本篇内容有点长，代码有点多。有兴趣的可以坚持看下去，并动手实践，没兴趣的可以划走。本文分两大块，一是搞清楚prometheus四种类型的指标Counter，Gauge，Histogram，Summary用golang语言如何构造这4种类型对应的指标，二是搞清楚修改指标值的场景和方式。
| 指标类型 | 类别 | 描述 | 可应用场景 |
|---|---|---|---|
| Counter | 计数类 | 使用在累计指标单调递增或递减情况下，只能在目标重启后自动归零 | 服务请求处理数量、已完成任务数量、错误数量 |
| Guage | 测量类 | 使用可增可减的的数据情况下 | 当前内存/CPU使用情况、并发请求数量 |
| Histogram | 直方图类 | 使用统计指标信息在不同区间内的统计数量 | 延迟时间、响应大小。例如：0-1秒内的延迟时间、、0-5秒内的延迟时间、例如0-1kb之内的响应大小、0-5kb之内的响应大小 |
| Summary | 摘要类 | 类似于直方图，在客户端对百分位进行统计 | 延迟时间、响应大小。例如：超过百分之多少的人要满足需求的话，需要多长时间完成。 |
1. Gauge指标类型
1.1 不带label的基本例子
package main
import (
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
func main() {
// 定义指标
cpuUsage := prometheus.NewGauge(prometheus.GaugeOpts{
Name: "cpu_usage", // 指标名称
Help: "this is test metrics cpu usage", // 帮助信息
})
// 给指标设置值
cpuUsage.Set(89.56)
// 注册指标
prometheus.MustRegister(cpuUsage)
// 暴露指标
http.Handle("/metrics", promhttp.Handler())
http.ListenAndServe(":9900", nil)
}1.2 带有固定label指标的例子
package main
import (
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
func main() {
// 定义指标
cpuUsage := prometheus.NewGauge(prometheus.GaugeOpts{
Name: "cpu_usage", // 指标名称
Help: "this is test metrics cpu usage", // 帮助信息
ConstLabels: prometheus.Labels{"MachineType": "host"}, // label
})
// 给指标设置值
cpuUsage.Set(89.56)
// 注册指标
prometheus.MustRegister(cpuUsage)
// 暴露指标
http.Handle("/metrics", promhttp.Handler())
http.ListenAndServe(":9900", nil)
}1.3 带有非固定label指标的例子
package main
import (
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
func main() {
//定义带有不固定label的指标
mtu := prometheus.NewGaugeVec(prometheus.GaugeOpts{
Name: "interface_mtu",
Help: "网卡接口MTU",
}, []string{"interface", "Machinetype"})
// 给指标设置值
mtu.WithLabelValues("lo", "host").Set(1500)
mtu.WithLabelValues("ens32", "host").Set(1500)
mtu.WithLabelValues("eth0", "host").Set(1500)
// 注册指标
prometheus.MustRegister(mtu)
// 暴露指标
http.Handle("/metrics", promhttp.Handler())
http.ListenAndServe(":9900", nil)
}2. Counter指标类型
2.1 不带label的基本例子
package main
import (
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
func main() {
// 定义指标
reqTotal := prometheus.NewCounter(prometheus.CounterOpts{
Name: "current_request_total",
Help: "当前请求总数",
})
// 注册指标
prometheus.MustRegister(reqTotal)
// 设置值
reqTotal.Add(10)
// 暴露指标
http.Handle("/metrics", promhttp.Handler())
http.ListenAndServe(":9900", nil)
}2.2 带有固定label指标的例子
package main
import (
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
func main() {
// 定义指标
suceReqTotal := prometheus.NewCounter(prometheus.CounterOpts{
Name: "sucess_request_total",
Help: "请求成功的总数",
ConstLabels: prometheus.Labels{"StatusCode": "200"},
})
// 注册指标
prometheus.MustRegister(suceReqTotal)
// 设置值
suceReqTotal.Add(5675)
// 暴露指标
http.Handle("/metrics", promhttp.Handler())
http.ListenAndServe(":9900", nil)
}2.3 带有非固定label指标的例子
package main
import (
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
func main() {
// 定义指标
pathReqTotal := prometheus.NewCounterVec(prometheus.CounterOpts{
Name: "path_request_total",
Help: "path请求总数",
}, []string{"path"})
// 注册指标
prometheus.MustRegister(pathReqTotal)
// 设置值
pathReqTotal.WithLabelValues("/token").Add(37)
