filter param

Author: lomik

README.md

@@ -68,7 +68,7 @@ bgcolor = "black"
 ## URI Parameters
 * **g0.expr**, **g1.expr**, ..., **gN.expr** - prometheus queries
 * **g0.legend**, **g1.legend**, ..., **gN.legend** - custom legend [template](https://golang.org/pkg/text/template/). Tag values can be printed with {{.tagname}} instruction
-* **query** - alias for g0.expr
+* **gN.filter[labelName]=labelValue** - display only series with corresponding label values
 * **timeout** - optional custom query timeout
 * **pixelRatio** - device pixel ratio
 * **template** - template name from config

pkg/hander.go

@@ -206,10 +206,18 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			return
 		}
 
+	SeriesLoop:
 		for _, r := range promRes.Data.Result {
 			if len(r.Values) < 1 {
 				continue
 			}
+			// check filter
+			for labelName, filterValue := range graphData.Filter {
+				if labelValue, exists := r.Metric[labelName]; !exists || filterValue != labelValue {
+					continue SeriesLoop
+				}
+			}
+
 			step := int64(1)
 			if len(r.Values) > 1 {
 				step = r.Values[1].Timestamp - r.Values[0].Timestamp