github.com/getsentry/sentry-javascript/issues
• I have reviewed the documentation https://docs.sentry.io/
• I am using the latest SDK release https://github.com/getsentry/sentry-javascript/releases

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

1. Get a working SENTRY_DSN for some project
2. start the demo using env SENTRY_DSN=... bun run dev

Expected 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:

[Sentry] express is not instrumented. Please make sure to initialize Sentry in a separate file that you --import when running node, see: https://docs.sentry.io/platforms/javascript/guides/express/install/esm/.

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.

_{Tip: React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it.}

[linear]

JS-987 Using both Bun and Express leads to "express is not instrumented" warning

[s1gr1d]

Hello, and thanks for your reproduction!

The OTel-based Node SDKs need the instrument.ts file 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.

[RudolfSchreier]

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.

[s1gr1d]

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:

sentry-javascript/packages/node/src/integrations/tracing/express.ts

Line 185 in 5310112

ensureIsWrapped(app.use, 'express');

The function is using this OTel function under the hood. Either it's not instrumented correctly or the check is not correct.