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// Copyright 2017 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.
// +build !noarp
package collector
import (
"bufio"
"fmt"
"io"
"os"
"strings"
"github.com/go-kit/kit/log"
"github.com/prometheus/client_golang/prometheus"
)
type arpCollector struct {
entries *prometheus.Desc
logger log.Logger
}
func init() {
registerCollector("arp", defaultEnabled, NewARPCollector)
}
// NewARPCollector returns a new Collector exposing ARP stats.
func NewARPCollector(logger log.Logger) (Collector, error) {
return &arpCollector{
entries: prometheus.NewDesc(
prometheus.BuildFQName(namespace, "arp", "entries"),
"ARP entries by device",
[]string{"device"}, nil,
),
logger: logger,
}, nil
}
func getARPEntries() (map[string]uint32, error) {
file, err := os.Open(procFilePath("net/arp"))
if err != nil {
return nil, err
}
defer file.Close()
entries, err := parseARPEntries(file)
if err != nil {
return nil, err
}
return entries, nil
}
// TODO: This should get extracted to the github.com/prometheus/procfs package
// to support more complete parsing of /proc/net/arp. Instead of adding
// more fields to this function's return values it should get moved and
// changed to support each field.
func parseARPEntries(data io.Reader) (map[string]uint32, error) {
scanner := bufio.NewScanner(data)
entries := make(map[string]uint32)
for scanner.Scan() {
columns := strings.Fields(scanner.Text())
if len(columns) < 6 {
return nil, fmt.Errorf("unexpected ARP table format")
}
if columns[0] != "IP" {
deviceIndex := len(columns) - 1
entries[columns[deviceIndex]]++
}
}
if err := scanner.Err(); err != nil {
return nil, fmt.Errorf("failed to parse ARP info: %w", err)
}
return entries, nil
}
func (c *arpCollector) Update(ch chan<- prometheus.Metric) error {
entries, err := getARPEntries()
if err != nil {
return fmt.Errorf("could not get ARP entries: %w", err)
}
for device, entryCount := range entries {
ch <- prometheus.MustNewConstMetric(
c.entries, prometheus.GaugeValue, float64(entryCount), device)
}
return nil
}
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