*: Use exponential buckets for histogram metrics (thanos-io#1545)

* Use exponential buckets for compactor histogram metrics

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Update buckets

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Adjust histogram buckets

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Adjust store gate bucket

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Adjust http duration buckets

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>
Signed-off-by: Aleksey Sin <asin@ozon.ru>

cmd/thanos/query.go

@@ -168,9 +168,7 @@ func registerQuery(m map[string]setupFunc, app *kingpin.Application) {
 func storeClientGRPCOpts(logger log.Logger, reg *prometheus.Registry, tracer opentracing.Tracer, secure bool, cert, key, caCert, serverName string) ([]grpc.DialOption, error) {
 	grpcMets := grpc_prometheus.NewClientMetrics()
 	grpcMets.EnableClientHandlingTimeHistogram(
-		grpc_prometheus.WithHistogramBuckets([]float64{
-			0.001, 0.01, 0.05, 0.1, 0.2, 0.4, 0.8, 1.6, 3.2, 6.4,
-		}),
+		grpc_prometheus.WithHistogramBuckets(prometheus.ExponentialBuckets(0.001, 2, 15)),
 	)
 	dialOpts := []grpc.DialOption{
 		// We want to make sure that we can receive huge gRPC messages from storeAPI.