nagios_varnish_plugin - Monitoring for Varnish Cache

nagios_varnish_plugin.go

// nagios_varnish_plugin - Monitoring for Varnish Cache
// Copyright (C) 2015 Matous Jan Fialka, <http://mjf.cz/>
// Released under the terms of "The MIT License"

package main

import (
	"encoding/json"
	"fmt"
	"log"
	"os/exec"
	"strconv"
	"strings"
)

const prefix = "Varnish_Cache."

func main() {
	out, err := exec.Command("varnishstat", "-j").Output()
	if err != nil {
		log.Fatalf("%v", err)
	}

	var jdata interface{}
	err = json.Unmarshal(out, &jdata)
	if err != nil {
		log.Fatalf("%v", err)
	}

	metric := make(map[string]float64)
	info := make(map[string]string)
	data := jdata.(map[string]interface{})
	for key, value := range data {
		switch item := value.(type) {
		case map[string]interface{}:
			for skey, svalue := range item {
				switch sitem := svalue.(type) {
				case float64:
					if strings.Contains(skey, "value") {
						metric[prefix+key] = sitem
					}
				case string:
					if strings.Contains(skey, "description") {
						info[prefix+key] = sitem
					}
				}
			}
		}
	}

	metric[prefix+"Custom.cache_hit_ratio"] = func() float64 {
		hit := metric[prefix+"MAIN.cache_hit"]
		total := hit + metric[prefix+"MAIN.cache_miss"]
		if total != 0 {
			return (hit / total) * 100
		}
		return 0
	}()

	metric[prefix+"Custom.sess_accept_ratio"] = func() float64 {
		req := metric[prefix+"MAIN.s_req"]
		if req != 0 {
			return (metric[prefix+"MAIN.sess_conn"] / req) * 100
		}
		return 0
	}()

	metric[prefix+"Custom.backend_success_ratio"] = func() float64 {
		conn := metric[prefix+"MAIN.backend_conn"]
		total := conn + metric[prefix+"MAIN.backend_fail"]
		if total != 0 {
			return (conn / total) * 100
		}
		return 0
	}()

	for key, value := range metric {
		svalue := strconv.FormatFloat(value, 'f', 5, 64)
		ilen := len(info[key])
		var sinfo string = "Undescribed"
		if ilen > 0 {
			sinfo = strings.ToUpper(string(info[key][0]))
			if ilen > 1 {
				sinfo += info[key][1:]
			}
		}
		fmt.Println("0", key, "value="+svalue, "OK -", sinfo)
	}
}

// vi:ft=go

Warning

This is just toy code!

TODO

• Provide support for varnishadm param.show -l
• Provide support for "counting" values
• Provide support for "counting" values storage configuration
• Provide support for metrics configuration
• Provide support for stats items configuration
• Provide support for configurable thresholds for both stats items and metrics
• Modularize and document source code

Also create:

• collectd_varnish_plugin (plugin for collectd)
• snmpd_varnish_plugin (support for snmpd)

Compile

$ go build nagios_varnish_plugin.go

Install

$ sftp root@<hostname>:/usr/share/check-mk-agent/local/
sftp> put nagios_varnish_plugin
sftp> quit

Check_MK

Rescan services in the WATO plugin for the given <hostname>.