[AS-252] gateway: normalize root operation types in reporting

[glasser]

The federation spec allows your backends to use any name for their root
types (not just the standard Query/Mutation/Subscription) but the composed
schema will always use the standard names.

Both Apollo-maintained implementations of federated trace
reporting (apollo-engine-reporting and federation-jvm) include the backend's
potentially nonstandard name in the federated traces sent to the gateway. Then
the gateway continues to use those names in the traces it sends to AGM.

For example, one of AGM's own implementing services uses QueryRoot, so traces
produced by the gateway in front of it have QueryRoot on the traces despite
that type not actually being part of the composed schema.

The effect is that field stats (on the schema explorer) for all root fields are
empty!

Because normalizing root operation names is part of the federation spec, it
makes sense to keep the implementing services simple and fix this just once in
the gateway.

[glasser]

I'd appreciate a review now but I definitely will want to add tests, CHANGELOG, etc before merging!

Requesting review from @jsegaran for his understanding of reporting and @trevor-scheer for his understanding of federation.

[glasser]

@trevor-scheer the second commit makes this feature be tested, but makes some other tests fail. Any chance you can look into this (with me perhaps)? I would think the other tests should pass.

[glasser]

Oh it's because the tests call composeServices instead of its wrapper composeAndValidate, and only composeAndValidate calls normalizeTypedefs. @trevor-scheer what do you think? I changed it to have the tests call normalizeTypedefs (which I think requires exporting normalizeTypedefs from @apollo/federation purely for use in gateway tests), but maybe these tests (executeQueryPlan.test.ts and buildQueryPlan.test.ts) could just call composeAndValidate instead?

[trevor-scheer]

This LGTM, pending a changelog entry. Note, the gateway has its own changelog separate from the top level AS repo changelog.

As far as having to add normalizeTypeDefs within tests go, I think it will make sense to stop exposing composeServices to the public API and use composeAndValidate everywhere we can in tests. This in turn will remove the need to use normalizeTypeDefs in these tests. For now I don't think this PR needs to be concerned with that change.

In the same vein, I'm happy to see us testing the normalization code path within one of our common test fixtures!

[glasser]

Thanks @trevor-scheer — how does this changelog look?

[trevor-scheer]

@glasser perfect, thank you! Per your request I'll hold off on merging this until @jsegaran gets a chance to review as well.

[glasser]

Sure, though if you'd like to cut a pre-release off this branch I could test it in our staging infrastructure even pending @jsegaran 's review.

[jsegaran]

This looks good to me.