Add failing RPC method to api error response

This makes debugging api clients such as CSI
debugging relatively easy.

Author: venkatsc

quobyte/rpc_client.go

@@ -15,7 +15,8 @@ import (
 )
 
 const (
-	emptyResponse string = "Empty result and no error occurred"
+	emptyResponse      string = "Empty result and no error occurred"
+	errorMessageFormat string = "method: %s error message: %s"
 )
 
 var mux sync.Mutex
@@ -64,7 +65,7 @@ func encodeRequest(method string, params interface{}) ([]byte, error) {
 	})
 }
 
-func decodeResponse(ioReader io.Reader, reply interface{}) error {
+func decodeResponse(method string, ioReader io.Reader, reply interface{}) error {
 	var resp response
 	if err := json.NewDecoder(ioReader).Decode(&resp); err != nil {
 		return err
@@ -77,20 +78,20 @@ func decodeResponse(ioReader io.Reader, reply interface{}) error {
 		}
 
 		if rpcErr.Message != "" {
-			return errors.New(rpcErr.Message)
+			return fmt.Errorf(errorMessageFormat, method, rpcErr.Message)
 		}
 
 		respError := rpcErr.decodeErrorCode()
 		if respError != "" {
-			return errors.New(respError)
+			return fmt.Errorf(errorMessageFormat, method, respError)
 		}
 	}
 
 	if resp.Result != nil && reply != nil {
 		return json.Unmarshal(*resp.Result, reply)
 	}
 
-	return errors.New(emptyResponse)
+	return fmt.Errorf(errorMessageFormat, method, emptyResponse)
 }
 
 func (client QuobyteClient) sendRequest(method string, request interface{}, response interface{}) error {
@@ -157,6 +158,6 @@ func (client QuobyteClient) sendRequest(method string, request interface{}, resp
 			return fmt.Errorf("JsonRPC failed with error (error code: %d) %s",
 				resp.StatusCode, string(body))
 		}
-		return decodeResponse(resp.Body, &response)
+		return decodeResponse(method, resp.Body, &response)
 	}
 }

quobyte/rpc_client_test.go

@@ -3,6 +3,7 @@ package quobyte
 import (
 	"bytes"
 	"encoding/json"
+	"fmt"
 	"net/http"
 	"net/http/httptest"
 	"reflect"
@@ -62,7 +63,7 @@ func TestSuccessfullDecodeResponse(t *testing.T) {
 	res, _ := json.Marshal(expectedResult)
 
 	var resp CreateVolumeResponse
-	err := decodeResponse(bytes.NewReader(res), &resp)
+	err := decodeResponse("", bytes.NewReader(res), &resp)
 	if err != nil {
 		t.Log(err)
 		t.Fail()
@@ -75,7 +76,8 @@ func TestSuccessfullDecodeResponse(t *testing.T) {
 }
 
 func TestSuccessfullDecodeResponseWithErrorMessage(t *testing.T) {
-	errorMessage := "ERROR_CODE_INVALID_REQUEST"
+	method := "testMethod"
+	errorMessage := fmt.Sprintf(errorMessageFormat, method, "ERROR_CODE_INVALID_REQUEST")
 	var byt json.RawMessage
 	byt, _ = json.Marshal(&rpcError{
 		Code:    -32600,
@@ -91,7 +93,7 @@ func TestSuccessfullDecodeResponseWithErrorMessage(t *testing.T) {
 	res, _ := json.Marshal(expectedResult)
 
 	var resp CreateVolumeResponse
-	err := decodeResponse(bytes.NewReader(res), &resp)
+	err := decodeResponse(method, bytes.NewReader(res), &resp)
 	if err == nil {
 		t.Log("No error occurred")
 		t.Fail()
@@ -104,7 +106,8 @@ func TestSuccessfullDecodeResponseWithErrorMessage(t *testing.T) {
 }
 
 func TestSuccesfullDecodeResponseWithErrorCode(t *testing.T) {
-	errorMessage := "ERROR_CODE_INVALID_REQUEST"
+	method := "testMethod"
+	errorMessage := fmt.Sprintf(errorMessageFormat, method, "ERROR_CODE_INVALID_REQUEST")
 	var byt json.RawMessage
 	byt, _ = json.Marshal(&rpcError{
 		Code: -32600,
@@ -119,7 +122,7 @@ func TestSuccesfullDecodeResponseWithErrorCode(t *testing.T) {
 	res, _ := json.Marshal(expectedResult)
 
 	var resp CreateVolumeResponse
-	err := decodeResponse(bytes.NewReader(res), &resp)
+	err := decodeResponse(method, bytes.NewReader(res), &resp)
 	if err == nil {
 		t.Log("No error occurred")
 		t.Fail()
@@ -132,6 +135,8 @@ func TestSuccesfullDecodeResponseWithErrorCode(t *testing.T) {
 }
 
 func TestBadDecodeResponse(t *testing.T) {
+	method := "testMethod"
+	expectedError := fmt.Sprintf(errorMessageFormat, method, emptyResponse)
 	expectedResult := &response{
 		ID:      "0",
 		Version: "2.0",
@@ -140,14 +145,14 @@ func TestBadDecodeResponse(t *testing.T) {
 	res, _ := json.Marshal(expectedResult)
 
 	var resp CreateVolumeResponse
-	err := decodeResponse(bytes.NewReader(res), &resp)
+	err := decodeResponse(method, bytes.NewReader(res), &resp)
 	if err == nil {
 		t.Log("No error occurred")
 		t.Fail()
 	}
 
-	if emptyResponse != err.Error() {
-		t.Logf("Expected: %s got %s\n", emptyResponse, err.Error())
+	if expectedError != err.Error() {
+		t.Logf("Expected: %s got %s\n", expectedError, err.Error())
 		t.Fail()
 	}
 }