Adjust buckets in apiserver request latency metrics

staging/src/k8s.io/apiserver/pkg/endpoints/metrics/metrics.go

@@ -72,8 +72,11 @@ var (
 		prometheus.HistogramOpts{
 			Name: "apiserver_request_latency_seconds",
 			Help: "Response latency distribution in seconds for each verb, group, version, resource, subresource, scope and component.",
-			// Use buckets ranging from 125 ms to 8 seconds.
-			Buckets: prometheus.ExponentialBuckets(0.125, 2.0, 7),
+			// This metric is used for verifying api call latencies SLO,
+			// as well as tracking regressions in this aspects.
+			// Thus we customize buckets significantly, to empower both usecases.
+			Buckets: []float64{0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0,
+				1.25, 1.5, 1.75, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, 50, 60},
 		},
 		[]string{"verb", "group", "version", "resource", "subresource", "scope", "component"},
 	)