Alerting: Fix error message in ngalert when notifications cannot be s…

…ent to alertmanager (#40158)

(cherry picked from commit 8318e45)

pkg/services/ngalert/notifier/channels/alertmanager.go

@@ -79,22 +79,26 @@ func (n *AlertmanagerNotifier) Notify(ctx context.Context, as ...*types.Alert) (
 		return false, err
 	}
 
-	errCnt := 0
+	var (
+		lastErr error
+		numErrs int
+	)
 	for _, u := range n.urls {
 		if _, err := sendHTTPRequest(ctx, u, httpCfg{
 			user:     n.basicAuthUser,
 			password: n.basicAuthPassword,
 			body:     body,
 		}, n.logger); err != nil {
 			n.logger.Warn("Failed to send to Alertmanager", "error", err, "alertmanager", n.Name, "url", u.String())
-			errCnt++
+			lastErr = err
+			numErrs++
 		}
 	}
 
-	if errCnt == len(n.urls) {
+	if numErrs == len(n.urls) {
 		// All attempts to send alerts have failed
 		n.logger.Warn("All attempts to send to Alertmanager failed", "alertmanager", n.Name)
-		return false, fmt.Errorf("failed to send alert to Alertmanager")
+		return false, fmt.Errorf("failed to send alert to Alertmanager: %w", lastErr)
 	}
 
 	return true, nil

pkg/services/ngalert/notifier/channels/alertmanager_test.go

@@ -3,6 +3,7 @@ package channels
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"net/url"
 	"testing"
 
@@ -15,19 +16,69 @@ import (
 	"github.com/grafana/grafana/pkg/infra/log"
 )
 
-func TestAlertmanagerNotifier(t *testing.T) {
+func TestNewAlertmanagerNotifier(t *testing.T) {
 	tmpl := templateForTests(t)
 
 	externalURL, err := url.Parse("http://localhost")
 	require.NoError(t, err)
 	tmpl.ExternalURL = externalURL
 
 	cases := []struct {
-		name         string
-		settings     string
-		alerts       []*types.Alert
-		expInitError string
-		receiverName string
+		name              string
+		settings          string
+		alerts            []*types.Alert
+		expectedInitError string
+		receiverName      string
+	}{
+		{
+			name:              "Error in initing: missing URL",
+			settings:          `{}`,
+			expectedInitError: `failed to validate receiver of type "alertmanager": could not find url property in settings`,
+		}, {
+			name: "Error in initing: invalid URL",
+			settings: `{
+				"url": "://alertmanager.com"
+			}`,
+			expectedInitError: `failed to validate receiver "Alertmanager" of type "alertmanager": invalid url property in settings: parse "://alertmanager.com/api/v1/alerts": missing protocol scheme`,
+			receiverName:      "Alertmanager",
+		},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			settingsJSON, err := simplejson.NewJson([]byte(c.settings))
+			require.NoError(t, err)
+
+			m := &NotificationChannelConfig{
+				Name:     c.receiverName,
+				Type:     "alertmanager",
+				Settings: settingsJSON,
+			}
+
+			sn, err := NewAlertmanagerNotifier(m, tmpl)
+			if c.expectedInitError != "" {
+				require.Equal(t, c.expectedInitError, err.Error())
+				return
+			}
+			require.NoError(t, err)
+			require.NotNil(t, sn)
+		})
+	}
+}
+
+func TestAlertmanagerNotifier_Notify(t *testing.T) {
+	tmpl := templateForTests(t)
+
+	externalURL, err := url.Parse("http://localhost")
+	require.NoError(t, err)
+	tmpl.ExternalURL = externalURL
+
+	cases := []struct {
+		name                 string
+		settings             string
+		alerts               []*types.Alert
+		expectedError        string
+		sendHTTPRequestError error
+		receiverName         string
 	}{
 		{
 			name:     "Default config with one alert",
@@ -54,16 +105,21 @@ func TestAlertmanagerNotifier(t *testing.T) {
 				},
 			},
 		}, {
-			name:         "Error in initing: missing URL",
-			settings:     `{}`,
-			expInitError: `failed to validate receiver of type "alertmanager": could not find url property in settings`,
-		}, {
-			name: "Error in initing: invalid URL",
+			name: "Error sending to Alertmanager",
 			settings: `{
-				"url": "://alertmanager.com"
+				"url": "https://alertmanager.com"
 			}`,
-			expInitError: `failed to validate receiver "Alertmanager" of type "alertmanager": invalid url property in settings: parse "://alertmanager.com/api/v1/alerts": missing protocol scheme`,
-			receiverName: "Alertmanager",
+			alerts: []*types.Alert{
+				{
+					Alert: model.Alert{
+						Labels:      model.LabelSet{"__alert_rule_uid__": "rule uid", "alertname": "alert1", "lbl1": "val1"},
+						Annotations: model.LabelSet{"ann1": "annv1"},
+					},
+				},
+			},
+			expectedError:        "failed to send alert to Alertmanager: expected error",
+			sendHTTPRequestError: errors.New("expected error"),
+			receiverName:         "Alertmanager",
 		},
 	}
 	for _, c := range cases {
@@ -78,10 +134,6 @@ func TestAlertmanagerNotifier(t *testing.T) {
 			}
 
 			sn, err := NewAlertmanagerNotifier(m, tmpl)
-			if c.expInitError != "" {
-				require.Equal(t, c.expInitError, err.Error())
-				return
-			}
 			require.NoError(t, err)
 
 			var body []byte
@@ -91,19 +143,23 @@ func TestAlertmanagerNotifier(t *testing.T) {
 			})
 			sendHTTPRequest = func(ctx context.Context, url *url.URL, cfg httpCfg, logger log.Logger) ([]byte, error) {
 				body = cfg.body
-				return nil, nil
+				return nil, c.sendHTTPRequestError
 			}
 
 			ctx := notify.WithGroupKey(context.Background(), "alertname")
 			ctx = notify.WithGroupLabels(ctx, model.LabelSet{"alertname": ""})
 			ok, err := sn.Notify(ctx, c.alerts...)
-			require.NoError(t, err)
-			require.True(t, ok)
 
-			expBody, err := json.Marshal(c.alerts)
-			require.NoError(t, err)
-
-			require.JSONEq(t, string(expBody), string(body))
+			if c.sendHTTPRequestError != nil {
+				require.EqualError(t, err, c.expectedError)
+				require.False(t, ok)
+			} else {
+				require.NoError(t, err)
+				require.True(t, ok)
+				expBody, err := json.Marshal(c.alerts)
+				require.NoError(t, err)
+				require.JSONEq(t, string(expBody), string(body))
+			}
 		})
 	}
 }