BREAKING: drop Federation v1 support (#1978)

### 📝 Description

Federation v2 was released almost 3 years ago. It is an evolution of the
Federation spec to make it more powerful, flexible and easier to adopt.

It is no longer possible to create Federated Supergraphs targeting v1
composition. Users still using fed v1 shoul migrate ASAP to the fed v2.

### 🔗 Related Issues

---------

Co-authored-by: Samuel Vazquez <sam_2f@hotmail.com>

examples/client/server/src/main/kotlin/com/expediagroup/graphql/examples/client/server/CustomFederatedHooks.kt

@@ -11,7 +11,7 @@ import java.util.UUID
 import kotlin.reflect.KType
 
 @Component
-class CustomFederatedHooks(resolvers: List<FederatedTypeResolver>) : FederatedSchemaGeneratorHooks(resolvers, true) {
+class CustomFederatedHooks(resolvers: List<FederatedTypeResolver>) : FederatedSchemaGeneratorHooks(resolvers,) {
     override fun willGenerateGraphQLType(type: KType): GraphQLType? = when (type.classifier) {
         UUID::class -> graphqlUUIDType
         ULocale::class -> graphqlULocaleType

generator/graphql-kotlin-federation/build.gradle.kts

@@ -27,7 +27,7 @@ tasks {
                 limit {
                     counter = "BRANCH"
                     value = "COVEREDRATIO"
-                    minimum = "0.83".toBigDecimal()
+                    minimum = "0.82".toBigDecimal()
                 }
             }
         }

generator/graphql-kotlin-federation/src/main/kotlin/com/expediagroup/graphql/generator/federation/directives/ExternalDirective.kt

@@ -21,10 +21,6 @@ import graphql.introspection.Introspection.DirectiveLocation
 
 /**
  * ```graphql
- * # federation v1 definition
- * directive @external on FIELD_DEFINITION
- *
- * # federation v2 definition
  * directive @external on OBJECT | FIELD_DEFINITION
  * ```
  *
@@ -73,12 +69,6 @@ internal const val EXTERNAL_DIRECTIVE_NAME = "external"
 private const val EXTERNAL_DIRECTIVE_DESCRIPTION = "Marks target field as external meaning it will be resolved by federated schema"
 
 internal val EXTERNAL_DIRECTIVE_TYPE: graphql.schema.GraphQLDirective = graphql.schema.GraphQLDirective.newDirective()
-    .name(EXTERNAL_DIRECTIVE_NAME)
-    .description(EXTERNAL_DIRECTIVE_DESCRIPTION)
-    .validLocations(DirectiveLocation.FIELD_DEFINITION)
-    .build()
-
-internal val EXTERNAL_DIRECTIVE_TYPE_V2: graphql.schema.GraphQLDirective = graphql.schema.GraphQLDirective.newDirective()
     .name(EXTERNAL_DIRECTIVE_NAME)
     .description(EXTERNAL_DIRECTIVE_DESCRIPTION)
     .validLocations(DirectiveLocation.OBJECT, DirectiveLocation.FIELD_DEFINITION)

generator/graphql-kotlin-federation/src/main/kotlin/com/expediagroup/graphql/generator/federation/types/FieldSet.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023 Expedia, Inc
+ * Copyright 2024 Expedia, Inc
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,10 +29,6 @@ import graphql.schema.CoercingSerializeException
 import graphql.schema.GraphQLArgument
 import graphql.schema.GraphQLNonNull
 import graphql.schema.GraphQLScalarType
-import graphql.schema.GraphQLSchemaElement
-import graphql.schema.GraphQLTypeVisitorStub
-import graphql.util.TraversalControl
-import graphql.util.TraverserContext
 import java.util.Locale
 
