to be merged: log kms error from json message

Author: urykhy

file_writer.go

@@ -86,6 +86,7 @@ func (c *Client) CreateFile(name string, replication int, blockSize int64, perm
 	if createResp.GetFs().GetFileEncryptionInfo() != nil {
 		enc, err = c.kmsGetKey(createResp.GetFs().GetFileEncryptionInfo())
 		if err != nil {
+			c.Remove(name)
 			return nil, &os.PathError{"create", name, err}
 		}
 	}

kms.go

@@ -160,7 +160,20 @@ func (c *Client) kmsDecrypt(url string, requestBody []byte) ([]byte, error) {
 	}
 
 	if statusCode != 200 {
-		return nil, fmt.Errorf("unexpected response code from KMS: %v", statusCode)
+		// On error, kms respond with error message in JSON object.
+		type Exception struct {
+			RemoteException struct {
+				Message string `json:"message"`
+			}
+		}
+		var kmsException Exception
+		if err = json.Unmarshal(responseBody, &kmsException); err == nil && kmsException.RemoteException.Message != "" {
+			errorMessage := kmsException.RemoteException.Message
+			err = errors.New(errorMessage)
+		} else {
+			err = fmt.Errorf("unexpected response code from KMS: %v", statusCode)
+		}
+		return nil, err
 	}
 
 	type KmsRespose struct {