telegraf/plugins/inputs/varnish/varnish.go

165 lines
3.6 KiB
Go
Raw Normal View History

// +build !windows
package varnish
import (
"bufio"
"bytes"
"fmt"
"os"
"os/exec"
"strconv"
"strings"
"github.com/influxdata/telegraf"
"github.com/influxdata/telegraf/internal"
"github.com/influxdata/telegraf/plugins/inputs"
"time"
)
const (
kwAll = "all"
)
// Varnish is used to store configuration values
type Varnish struct {
Stats []string
Binary string
}
var defaultStats = []string{"MAIN.cache_hit", "MAIN.cache_miss", "MAIN.uptime"}
var defaultBinary = "/usr/bin/varnishstat"
var varnishSampleConfig = `
## The default location of the varnishstat binary can be overridden with:
binary = "/usr/bin/varnishstat"
## By default, telegraf gather stats for 3 metric points.
## Setting stats will override the defaults shown below.
## stats may also be set to ["all"], which will collect all stats
stats = ["MAIN.cache_hit", "MAIN.cache_miss", "MAIN.uptime"]
`
func (s *Varnish) Description() string {
return "A plugin to collect stats from Varnish HTTP Cache"
}
// SampleConfig displays configuration instructions
func (s *Varnish) SampleConfig() string {
return fmt.Sprintf(varnishSampleConfig, strings.Join(defaultStats, "\",\""))
}
func (s *Varnish) setDefaults() {
if len(s.Stats) == 0 {
s.Stats = defaultStats
}
if s.Binary == "" {
s.Binary = defaultBinary
}
}
// Builds a filter function that will indicate whether a given stat should
// be reported
func (s *Varnish) statsFilter() func(string) bool {
s.setDefaults()
// Build a set for constant-time lookup of whether stats should be included
filter := make(map[string]struct{})
for _, s := range s.Stats {
filter[s] = struct{}{}
}
// Create a function that respects the kwAll by always returning true
// if it is set
return func(stat string) bool {
if s.Stats[0] == kwAll {
return true
}
_, found := filter[stat]
return found
}
}
// Shell out to varnish_stat and return the output
var varnishStat = func(cmdName string) (*bytes.Buffer, error) {
cmdArgs := []string{"-1"}
cmd := exec.Command(cmdName, cmdArgs...)
var out bytes.Buffer
cmd.Stdout = &out
err := internal.RunTimeout(cmd, time.Millisecond*200)
if err != nil {
return &out, fmt.Errorf("error running varnishstat: %s", err)
}
return &out, nil
}
// Gather collects the configured stats from varnish_stat and adds them to the
// Accumulator
//
// The prefix of each stat (eg MAIN, MEMPOOL, LCK, etc) will be used as a
// 'section' tag and all stats that share that prefix will be reported as fields
// with that tag
func (s *Varnish) Gather(acc telegraf.Accumulator) error {
s.setDefaults()
out, err := varnishStat(s.Binary)
if err != nil {
return fmt.Errorf("error gathering metrics: %s", err)
}
statsFilter := s.statsFilter()
sectionMap := make(map[string]map[string]interface{})
scanner := bufio.NewScanner(out)
for scanner.Scan() {
cols := strings.Fields(scanner.Text())
if len(cols) < 2 {
continue
}
if !strings.Contains(cols[0], ".") {
continue
}
stat := cols[0]
value := cols[1]
if !statsFilter(stat) {
continue
}
parts := strings.SplitN(stat, ".", 2)
section := parts[0]
field := parts[1]
// Init the section if necessary
if _, ok := sectionMap[section]; !ok {
sectionMap[section] = make(map[string]interface{})
}
sectionMap[section][field], err = strconv.Atoi(value)
if err != nil {
fmt.Fprintf(os.Stderr, "Expected a numeric value for %s = %v\n",
stat, value)
}
}
for section, fields := range sectionMap {
tags := map[string]string{
"section": section,
}
if len(fields) == 0 {
continue
}
acc.AddFields("varnish", fields, tags)
}
return nil
}
func init() {
inputs.Add("varnish", func() telegraf.Input { return &Varnish{} })
}