 internal const val FIELD_SET_SCALAR_NAME = "FieldSet"
@@ -91,18 +87,3 @@ private object FieldSetCoercing : Coercing<FieldSet, String> {
             else -> throw CoercingValueToLiteralException(FieldSet::class, input)
         }
 }
-
-/**
- * Renames FieldSet scalar (used in Federation V2) to _FieldSet (used in Federation V1).
- */
-class FieldSetTransformer : GraphQLTypeVisitorStub() {
-    override fun visitGraphQLScalarType(node: GraphQLScalarType, context: TraverserContext<GraphQLSchemaElement>): TraversalControl {
-        if (node.name == "FieldSet") {
-            val legacyFieldSetScalar = node.transform {
-                it.name("_FieldSet")
-            }
-            return changeNode(context, legacyFieldSetScalar)
-        }
-        return super.visitGraphQLScalarType(node, context)
-    }
-}

generator/graphql-kotlin-federation/src/test/kotlin/com/expediagroup/graphql/generator/federation/FederatedSchemaGeneratorTest.kt

@@ -23,6 +23,7 @@ import com.expediagroup.graphql.generator.federation.data.queries.simple.SimpleQ
 import com.expediagroup.graphql.generator.federation.directives.KEY_DIRECTIVE_NAME
 import com.expediagroup.graphql.generator.federation.types.ENTITY_UNION_NAME
 import graphql.schema.GraphQLUnionType
+import org.junit.jupiter.api.Assertions
 import org.junit.jupiter.api.Assertions.assertEquals
 import org.junit.jupiter.api.Test
 import kotlin.test.assertNotNull
@@ -33,7 +34,7 @@ class FederatedSchemaGeneratorTest {
     fun `verify can generate federated schema`() {
         val expectedSchema =
             """
-            schema {
+            schema @link(import : ["@external", "@key", "@provides", "@requires", "FieldSet"], url : "https://specs.apollo.dev/federation/v2.6"){
               query: Query
             }
 
@@ -45,11 +46,8 @@ class FederatedSchemaGeneratorTest {
                 reason: String = "No longer supported"
               ) on FIELD_DEFINITION | ARGUMENT_DEFINITION | ENUM_VALUE | INPUT_FIELD_DEFINITION
 
-            "Marks target object as extending part of the federated schema"
-            directive @extends on OBJECT | INTERFACE
-
             "Marks target field as external meaning it will be resolved by federated schema"
-            directive @external on FIELD_DEFINITION
+            directive @external on OBJECT | FIELD_DEFINITION
 
             "Directs the executor to include this field or fragment only when the `if` argument is true"
             directive @include(
@@ -58,16 +56,19 @@ class FederatedSchemaGeneratorTest {
               ) on FIELD | FRAGMENT_SPREAD | INLINE_FRAGMENT
 
             "Space separated list of primary keys needed to access federated object"
-            directive @key(fields: _FieldSet!) repeatable on OBJECT | INTERFACE
+            directive @key(fields: FieldSet!, resolvable: Boolean = true) repeatable on OBJECT | INTERFACE
+
+            "Links definitions within the document to external schemas."
+            directive @link(as: String, import: [link__Import], url: String!) repeatable on SCHEMA
 
             "Indicates an Input Object is a OneOf Input Object."
             directive @oneOf on INPUT_OBJECT
 
             "Specifies the base type field set that will be selectable by the gateway"
-            directive @provides(fields: _FieldSet!) on FIELD_DEFINITION
+            directive @provides(fields: FieldSet!) on FIELD_DEFINITION
 
             "Specifies required input field set from the base type for a resolver"
-            directive @requires(fields: _FieldSet!) on FIELD_DEFINITION
+            directive @requires(fields: FieldSet!) on FIELD_DEFINITION
 
             "Directs the executor to skip this field or fragment when the `if` argument is true."
             directive @skip(
@@ -81,33 +82,33 @@ class FederatedSchemaGeneratorTest {
                 url: String!
               ) on SCALAR
 
