feat: improve error reporting for subgraphs (#705)

v2/examples/federation/go.mod

@@ -1,6 +1,8 @@
 module github.com/wundergraph/graphql-go-tools/v2/examples/federation
 
-go 1.18
+go 1.21
+
+toolchain go1.21.0
 
 require (
 	github.com/99designs/gqlgen v0.17.22
@@ -24,7 +26,7 @@ require (
 	github.com/eclipse/paho.mqtt.golang v1.2.0 // indirect
 	github.com/gobwas/httphead v0.0.0-20180130184737-2c6c146eadee // indirect
 	github.com/gobwas/pool v0.2.0 // indirect
-	github.com/google/uuid v1.1.1 // indirect
+	github.com/google/uuid v1.4.0 // indirect
 	github.com/hashicorp/golang-lru v0.5.4 // indirect
 	github.com/huandu/xstrings v1.2.1 // indirect
 	github.com/imdario/mergo v0.3.8 // indirect

v2/examples/federation/go.sum

@@ -63,6 +63,7 @@ github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/
 github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
 github.com/google/uuid v1.1.1 h1:Gkbcsh/GbpXz7lPftLA3P6TYMwjCLYm83jiFQZF/3gY=
 github.com/google/uuid v1.1.1/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/google/uuid v1.4.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/gorilla/websocket v1.4.1/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/gorilla/websocket v1.5.0 h1:PPwGk2jz7EePpoHN/+ClbZu8SPxiqlu12wZP/3sWmnc=
 github.com/gorilla/websocket v1.5.0/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=

v2/go.mod

@@ -35,6 +35,8 @@ require (
 	github.com/agnivade/levenshtein v1.1.1 // indirect
 	github.com/gobwas/httphead v0.0.0-20180130184737-2c6c146eadee // indirect
 	github.com/gobwas/pool v0.2.0 // indirect
+	github.com/hashicorp/errwrap v1.0.0 // indirect
+	github.com/hashicorp/go-multierror v1.1.1 // indirect
 	github.com/klauspost/compress v1.14.4 // indirect
 	github.com/kr/pretty v0.3.1 // indirect
 	github.com/logrusorgru/aurora/v3 v3.0.0 // indirect

v2/go.sum

@@ -57,6 +57,10 @@ github.com/google/uuid v1.4.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+
 github.com/gorilla/websocket v1.4.1/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/gorilla/websocket v1.5.0 h1:PPwGk2jz7EePpoHN/+ClbZu8SPxiqlu12wZP/3sWmnc=
 github.com/gorilla/websocket v1.5.0/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
+github.com/hashicorp/errwrap v1.0.0 h1:hLrqtEDnRye3+sgx6z4qVLNuviH3MR5aQ0ykNJa/UYA=
+github.com/hashicorp/errwrap v1.0.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
+github.com/hashicorp/go-multierror v1.1.1 h1:H5DkEtf6CXdFp0N0Em5UCwQpXMWke8IA0+lD48awMYo=
+github.com/hashicorp/go-multierror v1.1.1/go.mod h1:iw975J/qwKPdAO1clOe2L8331t/9/fmwbPZ6JB6eMoM=
 github.com/hashicorp/golang-lru v0.5.4 h1:YDjusn29QI/Das2iO9M0BHnIbxPeyuCHsjMW+lJfyTc=
 github.com/hashicorp/golang-lru v0.5.4/go.mod h1:iADmTwqILo4mZ8BN3D2Q6+9jd8WM5uGBxy+E8yxSoD4=
 github.com/jensneuse/abstractlogger v0.0.4 h1:sa4EH8fhWk3zlTDbSncaWKfwxYM8tYSlQ054ETLyyQY=

v2/pkg/engine/resolve/context.go

@@ -5,6 +5,7 @@ import (
 	"net/http"
 	"time"
 
+	"github.com/hashicorp/go-multierror"
 	"go.uber.org/atomic"
 )
 
