Make time parameter optional in v1 query API

If no time paramter is provided, the current server timestamp is used.

web/api/v1/api.go

@@ -54,15 +54,6 @@ type response struct {
 	Error     string      `json:"error,omitempty"`
 }
 
-// API can register a set of endpoints in a router and handle
-// them using the provided storage and query engine.
-type API struct {
-	Storage     local.Storage
-	QueryEngine *promql.Engine
-
-	context func(r *http.Request) context.Context
-}
-
 // Enables cross-site script calls.
 func setCORS(w http.ResponseWriter) {
 	w.Header().Set("Access-Control-Allow-Headers", "Accept, Authorization, Content-Type, Origin")
@@ -73,12 +64,28 @@ func setCORS(w http.ResponseWriter) {
 
 type apiFunc func(r *http.Request) (interface{}, *apiError)
 
+// API can register a set of endpoints in a router and handle
+// them using the provided storage and query engine.
+type API struct {
+	Storage     local.Storage
+	QueryEngine *promql.Engine
+
+	context func(r *http.Request) context.Context
+	now     func() model.Time
+}
+
+// NewAPI returns an initialized API type.
+func NewAPI(qe *promql.Engine, st local.Storage) *API {
+	return &API{
+		QueryEngine: qe,
+		Storage:     st,
+		context:     route.Context,
+		now:         model.Now,
+	}
+}
+
 // Register the API's endpoints in the given router.
 func (api *API) Register(r *route.Router) {
-	if api.context == nil {
-		api.context = route.Context
-	}
-
 	instr := func(name string, f apiFunc) http.HandlerFunc {
 		hf := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			setCORS(w)
@@ -108,10 +115,17 @@ type queryData struct {
 }
 
 func (api *API) query(r *http.Request) (interface{}, *apiError) {
-	ts, err := parseTime(r.FormValue("time"))
-	if err != nil {
-		return nil, &apiError{errorBadData, err}
+	var ts model.Time
+	if t := r.FormValue("time"); t != "" {
+		var err error
+		ts, err = parseTime(t)
+		if err != nil {
+			return nil, &apiError{errorBadData, err}
+		}
+	} else {
+		ts = api.now()
 	}
+
 	qry, err := api.QueryEngine.NewInstantQuery(r.FormValue("query"), ts)
 	if err != nil {
 		return nil, &apiError{errorBadData, err}

web/api/v1/api_test.go

@@ -35,9 +35,11 @@ func TestEndpoints(t *testing.T) {
 		t.Fatal(err)
 	}
 
+	now := model.Now()
 	api := &API{
 		Storage:     suite.Storage(),
 		QueryEngine: suite.QueryEngine(),
+		now:         func() model.Time { return now },
 	}
 
 	start := model.Time(0)
@@ -90,6 +92,19 @@ func TestEndpoints(t *testing.T) {
 				},
 			},
 		},
+		{
+			endpoint: api.query,
+			query: url.Values{
+				"query": []string{"0.333"},
+			},
+			response: &queryData{
+				ResultType: model.ValScalar,
+				Result: &model.Scalar{
+					Value:     0.333,
+					Timestamp: now,
+				},
+			},
+		},
 		{
 			endpoint: api.queryRange,
 			query: url.Values{
@@ -140,14 +155,6 @@ func TestEndpoints(t *testing.T) {
 			},
 			errType: errorBadData,
 		},
-		// Missing evaluation time.
-		{
-			endpoint: api.query,
-			query: url.Values{
-				"query": []string{"0.333"},
-			},
-			errType: errorBadData,
-		},
 		// Bad query expression.
 		{
 			endpoint: api.query,

web/web.go

@@ -138,10 +138,7 @@ func New(st local.Storage, qe *promql.Engine, rm *rules.Manager, status *Prometh
 		queryEngine: qe,
 		storage:     st,
 
-		apiV1: &v1.API{
-			QueryEngine: qe,
-			Storage:     st,
-		},
+		apiV1: v1.NewAPI(qe, st),
 		apiLegacy: &legacy.API{
 			QueryEngine: qe,
 			Storage:     st,