admin: Set Config returns errSet and errMsg (#3822)

There is no way to see if a node encountered an error
when trying to set a new config set, this commit adds
a bool errSet field.

cmd/admin-handlers.go

@@ -719,8 +719,10 @@ func toAdminAPIErrCode(err error) APIErrorCode {
 // operation.
 type nodeSummary struct {
 	Name   string `json:"name"`
-	Err  string `json:"err"`
+	ErrSet bool   `json:"errSet"`
+	ErrMsg string `json:"errMsg"`
 }
+
 type setConfigResult struct {
 	NodeResults []nodeSummary `json:"nodeResults"`
 	Status      bool          `json:"status"`
@@ -734,7 +736,8 @@ func writeSetConfigResponse(w http.ResponseWriter, peers adminPeers, errs []erro
 	for i := range errs {
 		nodeResults = append(nodeResults, nodeSummary{
 			Name:   peers[i].addr,
-			Err:  fmt.Sprintf("%v", errs[i]),
+			ErrSet: errs[i] != nil,
+			ErrMsg: fmt.Sprintf("%v", errs[i]),
 		})
 
 	}

cmd/admin-handlers_test.go

@@ -1279,9 +1279,13 @@ func TestWriteSetConfigResponse(t *testing.T) {
 			if res.Name != testPeers[p].addr {
 				t.Errorf("Test %d: Expected node name %s but received %s", i+1, testPeers[p].addr, res.Name)
 			}
-			expectedErrStr := fmt.Sprintf("%v", test.errs[p])
+			expectedErrMsg := fmt.Sprintf("%v", test.errs[p])
-			if res.Err != expectedErrStr {
+			if res.ErrMsg != expectedErrMsg {
-				t.Errorf("Test %d: Expected error %s but received %s", i+1, expectedErrStr, res.Err)
+				t.Errorf("Test %d: Expected error %s but received %s", i+1, expectedErrMsg, res.ErrMsg)
+			}
+			expectedErrSet := test.errs[p] != nil
+			if res.ErrSet != expectedErrSet {
+				t.Errorf("Test %d: Expected ErrSet %v but received %v", i+1, expectedErrSet, res.ErrSet)
 			}
 		}
 	}

pkg/madmin/API.md

@@ -330,7 +330,8 @@ change to take effect.
 |---|---|---|
 |`st.Status`            | _bool_  | true if set-config succeeded, false otherwise. |
 |`st.NodeSummary.Name`  | _string_  | Network address of the node. |
-|`st.NodeSummary.Err`   | _string_ | String representation of the error (if any) on the node.|
+|`st.NodeSummary.ErrSet`   | _bool_ | Bool representation indicating if an error is encountered with the node.|
+|`st.NodeSummary.ErrMsg`   | _string_ | String representation of the error (if any) on the node.|
 
 
 __Example__

pkg/madmin/config-commands.go

@@ -34,7 +34,8 @@ const (
 // set-config on a node.
 type NodeSummary struct {
 	Name   string `json:"name"`
-	Err  string `json:"err"`
+	ErrSet bool   `json:"errSet"`
+	ErrMsg string `json:"errMsg"`
 }
 
 // SetConfigResult - represents detailed results of a set-config