feat(federation): federation v2.6 support (#1928)

### 📝 Description

Adds Federation v2.6 support

```graphql
directive @Policy(policies: [[federation__Policy!]!]!) on
  | FIELD_DEFINITION
  | OBJECT
  | INTERFACE
  | SCALAR
  | ENUM

scalar federation__Policy
```

`@policy` directive indicates to composition that the target element is
restricted based on authorization policies that are evaluated in a Rhai
script or coprocessor. Refer to the [Apollo Router
article](https://www.apollographql.com/docs/router/configuration/authorization#policy)
for additional details.

### 🔗 Related Issues

N/A

Author: dariuszkuc

examples/federation/docker-compose.yaml

@@ -1,6 +1,6 @@
 services:
   router:
-    image: ghcr.io/apollographql/router:v1.29.1
+    image: ghcr.io/apollographql/router:v1.40.0
     volumes:
       - ./router.yaml:/dist/config/router.yaml
       - ./supergraph.graphql:/dist/config/supergraph.graphql

examples/federation/supergraph.yaml

@@ -1,4 +1,4 @@
-federation_version: =2.5.4
+federation_version: =2.6.3
 subgraphs:
   products:
     routing_url: http://products:8080/graphql

generator/graphql-kotlin-federation/src/main/kotlin/com/expediagroup/graphql/generator/federation/FederatedSchemaGeneratorHooks.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.
@@ -43,6 +43,7 @@ import com.expediagroup.graphql.generator.federation.directives.LinkDirective
 import com.expediagroup.graphql.generator.federation.directives.LinkImport
 import com.expediagroup.graphql.generator.federation.directives.LinkedSpec
 import com.expediagroup.graphql.generator.federation.directives.OVERRIDE_DIRECTIVE_NAME
+import com.expediagroup.graphql.generator.federation.directives.POLICY_DIRECTIVE_NAME
 import com.expediagroup.graphql.generator.federation.directives.PROVIDES_DIRECTIVE_NAME
 import com.expediagroup.graphql.generator.federation.directives.PROVIDES_DIRECTIVE_TYPE
 import com.expediagroup.graphql.generator.federation.directives.REQUIRES_DIRECTIVE_NAME
@@ -52,10 +53,12 @@ import com.expediagroup.graphql.generator.federation.directives.SHAREABLE_DIRECT
 import com.expediagroup.graphql.generator.federation.directives.TAG_DIRECTIVE_NAME
 import com.expediagroup.graphql.generator.federation.directives.keyDirectiveDefinition
 import com.expediagroup.graphql.generator.federation.directives.linkDirectiveDefinition
+import com.expediagroup.graphql.generator.federation.directives.policyDirectiveDefinition
 import com.expediagroup.graphql.generator.federation.directives.providesDirectiveDefinition
 import com.expediagroup.graphql.generator.federation.directives.requiresDirectiveDefinition
 import com.expediagroup.graphql.generator.federation.directives.requiresScopesDirectiveType
 import com.expediagroup.graphql.generator.federation.directives.toAppliedLinkDirective
+import com.expediagroup.graphql.generator.federation.directives.toAppliedPolicyDirective
 import com.expediagroup.graphql.generator.federation.directives.toAppliedRequiresScopesDirective
 import com.expediagroup.graphql.generator.federation.exception.DuplicateSpecificationLinkImport
 import com.expediagroup.graphql.generator.federation.exception.IncorrectFederatedDirectiveUsage
@@ -69,6 +72,7 @@ import com.expediagroup.graphql.generator.federation.types.FIELD_SET_SCALAR_NAME
 import com.expediagroup.graphql.generator.federation.types.FIELD_SET_SCALAR_TYPE
 import com.expediagroup.graphql.generator.federation.types.FieldSetTransformer
 import com.expediagroup.graphql.generator.federation.types.LINK_IMPORT_SCALAR_TYPE
+import com.expediagroup.graphql.generator.federation.types.POLICY_SCALAR_TYPE
 import com.expediagroup.graphql.generator.federation.types.SCOPE_SCALAR_TYPE
 import com.expediagroup.graphql.generator.federation.types.SERVICE_FIELD_DEFINITION
 import com.expediagroup.graphql.generator.federation.types._Service
@@ -149,6 +153,18 @@ open class FederatedSchemaGeneratorHooks(
             }
         }
     }
+    private val policiesScalar: GraphQLScalarType by lazy {
+        POLICY_SCALAR_TYPE.run {
+            val policyScalarName = namespacedTypeName(FEDERATION_SPEC, this.name)
+            if (policyScalarName != this.name) {
+                this.transform {
+                    it.name(policyScalarName)
+                }
+            } else {
+                this
+            }
+        }
+    }
     private val scopesScalar: GraphQLScalarType by lazy {
         SCOPE_SCALAR_TYPE.run {
             val scopesScalarName = namespacedTypeName(FEDERATION_SPEC, this.name)
@@ -252,17 +268,24 @@ open class FederatedSchemaGeneratorHooks(
         EXTERNAL_DIRECTIVE_NAME -> EXTERNAL_DIRECTIVE_TYPE_V2
         KEY_DIRECTIVE_NAME -> keyDirectiveDefinition(fieldSetScalar)
         LINK_DIRECTIVE_NAME -> linkDirectiveDefinition(linkImportScalar)
+        POLICY_DIRECTIVE_NAME -> policyDirectiveDefinition(policiesScalar)
         PROVIDES_DIRECTIVE_NAME -> providesDirectiveDefinition(fieldSetScalar)
         REQUIRES_DIRECTIVE_NAME -> requiresDirectiveDefinition(fieldSetScalar)
         REQUIRES_SCOPE_DIRECTIVE_NAME -> requiresScopesDirectiveType(scopesScalar)
         else -> super.willGenerateDirective(directiveInfo)
     }
 
