Fix/call response modifier plugin 597

proxy/plugin.go

@@ -15,7 +15,7 @@ import (
 
 // NewPluginMiddleware returns an endpoint middleware wrapped (if required) with the plugin middleware.
 // The plugin middleware will try to load all the required plugins from the register and execute them in order.
-// RequestModifiers are executed before passing the request to the next middlware. ResponseModifiers are executed
+// RequestModifiers are executed before passing the request to the next middleware. ResponseModifiers are executed
 // once the response is returned from the next middleware.
 func NewPluginMiddleware(logger logging.Logger, endpoint *config.EndpointConfig) Middleware {
 	cfg, ok := endpoint.ExtraConfig[plugin.Namespace].(map[string]interface{})
@@ -29,7 +29,7 @@ func NewPluginMiddleware(logger logging.Logger, endpoint *config.EndpointConfig)
 
 // NewBackendPluginMiddleware returns a backend middleware wrapped (if required) with the plugin middleware.
 // The plugin middleware will try to load all the required plugins from the register and execute them in order.
-// RequestModifiers are executed before passing the request to the next middlware. ResponseModifiers are executed
+// RequestModifiers are executed before passing the request to the next middleware. ResponseModifiers are executed
 // once the response is returned from the next middleware.
 func NewBackendPluginMiddleware(logger logging.Logger, remote *config.Backend) Middleware {
 	cfg, ok := remote.ExtraConfig[plugin.Namespace].(map[string]interface{})
@@ -88,12 +88,7 @@ func newPluginMiddleware(logger logging.Logger, tag, pattern string, cfg map[str
 
 		if totReqModifiers == 0 {
 			return func(ctx context.Context, r *Request) (*Response, error) {
-				resp, err := next[0](ctx, r)
-				if err != nil {
-					return resp, err
-				}
-
-				return executeResponseModifiers(respModifiers, resp)
+				return nextProxyWithResponseModifiers(ctx, r, next[0], respModifiers)
 			}
 		}
 
@@ -116,16 +111,22 @@ func newPluginMiddleware(logger logging.Logger, tag, pattern string, cfg map[str
 				return nil, err
 			}
 
-			resp, err := next[0](ctx, r)
-			if err != nil {
-				return resp, err
-			}
-
-			return executeResponseModifiers(respModifiers, resp)
+			return nextProxyWithResponseModifiers(ctx, r, next[0], respModifiers)
 		}
 	}
 }
 
+func nextProxyWithResponseModifiers(ctx context.Context, r *Request, next Proxy, respModifiers []func(interface{}) (interface{}, error)) (*Response, error) {
+	resp, err := next(ctx, r)
+	// merged responses of multiple backends will have a non nil resp if at least one of the backends responds
+	// successfully
+	if err != nil && resp == nil {
+		return resp, err
+	}
+
+	return executeResponseModifiers(respModifiers, resp)
+}
+
 func executeRequestModifiers(reqModifiers []func(interface{}) (interface{}, error), r *Request) (*Request, error) {
 	var tmp RequestWrapper
 	tmp = &requestWrapper{

proxy/plugin/tests/logger/main.go

@@ -25,7 +25,7 @@ func (r registerer) RegisterModifiers(f func(
 	appliesToResponse bool,
 )) {
 	f(string(r)+"-request", r.requestModifierFactory, true, false)
-	f(string(r)+"-response", r.reqsponseModifierFactory, false, true)
+	f(string(r)+"-response", r.responseModifierFactory, false, true)
 }
 
 func (registerer) RegisterLogger(in interface{}) {
@@ -47,7 +47,7 @@ func (registerer) requestModifierFactory(_ map[string]interface{}) func(interfac
 		return func(input interface{}) (interface{}, error) {
 			req, ok := input.(RequestWrapper)
 			if !ok {
-				return nil, unkownTypeErr
+				return nil, errUnknownType
 			}
 
 			return modifier(req), nil
@@ -58,7 +58,7 @@ func (registerer) requestModifierFactory(_ map[string]interface{}) func(interfac
 	return func(input interface{}) (interface{}, error) {
 		req, ok := input.(RequestWrapper)
 		if !ok {
-			return nil, unkownTypeErr
+			return nil, errUnknownType
 		}
 
 		r := modifier(req)
@@ -74,7 +74,7 @@ func (registerer) requestModifierFactory(_ map[string]interface{}) func(interfac
 	}
 }
 
