Query "query getService { _service { sdl } }" ignores the directive @interfaceObject

[xiaolong2015]

I use the graphql federation 2 directive @interfaceObject in a subgraph:

type HumanResourceOrError @interfaceObject {
  id: ID!
  type: ResourceType!
}

The endpoint http://localhost:8080/graphql/schema.graphql returns a schema with the above type definition, but if I call the entdpoint http://localhost:8080/graphql with the following body, the directive @interfaceObject is missing in the response. Why?

query getService { _service { sdl } }

[jmartisk]

@t1 I assume you are more knowledgeable in this area, would you like to look at it? If not, then I'll try to find some time, but I don't know much about the inner workings of Federation.

[RoKKim]

I stumbled upon the same problem and discovered that a bunch of directives do not appear in the _service query. These are the ones that I've noticed so far:

• @Directive
• @InterfaceObject
• @Tag
• @Shareable
• @Inaccessible
• @Override

Weirdly enough, @key gets added. Example:

• Generated schema:

  directive @custom on OBJECT
  
  type Inventory @custom @interfaceObject @key(fields : "id") {
    deprecatedProducts: [DeprecatedProduct!]!
    id: ID!
  }

• Schema from _service query:

  type Inventory @key(fields : \"id\") {
    deprecatedProducts: [DeprecatedProduct!]!
    id: ID!
  }

[RoKKim]

It seems that this issue is related to the following code in the apollographql/federation-jvm library (com.apollographql.federation.graphqljava.SchemaTransformer#build):

final String sdl;
if (isFederation2) {
  sdl = generateServiceSDLV2(newSchema.codeRegistry(newCodeRegistry.build()).build());
} else {
  // For Federation1, we filter out the federation definitions
  sdl = sdl(originalSchema, queryTypeShouldBeEmpty);
}

Since boolean isFederation2 is hardcoded to false. I found that simply calling com.apollographql.federation.graphqljava.SchemaTransformer#setFederation2 when building graphql.schema.GraphQLSchema resolves the issue for me.

Here are the results when executing the _service query:

directive @custom on OBJECT

type Inventory @custom @interfaceObject @key(fields : "id") {
  deprecatedProducts: [DeprecatedProduct!]!
  id: ID!
}

I've opened pull request #2003 with this fix. Hardcoding the builder to Apollo Federation 2 should be acceptable, right? Alternatively, we could introduce another configuration option to set this value.

A similar problem was reported in this issue in the apollographql/federation-jvm repository:
apollographql/federation-jvm#361

[t1]

@Directive itself shouldn't show up in the schema, as it's just the annotation to create directives. But the others (plus @ComposableDirective) are missing in the IndexInitializer. I'll create a PR.

[t1]

@RoKKim: I wasn't aware of the federation-jvm SchemaTransfomer even being executed. How do you test that? I think you are probably working on a lower level, maybe directly with the graphql-java apis? Most important, how do you add the directives to your application?

The other SmallRye federation annotations like @Key are being added to the Jandex index in the IndexInitializer. I've simply added the missing federation directive annotations.

[RoKKim]

@t1 When executing a query, io.smallrye.graphql.execution.ExecutionService#execute(jakarta.json.JsonObject, java.util.Map<java.lang.String,java.lang.Object>, io.smallrye.graphql.execution.ExecutionResponseWriter, boolean) is called for me.
ExecutionService is initialized in io.smallrye.graphql.cdi.producer.GraphQLProducer#initialize(boolean, graphql.execution.ExecutionStrategy, graphql.execution.ExecutionStrategy) and one of its parameters is io.smallrye.graphql.cdi.producer.GraphQLProducer#graphQLSchema, which is generated in io.smallrye.graphql.bootstrap.Bootstrap#bootstrap(io.smallrye.graphql.schema.model.Schema, boolean). Here com.apollographql.federation.graphqljava.SchemaTransformer#build is called for me in the following section of code:

this.graphQLSchema = Federation.transform(rawSchema)
        .fetchEntities(new FederationDataFetcher(rawSchema.getQueryType(), rawSchema.getCodeRegistry()))
        .resolveEntityType(fetchEntityType())
        .setFederation2(true)
        .build();

Here is the full stack:

java.lang.Thread.State: RUNNABLE
	at com.apollographql.federation.graphqljava.SchemaTransformer.build(SchemaTransformer.java:128)
	at io.smallrye.graphql.bootstrap.Bootstrap.generateGraphQLSchema(Bootstrap.java:212)
	at io.smallrye.graphql.bootstrap.Bootstrap.bootstrap(Bootstrap.java:126)
	at io.smallrye.graphql.cdi.producer.GraphQLProducer.initialize(GraphQLProducer.java:52)
	at io.smallrye.graphql.cdi.producer.GraphQLProducer.initialize(GraphQLProducer.java:42)
	at io.smallrye.graphql.cdi.producer.GraphQLProducer.initialize(GraphQLProducer.java:32)
	at io.smallrye.graphql.cdi.producer.GraphQLProducer.initialize(GraphQLProducer.java:27)
	at io.smallrye.graphql.cdi.producer.GraphQLProducer$Proxy$_$$_WeldClientProxy.initialize(Unknown Source:-1)

I have implemented a custom index initialization where I've added all missing classes during development, which is why I didn't initially notice their absence in IndexInitializer. However, even after adding them, they still do not appear when I call the _service query.

I agree that the @Directive shouldn't show up in the schema, I simply meant to say that when using it, the directive itself does not generate.

[t1]

Oh, sure, now I remember. I even wrote the code that calls the Federation SchemaTransformer myself 🤪

What confused me was, that the full sdl schema string is pregenerated at this time. So I guess we need both of our PRs to be merged 😁

BTW: the Federation directives should also show up in the normal schema endpoint, shouldn't they?

[RoKKim]

When reffering to the schema enpoint, you mean accessing */schema.graphql endpoint right? If so, this seems to already work even without the fixes.
The only thing that concerns me is com.apollographql.federation.graphqljava.printer.ServiceSDLPrinter#generateServiceSDLV2. This method hardcodes the includeSchemaDefinition and includeScalarTypes to true, meaning that io.smallrye.graphql.spi.config.Config will get ignored. If i had to guess, this is the expected behavior when calling the _service SDL query?

[t1]

When reffering to the schema enpoint, you mean accessing */schema.graphql endpoint right?

Yes

this seems to already work even without the fixes.

I would assume only with your custom index initialisation, right?

This method hardcodes the includeSchemaDefinition and includeScalarTypes to true, meaning that io.smallrye.graphql.spi.config.Config will get ignored. If i had to guess, this is the expected behavior when calling the _service SDL query?

I think so, too.

[RoKKim]

I would assume only with your custom index initialisation, right?

I forgot about that, thanks for pointing it out. If I remove them from Indexer in my implementation, then indeed, they do not show up when accessing the schema endpoint.