Add show plan endpoint

api/graphite.go

@@ -1201,3 +1201,55 @@ func (s *Server) graphiteTagDelSeries(ctx *middleware.Context, request models.Gr
 
 	response.Write(ctx, response.NewJson(200, res, ""))
 }
+
+// showPlan attempts to create a Plan given a /render target query.
+// If the Plan creation is successful it returns 200, JSON marshaling of Plan.
+// Otherwise, it returns 400, error details.
+// This is needed to determine if a query cannot be resolved in localOnly mode.
+func (s *Server) showPlan(ctx *middleware.Context, request models.GraphiteRender) {
+	// note: the model is already validated to assure at least one of them has len >0
+	if len(request.Targets) == 0 {
+		request.Targets = request.TargetsRails
+	}
+
+	now := time.Now()
+	defaultFrom := uint32(now.Add(-time.Duration(24) * time.Hour).Unix())
+	defaultTo := uint32(now.Unix())
+	fromUnix, toUnix, err := getFromTo(request.FromTo, now, defaultFrom, defaultTo)
+	if err != nil {
+		response.Write(ctx, response.NewError(http.StatusBadRequest, err.Error()))
+		return
+	}
+	if fromUnix >= toUnix {
+		response.Write(ctx, response.NewError(http.StatusBadRequest, InvalidTimeRangeErr.Error()))
+		return
+	}
+
+	// render API is modeled after graphite, so from exclusive, to inclusive.
+	// in MT, from is inclusive, to is exclusive (which is akin to slice syntax)
+	// so we must adjust
+	fromUnix += 1
+	toUnix += 1
+
+	exprs, err := expr.ParseMany(request.Targets)
+	if err != nil {
+		response.Write(ctx, response.NewError(http.StatusBadRequest, err.Error()))
+		return
+	}
+
+	stable := request.Process == "stable"
+	mdp := request.MaxDataPoints
+
+	plan, err := expr.NewPlan(exprs, fromUnix, toUnix, mdp, stable, nil)
+	if err != nil {
+		response.Write(ctx, response.NewError(http.StatusBadRequest, err.Error()))
+		return
+	}
+	switch request.Format {
+	case "json":
+		response.Write(ctx, response.NewJson(200, plan, ""))
+	default:
+		response.Write(ctx, response.NewError(http.StatusBadRequest, "Unsupported response format requested: "+request.Format))
+	}
+	plan.Clean()
+}

api/routes.go

@@ -53,6 +53,8 @@ func (s *Server) RegisterRoutes() {
 		ctx.Write(nil)
 	})
 
+	r.Combo("/showplan", cBody, withOrg, ready, bind(models.GraphiteRender{})).Get(s.showPlan).Post(s.showPlan)
+
 	// Graphite endpoints
 	r.Combo("/render", cBody, withOrg, ready, bind(models.GraphiteRender{})).Get(s.renderMetrics).Post(s.renderMetrics)
 	r.Combo("/metrics/find", withOrg, ready, bind(models.GraphiteFind{})).Get(s.metricsFind).Post(s.metricsFind)