@@ -17,6 +18,16 @@ type Context struct {
 	InitialPayload        []byte
 	Extensions            []byte
 	Stats                 Stats
+
+	subgraphErrors error
+}
+
+func (c *Context) SubgraphErrors() error {
+	return c.subgraphErrors
+}
+
+func (c *Context) appendSubgraphError(err error) {
+	c.subgraphErrors = multierror.Append(c.subgraphErrors, err)
 }
 
 type Stats struct {
@@ -78,6 +89,7 @@ func (c *Context) Free() {
 	c.RequestTracingOptions.DisableAll()
 	c.Extensions = nil
 	c.Stats.Reset()
+	c.subgraphErrors = nil
 }
 
 type traceStartKey struct{}

v2/pkg/engine/resolve/loader.go

@@ -89,6 +89,7 @@ func (l *Loader) renderPath() string {
 			builder.WriteString("mutation")
 		case ast.OperationTypeSubscription:
 			builder.WriteString("subscription")
+		case ast.OperationTypeUnknown:
 		}
 	}
 	if len(l.path) == 0 {
@@ -342,7 +343,10 @@ func (l *Loader) mergeErrors(ref int) {
 
 func (l *Loader) mergeResult(res *result, items []int) error {
 	defer pool.BytesBuffer.Put(res.out)
-	if res.fetchAborted {
+	if res.err != nil {
+		return l.renderErrorsFailedToFetch(res)
+	}
+	if res.fetchSkipped {
 		return nil
 	}
 	if res.out.Len() == 0 {
@@ -452,8 +456,18 @@ type result struct {
 	postProcessing   PostProcessingConfiguration
 	out              *bytes.Buffer
 	batchStats       [][]int
-	fetchAborted     bool
+	fetchSkipped     bool
 	nestedMergeItems []*result
+
+	err          error
+	subgraphName string
+}
+
+func (r *result) init(postProcessing PostProcessingConfiguration, info *FetchInfo) {
+	r.postProcessing = postProcessing
+	if info != nil {
+		r.subgraphName = info.DataSourceID
+	}
 }
 
 var (
@@ -475,26 +489,27 @@ func (l *Loader) renderErrorsInvalidInput(out *bytes.Buffer) error {
 	return nil
 }
 
-var (
-	errorsFailedToFetchHeader = []byte(`{"errors":[{"message":"failed to fetch","path":[`)
-	errorsFailedToFetchFooter = []byte(`]}]}`)
-)
-
-func (l *Loader) renderErrorsFailedToFetch(out *bytes.Buffer) error {
-	_, _ = out.Write(errorsFailedToFetchHeader)
-	for i := range l.path {
-		if i != 0 {
-			_, _ = out.Write(comma)
+func (l *Loader) renderErrorsFailedToFetch(res *result) error {
+	path := l.renderPath()
+	l.ctx.appendSubgraphError(errors.Wrap(res.err, fmt.Sprintf("failed to fetch from subgraph '%s' at path '%s'", res.subgraphName, path)))
+	if res.subgraphName == "" {
+		errorObject, err := l.data.AppendObject([]byte(fmt.Sprintf(`{"message":"Failed to fetch from Subgraph at path '%s'."}`, path)))
+		if err != nil {
+			return errors.WithStack(err)
 		}
-		_, _ = out.Write(quote)
-		_, _ = out.WriteString(l.path[i])
-		_, _ = out.Write(quote)
+		l.data.Nodes[l.errorsRoot].ArrayValues = append(l.data.Nodes[l.errorsRoot].ArrayValues, errorObject)
+	} else {
+		errorObject, err := l.data.AppendObject([]byte(fmt.Sprintf(`{"message":"Failed to fetch from Subgraph '%s' at path '%s'."}`, res.subgraphName, path)))
+		if err != nil {
+			return errors.WithStack(err)
+		}
+		l.data.Nodes[l.errorsRoot].ArrayValues = append(l.data.Nodes[l.errorsRoot].ArrayValues, errorObject)
 	}
-	_, _ = out.Write(errorsFailedToFetchFooter)
 	return nil
 }
 
