feat: add support of field selection reasons extensions

execution/engine/config_factory_federation.go

@@ -306,7 +306,7 @@ func (f *FederationEngineConfigFactory) subgraphDataSourceConfiguration(engineCo
 			subscriptionUseSSE = *in.CustomGraphql.Subscription.UseSSE
 		}
 	}
-	// dataSourceRules := FetchURLRules(&routerEngineConfig.Headers, routerConfig.Subgraphs, subscriptionUrl)
+	// dataSourceRules := FetchURLRules(&routerEngineConfig.Headers, routerConfig.BySubgraphs, subscriptionUrl)
 	// forwardedClientHeaders, forwardedClientRegexps, err := PropagatedHeaders(dataSourceRules)
 	// if err != nil {
 	// 	return nil, fmt.Errorf("error parsing header rules for data source %s: %w", in.Id, err)

execution/engine/execution_engine_test.go

@@ -215,6 +215,7 @@ type _executionTestOptions struct {
 	resolvableOptions resolve.ResolvableOptions
 
 	apolloRouterCompatibilitySubrequestHTTPError bool
+	propagateFieldsRequestedBy                   bool
 }
 
 type executionTestOptions func(*_executionTestOptions)
@@ -262,6 +263,7 @@ func TestExecutionEngine_Execute(t *testing.T) {
 				MaxConcurrency:    1024,
 				ResolvableOptions: opts.resolvableOptions,
 				ApolloRouterCompatibilitySubrequestHTTPError: opts.apolloRouterCompatibilitySubrequestHTTPError,
+				PropagateFieldsRequestedBy:                   opts.propagateFieldsRequestedBy,
 			})
 			require.NoError(t, err)
 
@@ -822,6 +824,59 @@ func TestExecutionEngine_Execute(t *testing.T) {
 		},
 	))
 
+	t.Run("execute simple hero operation with propagating to subgraphs reason for fields being requested", runWithoutError(
+		ExecutionEngineTestCase{
+			schema:    graphql.StarwarsSchema(t),
+			operation: graphql.LoadStarWarsQuery(starwars.FileSimpleHeroQuery, nil),
+			dataSources: []plan.DataSource{
+				mustGraphqlDataSourceConfiguration(t,
+					"id",
+					mustFactory(t,
+						testNetHttpClient(t, roundTripperTestCase{
+							expectedHost:     "example.com",
+							expectedPath:     "/",
+							expectedBody:     `{"query":"{hero {name}}","extensions":{"FieldsRequestedBy":[{"__typename":"Character","field":"name","byUser":true},{"__typename":"Query","field":"hero","byUser":true}]}}`,
+							sendResponseBody: `{"data":{"hero":{"name":"Luke Skywalker"}}}`,
+							sendStatusCode:   200,
+						}),
+					),
+					&plan.DataSourceMetadata{
+						RootNodes: []plan.TypeField{
+							{
+								TypeName:            "Query",
+								FieldNames:          []string{"hero"},
+								ProtectedFieldNames: []string{"hero"},
+							},
+						},
+						ChildNodes: []plan.TypeField{
+							{
+								TypeName:            "Character",
+								FieldNames:          []string{"name"},
+								ProtectedFieldNames: []string{"name"},
+							},
+						},
+					},
+					mustConfiguration(t, graphql_datasource.ConfigurationInput{
+						Fetch: &graphql_datasource.FetchConfiguration{
+							URL:    "https://example.com/",
+							Method: "POST",
+						},
+						SchemaConfiguration: mustSchemaConfig(
+							t,
+							nil,
+							string(graphql.StarwarsSchema(t).RawSchema()),
+						),
+					}),
+				),
+			},
+			fields:           []plan.FieldConfiguration{},
+			expectedResponse: `{"data":{"hero":{"name":"Luke Skywalker"}}}`,
+		},
+		func(eto *_executionTestOptions) {
+			eto.propagateFieldsRequestedBy = true
+		},
+	))
+
 	t.Run("execute simple hero operation with graphql data source and empty errors list", runWithoutError(
 		ExecutionEngineTestCase{
 			schema:    graphql.StarwarsSchema(t),
@@ -4291,117 +4346,130 @@ func TestExecutionEngine_Execute(t *testing.T) {
 				}
 			`
 