     override fun willApplyDirective(directiveInfo: DirectiveMetaInformation, directive: GraphQLDirective): GraphQLAppliedDirective? {
-        return if (directiveInfo.effectiveName == REQUIRES_SCOPE_DIRECTIVE_NAME) {
-            directive.toAppliedRequiresScopesDirective(directiveInfo)
-        } else {
-            super.willApplyDirective(directiveInfo, directive)
+        return when (directiveInfo.effectiveName) {
+            REQUIRES_SCOPE_DIRECTIVE_NAME -> {
+                directive.toAppliedRequiresScopesDirective(directiveInfo)
+            }
+            POLICY_DIRECTIVE_NAME -> {
+                directive.toAppliedPolicyDirective(directiveInfo)
+            }
+            else -> {
+                super.willApplyDirective(directiveInfo, directive)
+            }
         }
     }
 

generator/graphql-kotlin-federation/src/main/kotlin/com/expediagroup/graphql/generator/federation/directives/LinkDirective.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.
@@ -32,7 +32,7 @@ const val LINK_SPEC_URL_PREFIX = "$APOLLO_SPEC_URL/$LINK_SPEC"
 const val LINK_SPEC_LATEST_URL = "$LINK_SPEC_URL_PREFIX/v$LINK_SPEC_LATEST_VERSION"
 
 const val FEDERATION_SPEC = "federation"
-const val FEDERATION_SPEC_LATEST_VERSION = "2.5"
+const val FEDERATION_SPEC_LATEST_VERSION = "2.6"
 const val FEDERATION_SPEC_URL_PREFIX = "$APOLLO_SPEC_URL/$FEDERATION_SPEC"
 const val FEDERATION_SPEC_LATEST_URL = "$FEDERATION_SPEC_URL_PREFIX/v$FEDERATION_SPEC_LATEST_VERSION"
 

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

@@ -0,0 +1,32 @@
+/*
+ * 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.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.expediagroup.graphql.generator.federation.directives
+
+import com.expediagroup.graphql.generator.annotations.GraphQLIgnore
+
+/**
+ * Annotation representing authorization policy scalar type that is used by the `@policy directive.
+ *
+ * @param value required authorization policy
+ * @see [com.expediagroup.graphql.generator.federation.types.POLICY_SCALAR_TYPE]
+ */
+@LinkedSpec(FEDERATION_SPEC)
+annotation class Policy(val value: String)
+
+// this is a workaround for JVM lack of support nested arrays as annotation values
+@GraphQLIgnore
+annotation class Policies(val value: Array<Policy>)

