K8s: Add basic query service (#80325)

pkg/api/api.go

@@ -515,7 +515,7 @@ func (hs *HTTPServer) registerRoutes() {
 
 		// metrics
 		// DataSource w/ expressions
-		apiRoute.Post("/ds/query", requestmeta.SetSLOGroup(requestmeta.SLOGroupHighSlow), authorize(ac.EvalPermission(datasources.ActionQuery)), routing.Wrap(hs.QueryMetricsV2))
+		apiRoute.Post("/ds/query", requestmeta.SetSLOGroup(requestmeta.SLOGroupHighSlow), authorize(ac.EvalPermission(datasources.ActionQuery)), hs.getDSQueryEndpoint())
 
 		apiRoute.Group("/alerts", func(alertsRoute routing.RouteRegister) {
 			alertsRoute.Post("/test", routing.Wrap(hs.AlertTest))

pkg/api/metrics.go

@@ -10,10 +10,14 @@ import (
 
 	"github.com/grafana/grafana/pkg/api/dtos"
 	"github.com/grafana/grafana/pkg/api/response"
+	"github.com/grafana/grafana/pkg/api/routing"
+	"github.com/grafana/grafana/pkg/infra/appcontext"
 	"github.com/grafana/grafana/pkg/middleware/requestmeta"
 	contextmodel "github.com/grafana/grafana/pkg/services/contexthandler/model"
 	"github.com/grafana/grafana/pkg/services/datasources"
 	"github.com/grafana/grafana/pkg/services/featuremgmt"
+	"github.com/grafana/grafana/pkg/services/grafana-apiserver/endpoints/request"
+	"github.com/grafana/grafana/pkg/util/errutil/errhttp"
 	"github.com/grafana/grafana/pkg/web"
 )
 
@@ -33,6 +37,26 @@ func (hs *HTTPServer) handleQueryMetricsError(err error) *response.NormalRespons
 	return response.ErrOrFallback(http.StatusInternalServerError, "Query data error", err)
 }
 
+// metrics.go
+func (hs *HTTPServer) getDSQueryEndpoint() web.Handler {
+	if hs.Features.IsEnabledGlobally(featuremgmt.FlagKubernetesQueryServiceRewrite) {
+		// DEV ONLY FEATURE FLAG!
+		// rewrite requests from /ds/query to the new query service
+		namespaceMapper := request.GetNamespaceMapper(hs.Cfg)
+		return func(w http.ResponseWriter, r *http.Request) {
+			user, err := appcontext.User(r.Context())
+			if err != nil || user == nil {
+				errhttp.Write(r.Context(), fmt.Errorf("no user"), w)
+				return
+			}
+			r.URL.Path = "/apis/query.grafana.app/v0alpha1/namespaces/" + namespaceMapper(user.OrgID) + "/query"
+			hs.clientConfigProvider.DirectlyServeHTTP(w, r)
+		}
+	}
+
+	return routing.Wrap(hs.QueryMetricsV2)
+}
+
 // QueryMetricsV2 returns query metrics.
 // swagger:route POST /ds/query ds queryMetricsWithExpressions
 //