#521: add federation to core:

[t1]

• move federation api into smallrye-graphql-api
• add config to enable federation
• add dependency on com.apollographql.federation:federation-graphql-java-support
• transform federation schema
• remove old federation module

• [x] implement Bootstrap#fetchEntities and Bootstrap#fetchEntityType
• [ ] add tests
• [ ] properly resolve the class name
• [ ] update README.

[johgoe]

@t1 In our project we got a working quarkus server with federation, with some technical tricks like working with a 2nd jandex index and manipulation of the schema in the federation gateway itself. Because of that we find some cases that hat not been working before in Smallrye Federation. I pushed this changes to
https://github.com/smallrye/smallrye-graphql/pull/1135 Maybe it can support you for rewriting.

[t1]

@phillip-kruger & @johgoe : I think the core federation functionality should be working. I have some trouble to get my tests with the ApolloGateway to work properly. It seem that it doesn't recognise the @key(fields : ["id"]) directive, but AFAIU this should be legal. IIRC I had to work around this in the former, hand-made solution. Could you help me double-check?

[t1]

It works after updating Apollo to the latest version!!! So it was a bug.

I shared my demo project: https://github.com/t1/smallrye-graphql-federation-demo

I'll continue writing tests now.

Comments welcome!!!!!!!1111

[phillip-kruger]

Thanks @t1. I'll have a look a.s.a.p

[t1]

Is the documentation sufficient?

[robp94]

Looks nice. Does it support mutiny return types? Would this already work with quarkus? Then we could test it with our services and see if we find anything.

[t1]

Does it support mutiny return types?

It probably should, but I haven't tried.

Would this already work with quarkus?

The quarkus tests fail with compile errors that I don't recognise immediately.

[t1]

I think this is complete now and could be merged.

[phillip-kruger]

Hi @t1 - Thanks for this. I'll have a look as soon as I have a gap

[t1]

@jmartisk: it looks like @phillip-kruger is extremely busy with other things right now. maybe you can give some feedback?

[phillip-kruger]

I'll look at this soon. This will need a thorough review and we need to see if this will work in Quarkus

[jmartisk]

This could also use writing some Quarkus-side integration test coverage as part of doing the review (well, if possible - because running a real integration test seems to require a gateway and at least two Quarkus instances, which makes it very difficult) If you prefer I can get to it, but I'm quite unfamiliar with Federation so it will take me quite some time

[t1]

You're right, writing a real integration test would mean running a node app. But there's already a simplified integration test in the tck package, which only checks the result of a single federated request. This, and the Federation specific directives, should be good enough for now. And maybe we will get back to Feder soon, so we could add a full integration test and still stay 100% Java.

[t1]

hmmm... the build had a timeout when downloading some dependency. How can I restart the build? This used to be easy!

[jmartisk]

I'd suggest rebasing, as there is a conflict anyway ;) and pushing again

[phillip-kruger]

@jmartisk - I am merging here. Can you help with creating a new 1.9.x branch and backport (non-Jakarata) to there ? Then I cal look at the jandex in that branch and once we are happy we can get this into Quarkus. Le me know

[phillip-kruger]

@t1 Thanks for this massive contribution !

[jmartisk]

I'll create a 1.9.x branch with this that will target Quarkus 2.15, which is due some time in December or January, so we will have enough time to polish it. At minimum, I believe we should make the new dependency (federation-graphql-java-support) optional so it doesn't have to be included with every application even if it doesn't use Federation.