From 543bd0ea0c4f7f1d9f98c3af6ed4b23fbc49c64b Mon Sep 17 00:00:00 2001
From: Roman Khavronenko <hagen1778@gmail.com>
Date: Thu, 23 Dec 2021 11:53:50 +0200
Subject: [PATCH] vmselect: update /query_exemplars placeholder (#2000)

Grafana expects `data` in response to be a slice and logs an err
if it is not:
```
err="[]v1.ExemplarQueryResult: decode slice: expect [ or n, but found , error found in #0 byte of ...||..., bigger context ...||..."
```

https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1999
Signed-off-by: hagen1778 <roman@victoriametrics.com>
---
 app/vmselect/main.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/app/vmselect/main.go b/app/vmselect/main.go
index 406ee198af..366e1e9e77 100644
--- a/app/vmselect/main.go
+++ b/app/vmselect/main.go
@@ -423,7 +423,7 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 		// Return dumb placeholder for https://prometheus.io/docs/prometheus/latest/querying/api/#querying-exemplars
 		queryExemplarsRequests.Inc()
 		w.Header().Set("Content-Type", "application/json")
-		fmt.Fprintf(w, "%s", `{"status":"success","data":null}`)
+		fmt.Fprintf(w, "%s", `{"status":"success","data":[]}`)
 		return true
 	case "/api/v1/admin/tsdb/delete_series":
 		deleteRequests.Inc()