Add UDP drops collector

Signed-off-by: Nicolas Laduguie <nicolas.laduguie@dolby.com>

README.md

@@ -158,6 +158,7 @@ thermal | Exposes thermal statistics like `pmset -g therm`. | Darwin
 thermal\_zone | Exposes thermal zone & cooling device statistics from `/sys/class/thermal`. | Linux
 time | Exposes the current system time. | _any_
 timex | Exposes selected adjtimex(2) system call stats. | Linux
+udp_drops | Exposes UDP total datagrams dropped from `/proc/net/udp` and `/proc/net/udp6`. | Linux
 udp_queues | Exposes UDP total lengths of the rx_queue and tx_queue from `/proc/net/udp` and `/proc/net/udp6`. | Linux
 uname | Exposes system information as provided by the uname system call. | Darwin, FreeBSD, Linux, OpenBSD
 vmstat | Exposes statistics from `/proc/vmstat`. | Linux

collector/fixtures/e2e-64k-page-output.txt

@@ -2991,6 +2991,7 @@ node_scrape_collector_success{collector="tapestats"} 1
 node_scrape_collector_success{collector="textfile"} 1
 node_scrape_collector_success{collector="thermal_zone"} 1
 node_scrape_collector_success{collector="time"} 1
+node_scrape_collector_success{collector="udp_drops"} 1
 node_scrape_collector_success{collector="udp_queues"} 1
 node_scrape_collector_success{collector="vmstat"} 1
 node_scrape_collector_success{collector="watchdog"} 1
@@ -3242,6 +3243,9 @@ node_time_clocksource_current_info{clocksource="tsc",device="0"} 1
 # TYPE node_time_seconds gauge
 # HELP node_time_zone_offset_seconds System time zone offset in seconds.
 # TYPE node_time_zone_offset_seconds gauge
+# HELP node_udp_drops_total Total number of datagrams dropped.
+# TYPE node_udp_drops_total counter
+node_udp_drops_total{ip="v4"} 100
 # HELP node_udp_queues Number of allocated memory in the kernel for UDP datagrams in bytes.
 # TYPE node_udp_queues gauge
 node_udp_queues{ip="v4",queue="rx"} 0

collector/fixtures/e2e-output.txt

@@ -3013,6 +3013,7 @@ node_scrape_collector_success{collector="tapestats"} 1
 node_scrape_collector_success{collector="textfile"} 1
 node_scrape_collector_success{collector="thermal_zone"} 1
 node_scrape_collector_success{collector="time"} 1
+node_scrape_collector_success{collector="udp_drops"} 1
 node_scrape_collector_success{collector="udp_queues"} 1
 node_scrape_collector_success{collector="vmstat"} 1
 node_scrape_collector_success{collector="watchdog"} 1
@@ -3264,6 +3265,9 @@ node_time_clocksource_current_info{clocksource="tsc",device="0"} 1
 # TYPE node_time_seconds gauge
 # HELP node_time_zone_offset_seconds System time zone offset in seconds.
 # TYPE node_time_zone_offset_seconds gauge
+# HELP node_udp_drops_total Total number of datagrams dropped.
+# TYPE node_udp_drops_total counter
+node_udp_drops_total{ip="v4"} 100
 # HELP node_udp_queues Number of allocated memory in the kernel for UDP datagrams in bytes.
 # TYPE node_udp_queues gauge
 node_udp_queues{ip="v4",queue="rx"} 0

collector/udp_drops_linux.go

@@ -0,0 +1,90 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !noudp_drops
+// +build !noudp_drops
+
+package collector
+
+import (
+	"errors"
+	"fmt"
+	"log/slog"
+	"os"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/procfs"
+)
+
+type (
+	udpDropsCollector struct {
+		fs     procfs.FS
+		desc   *prometheus.Desc
+		logger *slog.Logger
+	}
+)
+
+func init() {
+	registerCollector("udp_drops", defaultEnabled, NewUDPdropsCollector)
+}
+
+// NewUDPdropsCollector returns a new Collector exposing network udp drops count.
+func NewUDPdropsCollector(logger *slog.Logger) (Collector, error) {
+	fs, err := procfs.NewFS(*procPath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open procfs: %w", err)
+	}
+	return &udpDropsCollector{
+		fs: fs,
+		desc: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, "udp", "drops_total"),
+			"Total number of datagrams dropped.",
+			[]string{"ip"}, nil,
+		),
+		logger: logger,
+	}, nil
+}
+
+func (c *udpDropsCollector) Update(ch chan<- prometheus.Metric) error {
+
+	s4, errIPv4 := c.fs.NetUDPSummary()
+	if errIPv4 == nil {
+		if s4.Drops != nil {
+			ch <- prometheus.MustNewConstMetric(c.desc, prometheus.CounterValue, float64(*s4.Drops), "v4")
+		}
+	} else {
+		if errors.Is(errIPv4, os.ErrNotExist) {
+			c.logger.Debug("not collecting ipv4 based metrics")
+		} else {
+			return fmt.Errorf("couldn't get udp drops: %w", errIPv4)
+		}
+	}
+
+	s6, errIPv6 := c.fs.NetUDP6Summary()
+	if errIPv6 == nil {
+		if s6.Drops != nil {
+			ch <- prometheus.MustNewConstMetric(c.desc, prometheus.CounterValue, float64(*s6.Drops), "v6")
+		}
+	} else {
+		if errors.Is(errIPv6, os.ErrNotExist) {
+			c.logger.Debug("not collecting ipv6 based metrics")
+		} else {
+			return fmt.Errorf("couldn't get udp6 drops: %w", errIPv6)
+		}
+	}
+
+	if errors.Is(errIPv4, os.ErrNotExist) && errors.Is(errIPv6, os.ErrNotExist) {
+		return ErrNoData
+	}
+	return nil
+}

end-to-end-test.sh

@@ -48,6 +48,7 @@ enabled_collectors=$(cat << COLLECTORS
   textfile
   thermal_zone
   udp_queues
+  udp_drops
   vmstat
   watchdog
   wifi