特点：数据可增减（反应当前状态）。

1. 不带lab的Gauge

1.1 定义指标

语法

• 实例化

func NewGauge(opts GaugeOpts) Gauge
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• GaugeOpts

type GaugeOpts Opts
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• 结构体Opts

type Opts struct {
    Namespace   string
    Subsystem   string
    Name        string
    Help        string
    ConstLabels Labels
}
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完整示例

• 写一段简单的exporter如下：

package main

import (
	"flag"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"log"
	"net/http"
)

//自定义端口
var addr = flag.String("listen-address", ":1840", "The address to listen on for HTTP requests")

var (
	numOfBuns = prometheus.NewGauge(prometheus.GaugeOpts{
		Namespace: "xi_shu",
		Subsystem: "jing_zhou_team",
		Name:      "guanyu_eaten_num",
		Help:      "Number of steamed buns eaten by Guan Yu",
	})
)

func init() {
	prometheus.MustRegister(numOfBuns)
}

func main() {
	flag.Parse()
	http.Handle("/metrics", promhttp.Handler())
	log.Fatal(http.ListenAndServe(*addr, nil))
}
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• 结果如下
  我们访问http://127.0.0.1:1840/metrics页面，可以找到如下一段

# HELP xi_shu_jing_zhou_team_guanyu_eaten_num Number of steamed buns eaten by Guan Yu
# TYPE xi_shu_jing_zhou_team_guanyu_eaten_num gauge
xi_shu_jing_zhou_team_guanyu_eaten_num 0
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如上可知，我们的指标是用Opts结构体的实例化拼接出来的。

1.2 给指标取值

语法

• add() 增加n

func (Gauge) Add(float64)
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• sub() 减去n

func (Gauge) Sub(float64)
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• Inc() 增加1

func (Gauge) Inc()
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• dec() 减少1

func (Gauge) Dec()
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• set() 重新设置

func (Gauge) Set(float64)
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• 设置值为当前时间时间戳

func (Gauge) SetToCurrentTime()
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完整示例

• 代码

package main

import (
	"flag"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"log"
	"net/http"
	"time"
)
var addr = flag.String("listen-address", ":1840", "The address to listen on for HTTP requests")

var (
	numOfBuns = prometheus.NewGauge(prometheus.GaugeOpts{
		Namespace: "xi_shu",
		Subsystem: "jing_zhou_team",
		Name:      "guanyu_eaten_num",
		Help:      "Number of steamed buns eaten by Guan Yu",
	})
)

func init() {
	prometheus.MustRegister(numOfBuns)
}

func main() {
	flag.Parse()
	go func() {
		for true {
			numOfBuns.Add(2)
			time.Sleep(time.Second)
		}
	}()
	http.Handle("/metrics", promhttp.Handler())
	log.Fatal(http.ListenAndServe(*addr, nil))
}
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• 结果

我们不断刷新可见，每秒钟关羽吃的馒头+2

# HELP xi_shu_jing_zhou_team_guanyu_eaten_num Number of steamed buns eaten by Guan Yu
# TYPE xi_shu_jing_zhou_team_guanyu_eaten_num gauge
xi_shu_jing_zhou_team_guanyu_eaten_num 24
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2. 带lab的Gauge

2.1 定义指标

语法

• 实例化

func NewGaugeVec(opts GaugeOpts, labelNames []string) *GaugeVec
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• GaugeOpts 见上例

完整示例

package main

import (
	"flag"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"log"
	"net/http"
	"time"
)

//自定义端口
var addr = flag.String("listen-address", ":1840", "The address to listen on for HTTP requests")

var (
	numOfBuns = prometheus.NewGaugeVec(prometheus.GaugeOpts{
		Namespace: "xi_shu",
		Subsystem: "jing_zhou_team",
		Name:      "eaten_num",
		Help:      "Number of steamed buns eaten by Guan Yu",
	},[]string{"name","age"})
)

func init() {
	prometheus.MustRegister(numOfBuns)
}

func main() {
	flag.Parse()
	http.Handle("/metrics", promhttp.Handler())
	log.Fatal(http.ListenAndServe(*addr, nil))
}
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• 结果显示
  有lab的Counter没有赋值是看不见的（而上例可知，没有tag的Counter模式值是0。）

2.2 取值

语法

• 添加lab
  实例化之后，需要先给实例打上lab，因为不同的lab会单独作为一个数据显示。

func (v *GaugeVec) WithLabelValues(lvs ...string) Gauge
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• 取值

见前文，同“不带lab的Gauge”

完整示例

• 代码如下

package main

import (
	"flag"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"log"
	"net/http"
	"time"
)

//自定义端口
var addr = flag.String("listen-address", ":1840", "The address to listen on for HTTP requests")

var (
	numOfBuns = prometheus.NewGaugeVec(prometheus.GaugeOpts{
		Namespace: "xi_shu",
		Subsystem: "jing_zhou_team",
		Name:      "eaten_num",
		Help:      "Number of steamed buns eaten by Guan Yu",
	},[]string{"name","age"})
)

func init() {
	prometheus.MustRegister(numOfBuns)
}

func main() {
	flag.Parse()
	go func() {
		for true {
			numOfBuns.WithLabelValues("guan_yu","25").Add(2)
			time.Sleep(time.Second)
		}
	}()
	go func() {
		for true {
			numOfBuns.WithLabelValues("zhang_fei","22").Add(3)
			time.Sleep(time.Second)
		}
	}()
	http.Handle("/metrics", promhttp.Handler())
	log.Fatal(http.ListenAndServe(*addr, nil))
}
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• 结果

# HELP xi_shu_jing_zhou_team_eaten_num Number of steamed buns eaten by Guan Yu
# TYPE xi_shu_jing_zhou_team_eaten_num gauge
xi_shu_jing_zhou_team_eaten_num{age="22",name="zhang_fei"} 21
xi_shu_jing_zhou_team_eaten_num{age="25",name="guan_yu"} 14
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