Add flag to set custom buckets for prometheus histogram

cmd/nginx/flags.go

@@ -22,13 +22,15 @@ import (
 	"os"
 	"time"
 
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/spf13/pflag"
 	apiv1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/labels"
 	"k8s.io/ingress-nginx/internal/ingress/annotations/parser"
 	"k8s.io/ingress-nginx/internal/ingress/controller"
 	ngx_config "k8s.io/ingress-nginx/internal/ingress/controller/config"
 	"k8s.io/ingress-nginx/internal/ingress/controller/ingressclass"
+	"k8s.io/ingress-nginx/internal/ingress/metric/collectors"
 	"k8s.io/ingress-nginx/internal/ingress/status"
 	ing_net "k8s.io/ingress-nginx/internal/net"
 	"k8s.io/ingress-nginx/internal/nginx"
@@ -161,6 +163,9 @@ Requires the update-status parameter.`)
 			`Enables the collection of NGINX metrics`)
 		metricsPerHost = flags.Bool("metrics-per-host", true,
 			`Export metrics per-host`)
+		timeBuckets         = flags.Float64Slice("time-buckets", prometheus.DefBuckets, "Set of buckets which will be used for prometheus histogram metrics such as RequestTime, ResponseTime")
+		lengthBuckets       = flags.Float64Slice("length-buckets", prometheus.LinearBuckets(10, 10, 10), "Set of buckets which will be used for prometheus histogram metrics such as RequestLength, ResponseLength")
+		sizeBuckets         = flags.Float64Slice("size-buckets", prometheus.ExponentialBuckets(10, 10, 7), "Set of buckets which will be used for prometheus histogram metrics such as BytesSent")
 		monitorMaxBatchSize = flags.Int("monitor-max-batch-size", 10000, "Max batch size of NGINX metrics")
 
 		httpPort  = flags.Int("http-port", 80, `Port to use for servicing HTTP traffic.`)
@@ -283,6 +288,12 @@ https://blog.maxmind.com/2019/12/18/significant-changes-to-accessing-and-using-g
 		}
 	}
 
+	var histogramBuckets = &collectors.HistogramBuckets{
+		TimeBuckets:   *timeBuckets,
+		LengthBuckets: *lengthBuckets,
+		SizeBuckets:   *sizeBuckets,
+	}
+
 	ngx_config.EnableSSLChainCompletion = *enableSSLChainCompletion
 
 	config := &controller.Configuration{
@@ -293,6 +304,7 @@ https://blog.maxmind.com/2019/12/18/significant-changes-to-accessing-and-using-g
 		EnableProfiling:            *profiling,
 		EnableMetrics:              *enableMetrics,
 		MetricsPerHost:             *metricsPerHost,
+		MetricsBuckets:             histogramBuckets,
 		MonitorMaxBatchSize:        *monitorMaxBatchSize,
 		DisableServiceExternalName: *disableServiceExternalName,
 		EnableSSLPassthrough:       *enableSSLPassthrough,

cmd/nginx/main.go

@@ -133,7 +133,7 @@ func main() {
 
 	mc := metric.NewDummyCollector()
 	if conf.EnableMetrics {
-		mc, err = metric.NewCollector(conf.MetricsPerHost, reg, conf.IngressClassConfiguration.Controller)
+		mc, err = metric.NewCollector(conf.MetricsPerHost, reg, conf.IngressClassConfiguration.Controller, *conf.MetricsBuckets)
 		if err != nil {
 			klog.Fatalf("Error creating prometheus collector:  %v", err)
 		}

internal/ingress/controller/controller.go

@@ -41,6 +41,7 @@ import (
 	"k8s.io/ingress-nginx/internal/ingress/controller/ingressclass"
 	"k8s.io/ingress-nginx/internal/ingress/controller/store"
 	"k8s.io/ingress-nginx/internal/ingress/errors"
+	"k8s.io/ingress-nginx/internal/ingress/metric/collectors"
 	"k8s.io/ingress-nginx/internal/k8s"
 	"k8s.io/ingress-nginx/internal/nginx"
 	"k8s.io/klog/v2"
@@ -97,6 +98,7 @@ type Configuration struct {
 
 	EnableMetrics  bool
 	MetricsPerHost bool
+	MetricsBuckets *collectors.HistogramBuckets
 
 	FakeCertificate *ingress.SSLCert
 

internal/ingress/metric/collectors/socket.go

@@ -56,6 +56,13 @@ type socketData struct {
 	Path      string `json:"path"`
 }
 
+// HistogramBuckets allow customizing prometheus histogram buckets values
+type HistogramBuckets struct {
+	TimeBuckets   []float64
+	LengthBuckets []float64
+	SizeBuckets   []float64
+}
+
 // SocketCollector stores prometheus metrics and ingress meta-data
 type SocketCollector struct {
 	prometheus.Collector
@@ -79,6 +86,8 @@ type SocketCollector struct {
 	hosts sets.String
 
 	metricsPerHost bool
+
+	buckets HistogramBuckets
 }
 
 var (
@@ -101,7 +110,7 @@ var defObjectives = map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001}
 
