Alerting: unified alerting frontend (#32708)

pkg/services/ngalert/api/util.go

@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"regexp"
 	"strconv"
+	"strings"
 
 	"github.com/go-openapi/strfmt"
 	apimodels "github.com/grafana/alerting-api/pkg/api"
@@ -45,7 +46,7 @@ func backendType(ctx *models.ReqContext, cache datasources.CacheService) (apimod
 			switch ds.Type {
 			case "loki", "prometheus":
 				return apimodels.LoTexRulerBackend, nil
-			case "grafana-alertmanager-datasource":
+			case "alertmanager":
 				return apimodels.AlertmanagerBackend, nil
 			default:
 				return 0, fmt.Errorf("unexpected backend type (%v)", ds.Type)
@@ -94,7 +95,19 @@ func (p *AlertingProxy) withReq(
 
 	status := resp.Status()
 	if status >= 400 {
-		return response.Error(status, string(resp.Body()), nil)
+		errMessage := string(resp.Body())
+		// if Content-Type is application/json
+		// and it is successfully decoded and contains a message
+		// return this as response error message
+		if strings.HasPrefix(resp.Header().Get("Content-Type"), "application/json") {
+			var m map[string]interface{}
+			if err := json.Unmarshal(resp.Body(), &m); err == nil {
+				if message, ok := m["message"]; ok {
+					errMessage = message.(string)
+				}
+			}
+		}
+		return response.Error(status, errMessage, nil)
 	}
 
 	t, err := extractor(resp.Body())