-func (registerer) reqsponseModifierFactory(_ map[string]interface{}) func(interface{}) (interface{}, error) {
+func (registerer) responseModifierFactory(_ map[string]interface{}) func(interface{}) (interface{}, error) {
 	// check the cfg. If the modifier requires some configuration,
 	// it should be under the name of the plugin.
 	// ex: if this modifier required some A and B config params
@@ -96,7 +96,7 @@ func (registerer) reqsponseModifierFactory(_ map[string]interface{}) func(interf
 		return func(input interface{}) (interface{}, error) {
 			resp, ok := input.(ResponseWrapper)
 			if !ok {
-				return nil, unkownTypeErr
+				return nil, errUnknownType
 			}
 
 			fmt.Println("data:", resp.Data())
@@ -112,7 +112,7 @@ func (registerer) reqsponseModifierFactory(_ map[string]interface{}) func(interf
 	return func(input interface{}) (interface{}, error) {
 		resp, ok := input.(ResponseWrapper)
 		if !ok {
-			return nil, unkownTypeErr
+			return nil, errUnknownType
 		}
 
 		logger.Debug("data:", resp.Data())
@@ -136,7 +136,7 @@ func modifier(req RequestWrapper) requestWrapper {
 	}
 }
 
-var unkownTypeErr = errors.New("unknown request type")
+var errUnknownType = errors.New("unknown request type")
 
 type ResponseWrapper interface {
 	Data() map[string]interface{}

proxy/plugin_test.go

@@ -73,6 +73,59 @@ func TestNewPluginMiddleware_logger(t *testing.T) {
 	}
 }
 
+func TestNewPluginMiddleware_merge_error(t *testing.T) {
+	plugin.LoadWithLogger("./plugin/tests", ".so", plugin.RegisterModifier, logging.NoOp)
+
+	validator := func(ctx context.Context, r *Request) (*Response, error) {
+		return &Response{
+			Data:       map[string]interface{}{"foo": "bar"},
+			IsComplete: true,
+			Metadata: Metadata{
+				Headers:    map[string][]string{},
+				StatusCode: 0,
+			},
+		}, mergeError{errs: []error{fmt.Errorf("some backend error")}}
+	}
+
+	bknd := NewBackendPluginMiddleware(
+		logging.NoOp,
+		&config.Backend{
+			ExtraConfig: map[string]interface{}{
+				plugin.Namespace: map[string]interface{}{
+					"name": []interface{}{"lura-request-modifier-example-response"},
+				},
+			},
+		},
+	)(validator)
+
+	p := NewPluginMiddleware(
+		logging.NoOp,
+		&config.EndpointConfig{
+			ExtraConfig: map[string]interface{}{
+				plugin.Namespace: map[string]interface{}{
+					"name": []interface{}{
+						"lura-request-modifier-example-response",
+					},
+				},
+			},
+		},
+	)(bknd)
+
+	resp, err := p(context.Background(), &Request{Path: "/bar"})
+	if err != nil {
+		t.Error(err.Error())
+	}
+
+	if resp == nil {
+		t.Errorf("unexpected response: %v", resp)
+		return
+	}
+
+	if v, ok := resp.Data["foo"].(string); !ok || v != "bar" {
+		t.Errorf("unexpected foo value: %v", resp.Data["foo"])
+	}
+}
+
 func TestNewPluginMiddleware_error_request(t *testing.T) {
 	plugin.LoadWithLogger("./plugin/tests", ".so", plugin.RegisterModifier, logging.NoOp)