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

@@ -0,0 +1,111 @@
+/*
+ * 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.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.expediagroup.graphql.generator.federation.directives
+
+import com.expediagroup.graphql.generator.annotations.GraphQLDirective
+import com.expediagroup.graphql.generator.directives.DirectiveMetaInformation
+import graphql.introspection.Introspection
+import graphql.schema.GraphQLAppliedDirective
+import graphql.schema.GraphQLArgument
+import graphql.schema.GraphQLList
+import graphql.schema.GraphQLNonNull
+import graphql.schema.GraphQLScalarType
+import kotlin.reflect.full.memberProperties
+
+/**
+ * ```graphql
+ * directive @policy(scopes: [[Policy!]!]!) on
+ *     ENUM
+ *   | FIELD_DEFINITION
+ *   | INTERFACE
+ *   | OBJECT
+ *   | SCALAR
+ * ```
+ *
+ *
+ * Directive that is used to indicate that the target element is restricted based on authorization policies that are evaluated in a Rhai script or coprocessor.
+ * Refer to the <a href="https://www.apollographql.com/docs/router/configuration/authorization#policy">Apollo Router article</a> for additional details.
+ *
+ * @see <a href="https://www.apollographql.com/docs/federation/federated-types/federated-directives#policy">@policy definition</a>
+ * @see <a href="https://www.apollographql.com/docs/router/configuration/authorization#policy">Apollo Router @policy documentation</a>
+ */
+@LinkedSpec(FEDERATION_SPEC)
+@Repeatable
+@GraphQLDirective(
+    name = POLICY_DIRECTIVE_NAME,
+    description = POLICY_DIRECTIVE_DESCRIPTION,
+    locations = [
+        Introspection.DirectiveLocation.ENUM,
+        Introspection.DirectiveLocation.FIELD_DEFINITION,
+        Introspection.DirectiveLocation.INTERFACE,
+        Introspection.DirectiveLocation.OBJECT,
+        Introspection.DirectiveLocation.SCALAR,
+    ]
+)
+annotation class PolicyDirective(val policies: Array<Policies>)
+
+internal const val POLICY_DIRECTIVE_NAME = "policy"
+private const val POLICY_DIRECTIVE_DESCRIPTION = "Indicates to composition that the target element is restricted based on authorization policies that are evaluated in a Rhai script or coprocessor"
+private const val POLICIES_ARGUMENT = "policies"
+
+internal fun policyDirectiveDefinition(policies: GraphQLScalarType): graphql.schema.GraphQLDirective = graphql.schema.GraphQLDirective.newDirective()
+    .name(POLICY_DIRECTIVE_NAME)
+    .description(POLICY_DIRECTIVE_DESCRIPTION)
+    .validLocations(
+        Introspection.DirectiveLocation.ENUM,
+        Introspection.DirectiveLocation.FIELD_DEFINITION,
+        Introspection.DirectiveLocation.INTERFACE,
+        Introspection.DirectiveLocation.OBJECT,
+        Introspection.DirectiveLocation.SCALAR
+    )
+    .argument(
+        GraphQLArgument.newArgument()
+            .name(POLICIES_ARGUMENT)
+            .type(
+                GraphQLNonNull.nonNull(
+                    GraphQLList.list(
+                        GraphQLNonNull(
+                            GraphQLList.list(
+                                policies
+                            )
+                        )
+                    )
+                )
+            )
+    )
+    .build()
+
+@Suppress("UNCHECKED_CAST")
+internal fun graphql.schema.GraphQLDirective.toAppliedPolicyDirective(directiveInfo: DirectiveMetaInformation): GraphQLAppliedDirective {
+    // we need to manually transform @policy directive definition as JVM does not support nested array as annotation arguments
+    val annotationPolicies = directiveInfo.directive.annotationClass.memberProperties
+        .first { it.name == POLICIES_ARGUMENT }
+        .call(directiveInfo.directive) as? Array<Policies> ?: emptyArray()
+    val policies = annotationPolicies.map { policiesAnnotation -> policiesAnnotation.value.toList() }
+
+    return this.toAppliedDirective()
+        .transform { appliedDirectiveBuilder ->
+            this.getArgument(POLICIES_ARGUMENT)
+                .toAppliedArgument()
+                .transform { argumentBuilder ->
+                    argumentBuilder.valueProgrammatic(policies)
+                }
+                .let {
+                    appliedDirectiveBuilder.argument(it)
+                }
+        }
+}

generator/graphql-kotlin-federation/src/main/kotlin/com/expediagroup/graphql/generator/federation/directives/RequiresScopesDirective.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.
@@ -73,7 +73,7 @@ internal fun requiresScopesDirectiveType(scopes: GraphQLScalarType): graphql.sch
     )
     .argument(
         GraphQLArgument.newArgument()
-            .name("scopes")
+            .name(SCOPES_ARGUMENT)
             .type(
                 GraphQLNonNull.nonNull(
                     GraphQLList.list(