 // NewSocketCollector creates a new SocketCollector instance using
 // the ingress watch namespace and class used by the controller
-func NewSocketCollector(pod, namespace, class string, metricsPerHost bool) (*SocketCollector, error) {
+func NewSocketCollector(pod, namespace, class string, metricsPerHost bool, buckets HistogramBuckets) (*SocketCollector, error) {
 	socket := "/tmp/prometheus-nginx.socket"
 	// unix sockets must be unlink()ed before being used
 	_ = syscall.Unlink(socket)
@@ -138,6 +147,7 @@ func NewSocketCollector(pod, namespace, class string, metricsPerHost bool) (*Soc
 				Help:        "The time spent on receiving the response from the upstream server",
 				Namespace:   PrometheusNamespace,
 				ConstLabels: constLabels,
+				Buckets:     buckets.TimeBuckets,
 			},
 			requestTags,
 		),
@@ -147,6 +157,7 @@ func NewSocketCollector(pod, namespace, class string, metricsPerHost bool) (*Soc
 				Help:        "The response length (including request line, header, and request body)",
 				Namespace:   PrometheusNamespace,
 				ConstLabels: constLabels,
+				Buckets:     buckets.LengthBuckets,
 			},
 			requestTags,
 		),
@@ -157,6 +168,7 @@ func NewSocketCollector(pod, namespace, class string, metricsPerHost bool) (*Soc
 				Help:        "The request processing time in milliseconds",
 				Namespace:   PrometheusNamespace,
 				ConstLabels: constLabels,
+				Buckets:     buckets.TimeBuckets,
 			},
 			requestTags,
 		),
@@ -165,7 +177,7 @@ func NewSocketCollector(pod, namespace, class string, metricsPerHost bool) (*Soc
 				Name:        "request_size",
 				Help:        "The request length (including request line, header, and request body)",
 				Namespace:   PrometheusNamespace,
-				Buckets:     prometheus.LinearBuckets(10, 10, 10), // 10 buckets, each 10 bytes wide.
+				Buckets:     buckets.LengthBuckets,
 				ConstLabels: constLabels,
 			},
 			requestTags,
@@ -186,7 +198,7 @@ func NewSocketCollector(pod, namespace, class string, metricsPerHost bool) (*Soc
 				Name:        "bytes_sent",
 				Help:        "The number of bytes sent to a client",
 				Namespace:   PrometheusNamespace,
-				Buckets:     prometheus.ExponentialBuckets(10, 10, 7), // 7 buckets, exponential factor of 10.
+				Buckets:     buckets.SizeBuckets,
 				ConstLabels: constLabels,
 			},
 			requestTags,

internal/ingress/metric/collectors/socket_test.go

@@ -68,6 +68,17 @@ func TestNewUDPLogListener(t *testing.T) {
 }
 
 func TestCollector(t *testing.T) {
+
+	buckets := struct {
+		TimeBuckets   []float64
+		LengthBuckets []float64
+		SizeBuckets   []float64
+	}{
+		prometheus.DefBuckets,
+		prometheus.LinearBuckets(10, 10, 10),
+		prometheus.ExponentialBuckets(10, 10, 7),
+	}
+
 	cases := []struct {
 		name            string
 		data            []string
@@ -338,7 +349,7 @@ func TestCollector(t *testing.T) {
 		t.Run(c.name, func(t *testing.T) {
 			registry := prometheus.NewPedanticRegistry()
 
-			sc, err := NewSocketCollector("pod", "default", "ingress", true)
+			sc, err := NewSocketCollector("pod", "default", "ingress", true, buckets)
 			if err != nil {
 				t.Errorf("%v: unexpected error creating new SocketCollector: %v", c.name, err)
 			}

internal/ingress/metric/main.go

@@ -68,7 +68,7 @@ type collector struct {
 }
 
 // NewCollector creates a new metric collector the for ingress controller
-func NewCollector(metricsPerHost bool, registry *prometheus.Registry, ingressclass string) (Collector, error) {
+func NewCollector(metricsPerHost bool, registry *prometheus.Registry, ingressclass string, buckets collectors.HistogramBuckets) (Collector, error) {
 	podNamespace := os.Getenv("POD_NAMESPACE")
 	if podNamespace == "" {
 		podNamespace = "default"
@@ -86,7 +86,7 @@ func NewCollector(metricsPerHost bool, registry *prometheus.Registry, ingresscla
 		return nil, err
 	}
 
-	s, err := collectors.NewSocketCollector(podName, podNamespace, ingressclass, metricsPerHost)
+	s, err := collectors.NewSocketCollector(podName, podNamespace, ingressclass, metricsPerHost, buckets)
 	if err != nil {
 		return nil, err
 	}