-            interface Product @extends @key(fields : "id") @key(fields : "upc") {
-              id: String! @external
+            interface Product @key(fields : "id", resolvable : true) @key(fields : "upc", resolvable : true) {
+              id: String!
               reviews: [Review!]!
-              upc: String! @external
+              upc: String!
             }
 
             union _Entity = Author | Book | User
 
-            type Author @extends @key(fields : "authorId") {
-              authorId: Int! @external
-              name: String! @external
+            type Author @key(fields : "authorId", resolvable : true) {
+              authorId: Int!
+              name: String!
             }
 
-            type Book implements Product @extends @key(fields : "id") @key(fields : "upc") {
+            type Book implements Product @key(fields : "id", resolvable : true) @key(fields : "upc", resolvable : true) {
               author: User! @provides(fields : "name")
-              id: String! @external
+              id: String!
               reviews: [Review!]!
               shippingCost: String! @requires(fields : "weight")
-              upc: String! @external
+              upc: String!
               weight: Float! @external
             }
 
             type CustomScalar {
               value: String!
             }
 
-            type Query @extends {
+            type Query {
               "Union of all types that use the @key directive, including both types native to the schema and extended types"
               _entities(representations: [_Any!]!): [_Entity]!
               _service: _Service!
@@ -120,30 +121,31 @@ class FederatedSchemaGeneratorTest {
               id: String!
             }
 
-            type User @extends @key(fields : "userId") {
-              name: String! @external
-              userId: Int! @external
+            type User @key(fields : "userId", resolvable : true) {
+              name: String!
+              userId: Int!
             }
 
             type _Service {
               sdl: String!
             }
 
+            "Federation type representing set of fields"
+            scalar FieldSet
+
             "Federation scalar type used to represent any external entities passed to _entities query."
             scalar _Any
 
-            "Federation type representing set of fields"
-            scalar _FieldSet
+            scalar link__Import
             """.trimIndent()
 
         val config = FederatedSchemaGeneratorConfig(
-            supportedPackages = listOf("com.expediagroup.graphql.generator.federation.data.queries.federated.v1"),
-            hooks = FederatedSchemaGeneratorHooks(emptyList(), optInFederationV2 = false)
+            supportedPackages = listOf("com.expediagroup.graphql.generator.federation.data.queries.federated"),
+            hooks = FederatedSchemaGeneratorHooks(emptyList())
         )
 
         val schema = toFederatedSchema(config = config)
-
-        assertEquals(expectedSchema, schema.print().trim())
+        Assertions.assertEquals(expectedSchema, schema.print().trim())
         val productType = schema.getObjectType("Book")
         assertNotNull(productType)
         assertNotNull(productType.hasAppliedDirective(KEY_DIRECTIVE_NAME))
@@ -157,7 +159,7 @@ class FederatedSchemaGeneratorTest {
     fun `verify generator does not add federation queries for non-federated schemas`() {
         val expectedSchema =
             """
-            schema {
+            schema @link(url : "https://specs.apollo.dev/federation/v2.6"){
               query: Query
             }
 
@@ -167,30 +169,18 @@ class FederatedSchemaGeneratorTest {
                 reason: String = "No longer supported"
               ) on FIELD_DEFINITION | ARGUMENT_DEFINITION | ENUM_VALUE | INPUT_FIELD_DEFINITION
 
-            "Marks target object as extending part of the federated schema"
-            directive @extends on OBJECT | INTERFACE
-
-            "Marks target field as external meaning it will be resolved by federated schema"
-            directive @external on FIELD_DEFINITION
-
             "Directs the executor to include this field or fragment only when the `if` argument is true"
             directive @include(
                 "Included when true."
                 if: Boolean!
               ) on FIELD | FRAGMENT_SPREAD | INLINE_FRAGMENT
 
-            "Space separated list of primary keys needed to access federated object"
-            directive @key(fields: _FieldSet!) repeatable on OBJECT | INTERFACE
+            "Links definitions within the document to external schemas."
+            directive @link(as: String, import: [link__Import], url: String!) repeatable on SCHEMA
 
             "Indicates an Input Object is a OneOf Input Object."
             directive @oneOf on INPUT_OBJECT
 