-		datasources := []plan.DataSource{
-			mustGraphqlDataSourceConfiguration(t,
-				"id-1",
-				mustFactory(t,
-					testNetHttpClient(t, roundTripperTestCase{
-						expectedHost:     "first",
-						expectedPath:     "/",
-						expectedBody:     `{"query":"{accounts {__typename ... on User {some {__typename id}} ... on Admin {some {__typename id}}}}"}`,
-						sendResponseBody: `{"data":{"accounts":[{"__typename":"User","some":{"__typename":"User","id":"1"}},{"__typename":"Admin","some":{"__typename":"User","id":"2"}},{"__typename":"User","some":{"__typename":"User","id":"3"}}]}}`,
-						sendStatusCode:   200,
-					}),
-				),
-				&plan.DataSourceMetadata{
-					RootNodes: []plan.TypeField{
-						{
-							TypeName:   "Query",
-							FieldNames: []string{"accounts"},
-						},
-						{
-							TypeName:   "User",
-							FieldNames: []string{"id", "some"},
-						},
-						{
-							TypeName:   "Admin",
-							FieldNames: []string{"id", "some"},
-						},
-					},
-					ChildNodes: []plan.TypeField{
-						{
-							TypeName:   "Node",
-							FieldNames: []string{"id", "title", "some"},
-						},
-					},
-					FederationMetaData: plan.FederationMetaData{
-						Keys: plan.FederationFieldConfigurations{
+		makeDataSource := func(t *testing.T, expectRequestedBy bool) []plan.DataSource {
+			var expectedBody1 string
+			var expectedBody2 string
+			if !expectRequestedBy {
+				expectedBody1 = `{"query":"{accounts {__typename ... on User {some {__typename id}} ... on Admin {some {__typename id}}}}"}`
+			} else {
+				expectedBody1 = `{"query":"{accounts {__typename ... on User {some {__typename id}} ... on Admin {some {__typename id}}}}","extensions":{"FieldsRequestedBy":[{"__typename":"User","field":"id","bySubgraphs":["id-2"],"reasonIsKey":true},{"__typename":"User","field":"id","byUser":true},{"__typename":"Admin","field":"some","byUser":true}]}}`
+			}
+			expectedBody2 = `{"query":"query($representations: [_Any!]!){_entities(representations: $representations){... on User {__typename title}}}","variables":{"representations":[{"__typename":"User","id":"1"},{"__typename":"User","id":"3"}]}}`
+
+			return []plan.DataSource{
+				mustGraphqlDataSourceConfiguration(t,
+					"id-1",
+					mustFactory(t,
+						testNetHttpClient(t, roundTripperTestCase{
+							expectedHost:     "first",
+							expectedPath:     "/",
+							expectedBody:     expectedBody1,
+							sendResponseBody: `{"data":{"accounts":[{"__typename":"User","some":{"__typename":"User","id":"1"}},{"__typename":"Admin","some":{"__typename":"User","id":"2"}},{"__typename":"User","some":{"__typename":"User","id":"3"}}]}}`,
+							sendStatusCode:   200,
+						}),
+					),
+					&plan.DataSourceMetadata{
+						RootNodes: []plan.TypeField{
+							{
+								TypeName:   "Query",
+								FieldNames: []string{"accounts"},
+							},
 							{
-								TypeName:     "User",
-								SelectionSet: "id",
+								TypeName:            "User",
+								FieldNames:          []string{"id", "some"},
+								ProtectedFieldNames: []string{"id"},
 							},
 							{
-								TypeName:     "Admin",
-								SelectionSet: "id",
+								TypeName:            "Admin",
+								FieldNames:          []string{"id", "some"},
+								ProtectedFieldNames: []string{"some"},
+							},
+						},
+						ChildNodes: []plan.TypeField{
+							{
+								TypeName:   "Node",
+								FieldNames: []string{"id", "title", "some"},
+							},
+						},
+						FederationMetaData: plan.FederationMetaData{
+							Keys: plan.FederationFieldConfigurations{
+								{
+									TypeName:     "User",
+									SelectionSet: "id",
+								},
+								{
+									TypeName:     "Admin",
+									SelectionSet: "id",
+								},
 							},
 						},
 					},
-				},
-				mustConfiguration(t, graphql_datasource.ConfigurationInput{
-					Fetch: &graphql_datasource.FetchConfiguration{
-						URL:    "https://first/",
-						Method: "POST",
-					},
-					SchemaConfiguration: mustSchemaConfig(
-						t,
-						&graphql_datasource.FederationConfiguration{
-							Enabled:    true,
-							ServiceSDL: firstSubgraphSDL,
+					mustConfiguration(t, graphql_datasource.ConfigurationInput{
+						Fetch: &graphql_datasource.FetchConfiguration{
+							URL:    "https://first/",
+							Method: "POST",
 						},
-						firstSubgraphSDL,
-					),
-				}),
-			),
-			mustGraphqlDataSourceConfiguration(t,
-				"id-2",
-				mustFactory(t,
-					testNetHttpClient(t, roundTripperTestCase{
-						expectedHost:     "second",
-						expectedPath:     "/",
-						expectedBody:     `{"query":"query($representations: [_Any!]!){_entities(representations: $representations){... on User {__typename title}}}","variables":{"representations":[{"__typename":"User","id":"1"},{"__typename":"User","id":"3"}]}}`,
-						sendResponseBody: `{"data":{"_entities":[{"__typename":"User","title":"User1"},{"__typename":"User","title":"User3"}]}}`,
-						sendStatusCode:   200,
+						SchemaConfiguration: mustSchemaConfig(
+							t,
+							&graphql_datasource.FederationConfiguration{
+								Enabled:    true,
+								ServiceSDL: firstSubgraphSDL,
+							},
+							firstSubgraphSDL,
+						),
 					}),
 				),
-				&plan.DataSourceMetadata{
-					RootNodes: []plan.TypeField{
-						{
-							TypeName:   "User",
-							FieldNames: []string{"id", "name", "title"},
-						},
-						{
-							TypeName:   "Admin",
-							FieldNames: []string{"id", "adminName", "title"},
-						},
-					},
-					FederationMetaData: plan.FederationMetaData{
-						Keys: plan.FederationFieldConfigurations{
+				mustGraphqlDataSourceConfiguration(t,
+					"id-2",
+					mustFactory(t,
+						testNetHttpClient(t, roundTripperTestCase{
+							expectedHost:     "second",
+							expectedPath:     "/",
+							expectedBody:     expectedBody2,
+							sendResponseBody: `{"data":{"_entities":[{"__typename":"User","title":"User1"},{"__typename":"User","title":"User3"}]}}`,
+							sendStatusCode:   200,
+						}),
+					),
+					&plan.DataSourceMetadata{
+						RootNodes: []plan.TypeField{
 							{
-								TypeName:     "User",
-								SelectionSet: "id",
+								TypeName:   "User",
+								FieldNames: []string{"id", "name", "title"},
 							},
 							{
-								TypeName:     "Admin",
-								SelectionSet: "id",
+								TypeName:   "Admin",
+								FieldNames: []string{"id", "adminName", "title"},
+							},
+						},
+						FederationMetaData: plan.FederationMetaData{
+							Keys: plan.FederationFieldConfigurations{
+								{
+									TypeName:     "User",
+									SelectionSet: "id",
+								},
+								{
+									TypeName:     "Admin",
+									SelectionSet: "id",
+								},
 							},
 						},
 					},
-				},
-				mustConfiguration(t, graphql_datasource.ConfigurationInput{
-					Fetch: &graphql_datasource.FetchConfiguration{
-						URL:    "https://second/",
-						Method: "POST",
-					},
-					SchemaConfiguration: mustSchemaConfig(
-						t,
-						&graphql_datasource.FederationConfiguration{
-							Enabled:    true,
-							ServiceSDL: secondSubgraphSDL,
+					mustConfiguration(t, graphql_datasource.ConfigurationInput{
+						Fetch: &graphql_datasource.FetchConfiguration{
+							URL:    "https://second/",
+							Method: "POST",
 						},
-						secondSubgraphSDL,
-					),
-				}),
-			),
+						SchemaConfiguration: mustSchemaConfig(
+							t,
+							&graphql_datasource.FederationConfiguration{
+								Enabled:    true,
+								ServiceSDL: secondSubgraphSDL,
+							},
+							secondSubgraphSDL,
+						),
+					}),
+				),
+			}
 		}
 
