Undici 6.7.0 changes to request headers breaking Sentry code

[jessezhang91]

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/node

SDK Version

7.105.0

Framework Version

No response

Link to Sentry event

No response

SDK Setup

No response

Steps to Reproduce

I can't figure out how to reproduce it locally but the issue occurs immediately on our staging and production servers for some reason.

I think it's related to undici@6.7.0 changes:
nodejs/undici#2708
nodejs/undici#2879

and this line of code here:

sentry-javascript/packages/node/src/integrations/undici/index.ts

Line 311 in a818271

const headerLines = request.headers.split('\r\n');

Since the headers can now be arrays and iterables, this might not be properly accounting for that when attempting to call .split().

Pinning to undici@6.6.2 does not exhibit this behavior.

Expected Result

No errors

Actual Result

TypeError: request.headers.split is not a function
  File "/var/app/node_modules/@sentry/node/cjs/integrations/undici/index.js", line 266, col 39, in setHeadersOnRequest
    const headerLines = request.headers.split('\r\n');
  File "/var/app/node_modules/@sentry/node/cjs/integrations/undici/index.js", line 177, col 7, in _onRequestCreate
    setHeadersOnRequest(request, sentryTraceHeader, sentryBaggageHeader);
  File "node:diagnostics_channel", line 142, col 9, in Channel.publish
  File "/var/app/node_modules/undici/lib/core/request.js", line 189, col 23, in new Request
    channels.create.publish({ request: this })
  File "/var/app/node_modules/undici/lib/dispatcher/client.js", line 294, col 21, in [dispatch]
    const request = new Request(origin, opts, handler)
  File "/var/app/node_modules/undici/lib/interceptor/redirect-interceptor.js", line 11, col 16, in Intercept
    return dispatch(opts, handler)
  File "/var/app/node_modules/undici/lib/dispatcher/dispatcher-base.js", line 158, col 12, in [Intercepted Dispatch]
    return dispatch(opts, handler)
  File "/var/app/node_modules/undici/lib/dispatcher/dispatcher-base.js", line 179, col 40, in Client.dispatch
    return this[kInterceptedDispatch](opts, handler)
  File "/var/app/node_modules/undici/lib/dispatcher/pool-base.js", line 143, col 28, in [dispatch]
    } else if (!dispatcher.dispatch(opts, handler)) {
  File "/var/app/node_modules/undici/lib/dispatcher/dispatcher-base.js", line 150, col 29, in [Intercepted Dispatch]
    return this[kDispatch](opts, handler)
  File "/var/app/node_modules/undici/lib/dispatcher/dispatcher-base.js", line 179, col 40, in Pool.dispatch
    return this[kInterceptedDispatch](opts, handler)
  File "/var/app/node_modules/undici/lib/dispatcher/agent.js", line 105, col 23, in [dispatch]
    return dispatcher.dispatch(opts, handler)
  File "/var/app/node_modules/undici/lib/interceptor/redirect-interceptor.js", line 11, col 16, in Intercept
    return dispatch(opts, handler)
  File "/var/app/node_modules/undici/lib/dispatcher/dispatcher-base.js", line 158, col 12, in [Intercepted Dispatch]
    return dispatch(opts, handler)
  File "/var/app/node_modules/undici/lib/dispatcher/dispatcher-base.js", line 179, col 40, in Agent.dispatch
    return this[kInterceptedDispatch](opts, handler)
  File "node:internal/deps/undici/undici", line 10929, col 55, in <anonymous>

[AbhiPrasad]

Good catch @jessezhang91 - would you be open to opening a PR to fix this? Otherwise we have to backlog in the time being until someone else can get to it.

[jessezhang91]

I traced down the change to here:
https://github.com/nodejs/undici/pull/2874/files#diff-7d30f7ef62c49f60ef5b01576ca8898402aa790a09c623b13f9e0ea090fba7e6R151

but it seems like the docs haven't been updated to reflect that change:
https://github.com/nodejs/undici/blob/main/docs/docs/api/DiagnosticsChannel.md

so I'm unsure if it's intentional? I'll double check there and apply the updated changes via a PR here when given confirmation.

[jessezhang91]

Here's my rough attempt at a PR: #10938

I don't have an easy way to test my changes beyond editing the node_modules files via patch-package but I did test that in my codebase and confirmed that it did work properly.