-            "Specifies the base type field set that will be selectable by the gateway"
-            directive @provides(fields: _FieldSet!) on FIELD_DEFINITION
-
-            "Specifies required input field set from the base type for a resolver"
-            directive @requires(fields: _FieldSet!) on FIELD_DEFINITION
-
             "Directs the executor to skip this field or fragment when the `if` argument is true."
             directive @skip(
                 "Skipped when true."
@@ -203,7 +193,7 @@ class FederatedSchemaGeneratorTest {
                 url: String!
               ) on SCALAR
 
-            type Query @extends {
+            type Query {
               _service: _Service!
               hello(name: String!): String!
             }
@@ -212,27 +202,56 @@ class FederatedSchemaGeneratorTest {
               sdl: String!
             }
 
-            "Federation type representing set of fields"
-            scalar _FieldSet
+            scalar link__Import
             """.trimIndent()
 
         val config = FederatedSchemaGeneratorConfig(
             supportedPackages = listOf("com.expediagroup.graphql.generator.federation.data.queries.simple"),
-            hooks = FederatedSchemaGeneratorHooks(emptyList(), optInFederationV2 = false)
+            hooks = FederatedSchemaGeneratorHooks(emptyList())
         )
 
         val schema = toFederatedSchema(config, listOf(TopLevelObject(SimpleQuery())))
         assertEquals(expectedSchema, schema.print().trim())
     }
 
     @Test
-    fun `verify a nested federated schema still works`() {
+    fun `verify a schema with self nested query still works`() {
         val expectedSchema =
             """
-            schema {
+            schema @link(url : "https://specs.apollo.dev/federation/v2.6"){
               query: Query
             }
 
+            "Marks the field, argument, input field or enum value as deprecated"
+            directive @deprecated(
+                "The reason for the deprecation"
+                reason: String = "No longer supported"
+              ) on FIELD_DEFINITION | ARGUMENT_DEFINITION | ENUM_VALUE | INPUT_FIELD_DEFINITION
+
+            "Directs the executor to include this field or fragment only when the `if` argument is true"
+            directive @include(
+                "Included when true."
+                if: Boolean!
+              ) on FIELD | FRAGMENT_SPREAD | INLINE_FRAGMENT
+
+            "Links definitions within the document to external schemas."
+            directive @link(as: String, import: [link__Import], url: String!) repeatable on SCHEMA
+
+            "Indicates an Input Object is a OneOf Input Object."
+            directive @oneOf on INPUT_OBJECT
+
+            "Directs the executor to skip this field or fragment when the `if` argument is true."
+            directive @skip(
+                "Skipped when true."
+                if: Boolean!
+              ) on FIELD | FRAGMENT_SPREAD | INLINE_FRAGMENT
+
+            "Exposes a URL that specifies the behaviour of this scalar."
+            directive @specifiedBy(
+                "The URL that specifies the behaviour of this scalar."
+                url: String!
+              ) on SCALAR
+
             type Query {
               _service: _Service!
               getSimpleNestedObject: [SelfReferenceObject]!
@@ -248,16 +267,15 @@ class FederatedSchemaGeneratorTest {
               sdl: String!
             }
 
-            "Federation type representing set of fields"
-            scalar _FieldSet
+            scalar link__Import
             """.trimIndent()
 
         val config = FederatedSchemaGeneratorConfig(
             supportedPackages = listOf("com.expediagroup.graphql.generator.federation.data.queries.simple"),
-            hooks = FederatedSchemaGeneratorHooks(emptyList(), optInFederationV2 = false)
+            hooks = FederatedSchemaGeneratorHooks(emptyList())
         )
 
         val schema = toFederatedSchema(config, listOf(TopLevelObject(NestedQuery())))
-        assertEquals(expectedSchema, schema.print(includeDirectives = false).trim())
+        assertEquals(expectedSchema, schema.print(includeDirectives = true).trim())
     }
 }