Graphql requests are not monitoring friendly

[bcaudan]

Intended outcome:

Be able to monitor graphql requests through a third party monitoring library.

Actual outcome:

Third party monitoring library override global fetch to gather data on each request.
Since createHttpLink keep a reference to fetch (code), if global fetch is instrumented after createHttpLink execution then graphql requests can't be instrumented.

How to reproduce the issue:

with a simple fetch override:

const originalFetch = window.fetch;
window.fetch = function () {
  console.log("request instrumented", arguments[0]);
  return originalFetch.apply(this, arguments);
};

if executed before ApolloClient initialization, graphql requests are logged
if executed after ApolloClient initialization, graphql requests are not logged

Versions

master

[danmayer]

This is currently impacting our ability to monitor perf related to Apollo client generated requests. It would be great to come up with a solution that would avoid brittle ordering issues.

[bignimbus]

Hi @bcaudan, thanks for your patience! Would passing the overridden fetch function via the fetch option in HTTP Link per these docs address the issue you're describing?

[bignimbus]

Hi @arminrosu 👋🏻 I see you reacted to the above comment - can you elaborate so that we can better understand your use case and narrow down our options here?

[arminrosu]

@bignimbus gladly, thanks for the interest.

I'm trying to set up Datadog tracing from the client down to our backend services. Datadog does this by setting some headers on GQL requests. They probably do this by wrapping browser requests and appending their headers.

It works if I initialise datadog before the apollo client. But then I started having issues with Apollo Cache. I dropped the topic for now, but that's essentially it.

I haven't tried setting a custom fetch instance, as I don't see it exported.

[bignimbus]

Thanks @arminrosu - looking at the Datadog SDK now.

https://github.com/DataDog/browser-sdk/blob/46c51d01d497128d61532043048fde15d535c331/packages/core/src/browser/fetchObservable.ts#L41-L70

This snippet was interesting to me. It does seem like something that would be resolved by, as you said, initializing the Datadog SDK before Apollo Client.

But then I started having issues with Apollo Cache

That's also interesting and something that might be worth getting more detail on - what issues did you see? Is this a bug in Apollo Client?

[arminrosu]

That's also interesting and something that might be worth getting more detail on - what issues did you see? Is this a bug in Apollo Client?

I'll get back to you once I give this one another shot. I haven't had time to look into it closely yet.

[alessbell]

Hi @arminrosu 👋 Just following up here and was curious if there are any more details you or other participants on this issue can provide to @bignimbus's question above re: downsides to initializing DD SDK before Apollo Client. Thanks!

[arminrosu]

downsides to initializing DD SDK before Apollo Client

@alessbell thanks for checking in. No complaints from doing this. We now have it in production for a few months and everything is working fine.

[phryneas]

I believe this issue should have been solved with #8603 and only occur in Apollo Client versions before v3.4.6.

As a result, I'm going to close this issue.
If it is still occurring in newer versions, please give this a bump so I'll reopen, or open a new issue :)

[github-actions]

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