From 1437ac42e3369ef59c56d6240a11e82e057fda0c Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Thu, 7 Jul 2022 14:39:51 +0100
Subject: [PATCH] Only register prometheus metrics if requested

---
 internal/caching/impl_ristretto.go | 30 ++++++++++++++++--------------
 1 file changed, 16 insertions(+), 14 deletions(-)

diff --git a/internal/caching/impl_ristretto.go b/internal/caching/impl_ristretto.go
index 0db4de5e6..9710cfa91 100644
--- a/internal/caching/impl_ristretto.go
+++ b/internal/caching/impl_ristretto.go
@@ -28,20 +28,22 @@ func MustCreateCache(maxCost config.DataUnit, enablePrometheus bool) *ristretto.
 	if err != nil {
 		panic(err)
 	}
-	promauto.NewGaugeFunc(prometheus.GaugeOpts{
-		Namespace: "dendrite",
-		Subsystem: "caching_ristretto",
-		Name:      "ratio",
-	}, func() float64 {
-		return float64(cache.Metrics.Ratio())
-	})
-	promauto.NewGaugeFunc(prometheus.GaugeOpts{
-		Namespace: "dendrite",
-		Subsystem: "caching_ristretto",
-		Name:      "cost",
-	}, func() float64 {
-		return float64(cache.Metrics.CostAdded() - cache.Metrics.CostEvicted())
-	})
+	if enablePrometheus {
+		promauto.NewGaugeFunc(prometheus.GaugeOpts{
+			Namespace: "dendrite",
+			Subsystem: "caching_ristretto",
+			Name:      "ratio",
+		}, func() float64 {
+			return float64(cache.Metrics.Ratio())
+		})
+		promauto.NewGaugeFunc(prometheus.GaugeOpts{
+			Namespace: "dendrite",
+			Subsystem: "caching_ristretto",
+			Name:      "cost",
+		}, func() float64 {
+			return float64(cache.Metrics.CostAdded() - cache.Metrics.CostEvicted())
+		})
+	}
 	return cache
 }