 func (l *Loader) loadSingleFetch(ctx context.Context, fetch *SingleFetch, items []int, res *result) error {
+	res.init(fetch.PostProcessing, fetch.Info)
 	input := pool.BytesBuffer.Get()
 	defer pool.BytesBuffer.Put(input)
 	preparedInput := pool.BytesBuffer.Get()
@@ -515,15 +530,12 @@ func (l *Loader) loadSingleFetch(ctx context.Context, fetch *SingleFetch, items
 	if err != nil {
 		return l.renderErrorsInvalidInput(res.out)
 	}
-	err = l.executeSourceLoad(ctx, fetch.DataSource, preparedInput.Bytes(), res.out, fetch.Trace)
-	if err != nil {
-		return l.renderErrorsFailedToFetch(res.out)
-	}
-	res.postProcessing = fetch.PostProcessing
+	res.err = l.executeSourceLoad(ctx, fetch.DataSource, preparedInput.Bytes(), res.out, fetch.Trace)
 	return nil
 }
 
 func (l *Loader) loadEntityFetch(ctx context.Context, fetch *EntityFetch, items []int, res *result) error {
+	res.init(fetch.PostProcessing, fetch.Info)
 	itemData := pool.BytesBuffer.Get()
 	defer pool.BytesBuffer.Put(itemData)
 	preparedInput := pool.BytesBuffer.Get()
@@ -566,15 +578,15 @@ func (l *Loader) loadEntityFetch(ctx context.Context, fetch *EntityFetch, items
 	renderedItem := item.Bytes()
 	if bytes.Equal(renderedItem, null) {
 		// skip fetch if item is null
-		res.fetchAborted = true
+		res.fetchSkipped = true
 		if l.traceOptions.Enable {
 			fetch.Trace.LoadSkipped = true
 		}
 		return nil
 	}
 	if bytes.Equal(renderedItem, emptyObject) {
 		// skip fetch if item is empty
-		res.fetchAborted = true
+		res.fetchSkipped = true
 		if l.traceOptions.Enable {
 			fetch.Trace.LoadSkipped = true
 		}
@@ -590,17 +602,13 @@ func (l *Loader) loadEntityFetch(ctx context.Context, fetch *EntityFetch, items
 	if err != nil {
 		return errors.WithStack(err)
 	}
-
-	err = l.executeSourceLoad(ctx, fetch.DataSource, preparedInput.Bytes(), res.out, fetch.Trace)
-	if err != nil {
-		return errors.WithStack(err)
-	}
-	res.postProcessing = fetch.PostProcessing
+	res.err = l.executeSourceLoad(ctx, fetch.DataSource, preparedInput.Bytes(), res.out, fetch.Trace)
 	return nil
 }
 
 func (l *Loader) loadBatchEntityFetch(ctx context.Context, fetch *BatchEntityFetch, items []int, res *result) error {
-	res.postProcessing = fetch.PostProcessing
+	res.init(fetch.PostProcessing, fetch.Info)
+
 	if l.traceOptions.Enable {
 		fetch.Trace = &DataSourceLoadTrace{}
 		if !l.traceOptions.ExcludeRawInputData {
@@ -691,7 +699,7 @@ WithNextItem:
 
 	if len(itemHashes) == 0 {
 		// all items were skipped - discard fetch
-		res.fetchAborted = true
+		res.fetchSkipped = true
 		if l.traceOptions.Enable {
 			fetch.Trace.LoadSkipped = true
 		}
@@ -707,10 +715,7 @@ WithNextItem:
 	if err != nil {
 		return errors.WithStack(err)
 	}
-	err = l.executeSourceLoad(ctx, fetch.DataSource, preparedInput.Bytes(), res.out, fetch.Trace)
-	if err != nil {
-		return errors.WithStack(err)
-	}
+	res.err = l.executeSourceLoad(ctx, fetch.DataSource, preparedInput.Bytes(), res.out, fetch.Trace)
 	return nil
 }
 
