Alerting: New API endpoint GET /api/v1/ngalert (#55134)

* declare new endpoint /api/v1/ngalert
* add authorization for new path
* add request handler for the new path

pkg/services/ngalert/api/tooling/definitions/admin.go

@@ -4,6 +4,16 @@ import (
 	v1 "github.com/prometheus/client_golang/api/prometheus/v1"
 )
 
+// swagger:route GET /api/v1/ngalert configuration RouteGetStatus
+//
+//  Get the status of the alerting engine
+//
+//     Produces:
+//     - application/json
+//
+//     Responses:
+//		 200: AlertingStatus
+
 // swagger:route GET /api/v1/ngalert/alertmanagers configuration RouteGetAlertmanagers
 //
 //  Get the discovered and dropped Alertmanagers of the user's organization based on the specified configuration.
@@ -81,3 +91,8 @@ type GettableAlertmanagers struct {
 	Status string                 `json:"status"`
 	Data   v1.AlertManagersResult `json:"data"`
 }
+
+// swagger:model
+type AlertingStatus struct {
+	AlertmanagersChoice AlertmanagersChoice `json:"alertmanagersChoice"`
+}