feat: status code derived fallback errors

v2/pkg/engine/resolve/context.go

@@ -141,8 +141,8 @@ func (c *Context) SubgraphErrors() error {
 	return c.subgraphErrors
 }
 
-func (c *Context) appendSubgraphError(err error) {
-	c.subgraphErrors = errors.Join(c.subgraphErrors, err)
+func (c *Context) appendSubgraphErrors(errs ...error) {
+	c.subgraphErrors = errors.Join(c.subgraphErrors, errors.Join(errs...))
 }
 
 type Request struct {

v2/pkg/engine/resolve/loader.go

@@ -7,7 +7,6 @@ import (
 	"encoding/json"
 	goerrors "errors"
 	"fmt"
-	"github.com/wundergraph/graphql-go-tools/v2/pkg/errorcodes"
 	"net/http"
 	"net/http/httptrace"
 	"slices"
@@ -16,6 +15,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/wundergraph/graphql-go-tools/v2/pkg/errorcodes"
+
 	"github.com/buger/jsonparser"
 	"github.com/cespare/xxhash/v2"
 	"github.com/pkg/errors"
@@ -559,6 +560,11 @@ func (l *Loader) mergeResult(fetchItem *FetchItem, res *result, items []*astjson
 	}
 	value, err := astjson.ParseBytesWithoutCache(res.out.Bytes())
 	if err != nil {
+		// Fall back to status code if parsing fails and non-2XX
+		if (res.statusCode > 0 && res.statusCode < 200) || res.statusCode >= 300 {
+			return l.renderErrorsStatusFallback(fetchItem, res, res.statusCode)
+		}
+
 		return l.renderErrorsFailedToFetch(fetchItem, res, invalidGraphQLResponse)
 	}
 
@@ -587,6 +593,14 @@ func (l *Loader) mergeResult(fetchItem *FetchItem, res *result, items []*astjson
 		value = value.Get(res.postProcessing.SelectResponseDataPath...)
 		// Check if the not set or null
 		if astjson.ValueIsNull(value) {
+			// When:
+			// - No errors or data are present
+			// - Status code is not within the 2XX range
+			// We can fall back to a status code based error
+			if !hasErrors && ((res.statusCode > 0 && res.statusCode < 200) || res.statusCode >= 300) {
+				return l.renderErrorsStatusFallback(fetchItem, res, res.statusCode)
+			}
+
 			// If we didn't get any data nor errors, we return an error because the response is invalid
 			// Returning an error here also avoids the need to walk over it later.
 			if !hasErrors && !l.resolvable.options.ApolloCompatibilitySuppressFetchErrors {
@@ -699,7 +713,7 @@ func (l *Loader) appendSubgraphError(res *result, fetchItem *FetchItem, value *a
 		subgraphError.AppendDownstreamError(&gErr)
 	}
 
-	l.ctx.appendSubgraphError(goerrors.Join(res.err, subgraphError))
+	l.ctx.appendSubgraphErrors(res.err, subgraphError)
 
 	return nil
 }
@@ -1012,7 +1026,7 @@ func (l *Loader) addApolloRouterCompatibilityError(res *result) error {
 }
 
 func (l *Loader) renderErrorsFailedToFetch(fetchItem *FetchItem, res *result, reason string) error {
-	l.ctx.appendSubgraphError(goerrors.Join(res.err, NewSubgraphError(res.ds, fetchItem.ResponsePath, reason, res.statusCode)))
+	l.ctx.appendSubgraphErrors(res.err, NewSubgraphError(res.ds, fetchItem.ResponsePath, reason, res.statusCode))
 	errorObject, err := astjson.ParseWithoutCache(l.renderSubgraphBaseError(res.ds, fetchItem.ResponsePath, reason))
 	if err != nil {
 		return err
@@ -1022,6 +1036,25 @@ func (l *Loader) renderErrorsFailedToFetch(fetchItem *FetchItem, res *result, re
 	return nil
 }
 
+func (l *Loader) renderErrorsStatusFallback(fetchItem *FetchItem, res *result, statusCode int) error {
+	reason := fmt.Sprintf("%d", statusCode)
+	if statusText := http.StatusText(statusCode); statusText != "" {
+		reason += fmt.Sprintf(": %s", statusText)
+	}
+
+	l.ctx.appendSubgraphErrors(res.err, NewSubgraphError(res.ds, fetchItem.ResponsePath, reason, res.statusCode))
+
+	errorObject, err := astjson.ParseWithoutCache(fmt.Sprintf(`{"message":"%s"}`, reason))
+	if err != nil {
+		return err
+	}
+
+	l.setSubgraphStatusCode([]*astjson.Value{errorObject}, res.statusCode)
+
+	astjson.AppendToArray(l.resolvable.errors, errorObject)
+	return nil
+}
+
 func (l *Loader) renderSubgraphBaseError(ds DataSourceInfo, path, reason string) string {
 	pathPart := l.renderAtPathErrorPart(path)
 	if ds.Name == "" {
@@ -1038,7 +1071,7 @@ func (l *Loader) renderSubgraphBaseError(ds DataSourceInfo, path, reason string)
 
 func (l *Loader) renderAuthorizationRejectedErrors(fetchItem *FetchItem, res *result) error {
 	for i := range res.authorizationRejectedReasons {
-		l.ctx.appendSubgraphError(goerrors.Join(res.err, NewSubgraphError(res.ds, fetchItem.ResponsePath, res.authorizationRejectedReasons[i], res.statusCode)))
+		l.ctx.appendSubgraphErrors(res.err, NewSubgraphError(res.ds, fetchItem.ResponsePath, res.authorizationRejectedReasons[i], res.statusCode))
 	}
 	pathPart := l.renderAtPathErrorPart(fetchItem.ResponsePath)
 	extensionErrorCode := fmt.Sprintf(`"extensions":{"code":"%s"}`, errorcodes.UnauthorizedFieldOrType)
@@ -1079,7 +1112,7 @@ func (l *Loader) renderAuthorizationRejectedErrors(fetchItem *FetchItem, res *re
 }
 
 func (l *Loader) renderRateLimitRejectedErrors(fetchItem *FetchItem, res *result) error {
-	l.ctx.appendSubgraphError(goerrors.Join(res.err, NewRateLimitError(res.ds.Name, fetchItem.ResponsePath, res.rateLimitRejectedReason)))
+	l.ctx.appendSubgraphErrors(res.err, NewRateLimitError(res.ds.Name, fetchItem.ResponsePath, res.rateLimitRejectedReason))
 	pathPart := l.renderAtPathErrorPart(fetchItem.ResponsePath)
 	var (
 		err         error

v2/pkg/engine/resolve/resolvable.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
-	goerrors "errors"
 	"fmt"
 	"io"
 	"strconv"
@@ -760,8 +759,8 @@ func (r *Resolvable) addRejectFieldError(reason string, ds DataSourceInfo, field
 	} else {
 		errorMessage = fmt.Sprintf("Unauthorized to load field '%s', Reason: %s.", fieldPath, reason)
 	}
-	r.ctx.appendSubgraphError(goerrors.Join(errors.New(errorMessage),
-		NewSubgraphError(ds, fieldPath, reason, 0)))
+	r.ctx.appendSubgraphErrors(errors.New(errorMessage),
+		NewSubgraphError(ds, fieldPath, reason, 0))
 	fastjsonext.AppendErrorWithExtensionsCodeToArray(r.astjsonArena, r.errors, errorMessage, errorcodes.UnauthorizedFieldOrType, r.path)
 	r.popNodePathElement(nodePath)
 }