BatchHTTPLink is not monitoring friendly

[dbasilio]

Issue Description

We're trying to integrate Datadog RUM, which attaches headers to outgoing requests if they match certain patterns. When using HTTPLink, the headers are always correctly attached. When using BatchHTTPLink, the headers are not attached. This was previously not working for HTTPLink but was fixed in #8603, but that same fix was not applied to BatchHTTPLink.

BatchHTTPLink is maintaining a local reference to fetch that monitoring tools cannot inject headers into.

Link to Reproduction

https://github.com/dbasilio/apollo-dd-rum-repro

Reproduction Steps

See the readme in the repro repo

@apollo/client version

3.8.10

[dbasilio]

Related Issues:

• Graphql requests are not monitoring friendly #7130
• HTTP link "fetcher strategy" circumvents common monitoring techniques #7832

[alessbell]

Hi @dbasilio 👋 Thanks for opening this issue - the reproduction and linked issues are helpful :) I'll get this on our team agenda, thanks!

[alessbell]

Quick update, I have a PR open here: #11860

[github-actions]

Do you have any feedback for the maintainers? Please tell us by taking a one-minute survey. Your responses will help us understand Apollo Client usage and allow us to serve you better.

[alessbell]

The fix be included in the next patch release, v3.10.5, which will go out later this week 🚀