From 69467af6f3cb1e7a061cbb185cefff8611553864 Mon Sep 17 00:00:00 2001
From: Mahmoud Gaballah <mahmoud.gaballah@zalando.de>
Date: Wed, 18 Jan 2023 10:22:54 +0100
Subject: [PATCH] configuerable histogram buckets

---
 internal/kubenurse/server.go               | 27 +++++++++++++++++++++-
 internal/servicecheck/servicecheck.go      |  4 ++--
 internal/servicecheck/servicecheck_test.go |  2 +-
 3 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/internal/kubenurse/server.go b/internal/kubenurse/server.go
index 5bb586fb..d4a075aa 100644
--- a/internal/kubenurse/server.go
+++ b/internal/kubenurse/server.go
@@ -6,6 +6,8 @@ import (
 	"fmt"
 	"net/http"
 	"os"
+	"strconv"
+	"strings"
 	"sync"
 	"time"
 
@@ -101,8 +103,31 @@ func New(ctx context.Context, k8s kubernetes.Interface) (*Server, error) {
 		return nil, fmt.Errorf("create k8s discovery client: %w", err)
 	}
 
+	var histogramBuckets []float64
+
+	if bucketsString := os.Getenv("KUBENURSE_HISTOGRAM_BUCKETS"); bucketsString != "" {
+		var buckets []float64
+
+		for _, bucketStr := range strings.Split(bucketsString, ",") {
+			bucket, err := strconv.ParseFloat(bucketStr, 64)
+
+			if err != nil {
+				buckets = nil
+				break
+			}
+
+			buckets = append(buckets, bucket)
+		}
+
+		histogramBuckets = buckets
+	}
+
+	if histogramBuckets == nil {
+		histogramBuckets = prometheus.DefBuckets
+	}
+
 	// setup checker
-	chk, err := servicecheck.New(ctx, discovery, promRegistry, server.allowUnschedulable, 3*time.Second)
+	chk, err := servicecheck.New(ctx, discovery, promRegistry, server.allowUnschedulable, 3*time.Second, histogramBuckets)
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/servicecheck/servicecheck.go b/internal/servicecheck/servicecheck.go
index 77d569be..a95489f1 100644
--- a/internal/servicecheck/servicecheck.go
+++ b/internal/servicecheck/servicecheck.go
@@ -23,7 +23,7 @@ const (
 // New configures the checker with a httpClient and a cache timeout for check
 // results. Other parameters of the Checker struct need to be configured separately.
 func New(ctx context.Context, discovery *kubediscovery.Client, promRegistry *prometheus.Registry,
-	allowUnschedulable bool, cacheTTL time.Duration) (*Checker, error) {
+	allowUnschedulable bool, cacheTTL time.Duration, durationHistogramBuckets []float64) (*Checker, error) {
 	errorCounter := prometheus.NewCounterVec(
 		prometheus.CounterOpts{
 			Namespace: metricsNamespace,
@@ -38,7 +38,7 @@ func New(ctx context.Context, discovery *kubediscovery.Client, promRegistry *pro
 			Namespace: metricsNamespace,
 			Name:      "request_duration",
 			Help:      "Kubenurse request duration partitioned by target path",
-			Buckets:   prometheus.DefBuckets,
+			Buckets:   durationHistogramBuckets,
 		},
 		[]string{"type"},
 	)
diff --git a/internal/servicecheck/servicecheck_test.go b/internal/servicecheck/servicecheck_test.go
index b6604e68..07cf4db8 100644
--- a/internal/servicecheck/servicecheck_test.go
+++ b/internal/servicecheck/servicecheck_test.go
@@ -40,7 +40,7 @@ func TestCombined(t *testing.T) {
 	discovery, err := kubediscovery.New(context.Background(), fakeClient, false)
 	r.NoError(err)
 
-	checker, err := New(context.Background(), discovery, prometheus.NewRegistry(), false, 3*time.Second)
+	checker, err := New(context.Background(), discovery, prometheus.NewRegistry(), false, 3*time.Second, prometheus.DefBuckets)
 	r.NoError(err)
 	r.NotNil(checker)