@@ -916,13 +921,13 @@ func (l *Loader) executeSourceLoad(ctx context.Context, source DataSource, input
 			trace.DurationLoadPretty = time.Duration(trace.DurationLoadNano).String()
 		}
 	}
-	l.ctx.Stats.NumberOfFetches.Inc()
-	l.ctx.Stats.CombinedResponseSize.Add(int64(out.Len()))
 	if err != nil {
 		if l.traceOptions.Enable {
 			trace.LoadError = err.Error()
 		}
 		return errors.WithStack(err)
 	}
+	l.ctx.Stats.NumberOfFetches.Inc()
+	l.ctx.Stats.CombinedResponseSize.Add(int64(out.Len()))
 	return nil
 }

v2/pkg/engine/resolve/resolve_test.go

@@ -8,6 +8,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"net"
 	"net/http"
 	"sync"
 	"sync/atomic"
@@ -1682,6 +1683,69 @@ func TestResolver_ResolveGraphQLResponse(t *testing.T) {
 			},
 		}, Context{ctx: context.Background()}, `{"errors":[{"message":"errorMessage"}],"data":{"name":null}}`
 	}))
+	t.Run("fetch with returned err", testFn(true, func(t *testing.T, ctrl *gomock.Controller) (node *GraphQLResponse, ctx Context, expectedOutput string) {
+		mockDataSource := NewMockDataSource(ctrl)
+		mockDataSource.EXPECT().
+			Load(gomock.Any(), gomock.Any(), gomock.AssignableToTypeOf(&bytes.Buffer{})).
+			DoAndReturn(func(ctx context.Context, input []byte, w io.Writer) (err error) {
+				return &net.AddrError{}
+			})
+		return &GraphQLResponse{
+			Data: &Object{
+				Nullable: false,
+				Fetch: &SingleFetch{
+					FetchConfiguration: FetchConfiguration{
+						DataSource: mockDataSource,
+						PostProcessing: PostProcessingConfiguration{
+							SelectResponseErrorsPath: []string{"errors"},
+						},
+					},
+					Info: &FetchInfo{
+						DataSourceID: "Users",
+					},
+				},
+				Fields: []*Field{
+					{
+						Name: []byte("name"),
+						Value: &String{
+							Path:     []string{"name"},
+							Nullable: true,
+						},
+					},
+				},
+			},
+		}, Context{ctx: context.Background()}, `{"errors":[{"message":"Failed to fetch from Subgraph 'Users' at path 'query'."}],"data":null}`
+	}))
+	t.Run("fetch with returned err", testFn(true, func(t *testing.T, ctrl *gomock.Controller) (node *GraphQLResponse, ctx Context, expectedOutput string) {
+		mockDataSource := NewMockDataSource(ctrl)
+		mockDataSource.EXPECT().
+			Load(gomock.Any(), gomock.Any(), gomock.AssignableToTypeOf(&bytes.Buffer{})).
+			DoAndReturn(func(ctx context.Context, input []byte, w io.Writer) (err error) {
+				return &net.AddrError{}
+			})
+		return &GraphQLResponse{
+			Data: &Object{
+				Nullable: false,
+				Fetch: &SingleFetch{
+					FetchConfiguration: FetchConfiguration{
+						DataSource: mockDataSource,
+						PostProcessing: PostProcessingConfiguration{
+							SelectResponseErrorsPath: []string{"errors"},
+						},
+					},
+				},
+				Fields: []*Field{
+					{
+						Name: []byte("name"),
+						Value: &String{
+							Path:     []string{"name"},
+							Nullable: true,
+						},
+					},
+				},
+			},
+		}, Context{ctx: context.Background()}, `{"errors":[{"message":"Failed to fetch from Subgraph at path 'query'."}],"data":null}`
+	}))
 	t.Run("fetch with two Errors", testFn(true, func(t *testing.T, ctrl *gomock.Controller) (node *GraphQLResponse, ctx Context, expectedOutput string) {
 		mockDataSource := NewMockDataSource(ctrl)
 		mockDataSource.EXPECT().

v2/pkg/graphql/execution_engine_v2_test.go

@@ -668,7 +668,7 @@ func TestExecutionEngineV2_Execute(t *testing.T) {
 				},
 			},
 		},
-		expectedResponse: `{"errors":[{"message":"Cannot return null for non-nullable field 'Query.hero'.","path":["hero"]}],"data":null}`,
+		expectedResponse: `{"errors":[{"message":"invalid input","path":[]}],"data":null}`,
 	}))
 
 	t.Run("execute operation and apply input coercion for lists without variables", runWithoutError(ExecutionEngineV2TestCase{