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

@@ -0,0 +1,74 @@
+/*
+ * 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.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.expediagroup.graphql.generator.federation.types
+
+import com.expediagroup.graphql.generator.federation.directives.Policy
+import com.expediagroup.graphql.generator.federation.exception.CoercingValueToLiteralException
+import graphql.GraphQLContext
+import graphql.Scalars
+import graphql.execution.CoercedVariables
+import graphql.language.StringValue
+import graphql.language.Value
+import graphql.schema.Coercing
+import graphql.schema.CoercingParseLiteralException
+import graphql.schema.CoercingSerializeException
+import graphql.schema.GraphQLScalarType
+import java.util.Locale
+
+internal const val POLICY_SCALAR_NAME = "Policy"
+
+/**
+ * Custom scalar type that is used to represent authentication policy which serializes as a String.
+ */
+internal val POLICY_SCALAR_TYPE: GraphQLScalarType = GraphQLScalarType.newScalar(Scalars.GraphQLString)
+    .name(POLICY_SCALAR_NAME)
+    .description("Federation type representing authorization policy")
+    .coercing(PolicyCoercing)
+    .build()
+
+private object PolicyCoercing : Coercing<Policy, String> {
+    override fun serialize(dataFetcherResult: Any, graphQLContext: GraphQLContext, locale: Locale): String =
+        when (dataFetcherResult) {
+            is Policy -> dataFetcherResult.value
+            else -> throw CoercingSerializeException(
+                "Cannot serialize $dataFetcherResult. Expected type 'Policy' but was '${dataFetcherResult.javaClass.simpleName}'."
+            )
+        }
+
+    override fun parseValue(input: Any, graphQLContext: GraphQLContext, locale: Locale): Policy =
+        when (input) {
+            is Policy -> input
+            is StringValue -> Policy::class.constructors.first().call(input.value)
+            else -> throw CoercingParseLiteralException(
+                "Cannot parse $input to Policy. Expected AST type 'StringValue' but was '${input.javaClass.simpleName}'."
+            )
+        }
+
+    override fun parseLiteral(input: Value<*>, variables: CoercedVariables, graphQLContext: GraphQLContext, locale: Locale): Policy =
+        when (input) {
+            is StringValue -> Policy::class.constructors.first().call(input.value)
+            else -> throw CoercingParseLiteralException(
+                "Cannot parse $input to Policy. Expected AST type 'StringValue' but was '${input.javaClass.simpleName}'."
+            )
+        }
+
+    override fun valueToLiteral(input: Any, graphQLContext: GraphQLContext, locale: Locale): Value<*> =
+        when (input) {
+            is Policy -> StringValue.newStringValue(input.value).build()
+            else -> throw CoercingValueToLiteralException(Policy::class, input)
+        }
+}

generator/graphql-kotlin-federation/src/test/kotlin/com/expediagroup/graphql/generator/federation/FederatedSchemaV2GeneratorTest.kt

@@ -30,7 +30,7 @@ class FederatedSchemaV2GeneratorTest {
     fun `verify can generate federated schema`() {
         val expectedSchema =
             """
-            schema @link(import : ["@external", "@key", "@provides", "@requires", "FieldSet"], url : "https://specs.apollo.dev/federation/v2.5"){
+            schema @link(import : ["@external", "@key", "@provides", "@requires", "FieldSet"], url : "https://specs.apollo.dev/federation/v2.6"){
               query: Query
             }
 

generator/graphql-kotlin-federation/src/test/kotlin/com/expediagroup/graphql/generator/federation/directives/compose/ComposeDirectiveTest.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.
@@ -43,7 +43,7 @@ class ComposeDirectiveTest {
     fun `verify we can generate valid schema with @composeDirective`() {
         val expectedSchema =
             """
-            schema @composeDirective(name : "custom") @link(as : "myspec", import : ["@custom"], url : "https://www.myspecs.dev/myspec/v1.0") @link(import : ["@composeDirective", "@key", "FieldSet"], url : "https://specs.apollo.dev/federation/v2.5"){
+            schema @composeDirective(name : "custom") @link(as : "myspec", import : ["@custom"], url : "https://www.myspecs.dev/myspec/v1.0") @link(import : ["@composeDirective", "@key", "FieldSet"], url : "https://specs.apollo.dev/federation/v2.6"){
               query: Query
             }
 

generator/graphql-kotlin-federation/src/test/kotlin/com/expediagroup/graphql/generator/federation/directives/contact/ContactDirectiveTest.kt

@@ -30,7 +30,7 @@ class ContactDirectiveTest {
     fun `verify we can import federation spec using custom @link`() {
         val expectedSchema =
             """
-            schema @contact(description : "Send emails to foo@myteamname.com", name : "My Team Name", url : "https://myteam.slack.com/room") @link(url : "https://specs.apollo.dev/federation/v2.5"){
+            schema @contact(description : "Send emails to foo@myteamname.com", name : "My Team Name", url : "https://myteam.slack.com/room") @link(url : "https://specs.apollo.dev/federation/v2.6"){
               query: Query
             }
 

generator/graphql-kotlin-federation/src/test/kotlin/com/expediagroup/graphql/generator/federation/directives/link/LinkDirectiveTest.kt

@@ -45,7 +45,7 @@ class LinkDirectiveTest {
     fun `verify we can import federation spec using custom @link`() {
         val expectedSchema =
             """
-            schema @link(as : "fed", import : [{name : "@key", as : "@myKey"}], url : "https://specs.apollo.dev/federation/v2.5"){
+            schema @link(as : "fed", import : [{name : "@key", as : "@myKey"}], url : "https://specs.apollo.dev/federation/v2.6"){
               query: Query
             }