 		t.Run("run", runWithoutError(ExecutionEngineTestCase{
@@ -4432,9 +4500,46 @@ func TestExecutionEngine_Execute(t *testing.T) {
 					}`,
 				}
 			},
-			dataSources:      datasources,
+			dataSources:      makeDataSource(t, false),
 			expectedResponse: `{"data":{"accounts":[{"some":{"title":"User1"}},{"some":{"__typename":"User","id":"2"}},{"some":{"title":"User3"}}]}}`,
 		}))
+
+		t.Run("run with extension", runWithoutError(
+			ExecutionEngineTestCase{
+				schema: func(t *testing.T) *graphql.Schema {
+					t.Helper()
+					parseSchema, err := graphql.NewSchemaFromString(definition)
+					require.NoError(t, err)
+					return parseSchema
+				}(t),
+				operation: func(t *testing.T) graphql.Request {
+					return graphql.Request{
+						OperationName: "Accounts",
+						Query: `
+					query Accounts {
+						accounts {
+							... on User {
+								some {
+									title
+								}
+							}
+							... on Admin {
+								some {
+									__typename
+									id
+								}
+							}
+						}
+					}`,
+					}
+				},
+				dataSources:      makeDataSource(t, true),
+				expectedResponse: `{"data":{"accounts":[{"some":{"title":"User1"}},{"some":{"__typename":"User","id":"2"}},{"some":{"title":"User3"}}]}}`,
+			},
+			func(eto *_executionTestOptions) {
+				eto.propagateFieldsRequestedBy = true
+			},
+		))
 	})
 }
 
@@ -4592,12 +4697,10 @@ func BenchmarkIntrospection(b *testing.B) {
 
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
-
 	type benchCase struct {
 		engine *ExecutionEngine
 		writer *graphql.EngineResultWriter
 	}
-
 	newEngine := func() *ExecutionEngine {
 		engine, err := NewExecutionEngine(ctx, abstractlogger.NoopLogger, engineConf, resolve.ResolverOptions{
 			MaxConcurrency: 1024,
@@ -4649,12 +4752,10 @@ func BenchmarkIntrospection(b *testing.B) {
 func BenchmarkExecutionEngine(b *testing.B) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
-
 	type benchCase struct {
 		engine *ExecutionEngine
 		writer *graphql.EngineResultWriter
 	}
-
 	newEngine := func() *ExecutionEngine {
 		schema, err := graphql.NewSchemaFromString(`type Query { hello: String}`)
 		require.NoError(b, err)