pathReqTotal.WithLabelValues("/auth").Add(23)
pathReqTotal.WithLabelValues("/user").Add(90)
pathReqTotal.WithLabelValues("/api").Add(67)
// 暴露指标
http.Handle("/metrics", promhttp.Handler())
http.ListenAndServe(":9900", nil)
}3. Histogram指标类型
3.1 不带label的基本例子
package main
import (
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
func main() {
// 定义指标
reqDelay := prometheus.NewHistogram(prometheus.HistogramOpts{
Name: "request_delay",
Help: "请求延迟，单位秒",
Buckets: prometheus.LinearBuckets(0, 3, 6), // 调用LinearBuckets生成区间，从0开始，宽度3，共6个Bucket
})
// 注册指标
prometheus.MustRegister(reqDelay)
// 设置值
reqDelay.Observe(6)
// 暴露指标
http.Handle("/metrics", promhttp.Handler())
http.ListenAndServe(":9900", nil)
}3.2 带固定label的例子
package main
import (
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
func main() {
// 定义指标
reqDelay := prometheus.NewHistogram(prometheus.HistogramOpts{
Name: "request_delay",
Help: "请求延迟，单位秒",
Buckets: prometheus.LinearBuckets(0, 3, 6), // 调用LinearBuckets生成区间，从0开始，宽度3，共6个Bucket
ConstLabels: prometheus.Labels{"path": "/api"},
})
// 注册指标
prometheus.MustRegister(reqDelay)
// 设置值
reqDelay.Observe(6)
// 暴露指标
http.Handle("/metrics", promhttp.Handler())
http.ListenAndServe(":9900", nil)
}3.3 带有非固定label的例子
package main
import (
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
func main() {
// 定义指标
reqDelay := prometheus.NewHistogramVec(prometheus.HistogramOpts{
Name: "request_delay",
Help: "请求延迟，单位秒",
Buckets: prometheus.LinearBuckets(0, 3, 6), // 调用LinearBuckets生成区间，从0开始，宽度3，共6个Bucket
}, []string{"path"})
// 注册指标
prometheus.MustRegister(reqDelay)
// 设置值
reqDelay.WithLabelValues("/api").Observe(6)
reqDelay.WithLabelValues("/user").Observe(3)
reqDelay.WithLabelValues("/delete").Observe(2)
reqDelay.WithLabelValues("/get_token").Observe(13)
// 暴露指标
http.Handle("/metrics", promhttp.Handler())
http.ListenAndServe(":9900", nil)
}4. Summary指标类型
4.1 不带label的例子
package main
import (
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
func main() {
// 定义指标
reqDelay := prometheus.NewSummary(prometheus.SummaryOpts{
Name: "request_delay",
Help: "请求延迟",
Objectives: map[float64]float64{0.5: 0.05, 0.90: 0.01, 0.99: 0.001}, // 百分比:精度
})
// 注册指标
prometheus.MustRegister(reqDelay)
// 设置值
reqDelay.Observe(4)
// 暴露指标
http.Handle("/metrics", promhttp.Handler())
http.ListenAndServe(":9900", nil)
}4.2 带有固定label的例子
package main
import (
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
func main() {
// 定义指标
reqDelay := prometheus.NewSummary(prometheus.SummaryOpts{
Name: "request_delay",
Help: "请求延迟",
Objectives: map[float64]float64{0.5: 0.05, 0.90: 0.01, 0.99: 0.001}, // 百分比:精度
ConstLabels: prometheus.Labels{"path": "/api"},
})
// 注册指标
prometheus.MustRegister(reqDelay)
// 设置值
reqDelay.Observe(4)
// 暴露指标
http.Handle("/metrics", promhttp.Handler())
http.ListenAndServe(":9900", nil)
}4.3 带有非固定label的例子
package main
import (
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
func main() {
// 定义指标
reqDelay := prometheus.NewSummaryVec(prometheus.SummaryOpts{
Name: "request_delay",
Help: "请求延迟",
Objectives: map[float64]float64{0.5: 0.05, 0.90: 0.01, 0.99: 0.001}, // 百分比:精度
}, []string{"path"})
// 注册指标
prometheus.MustRegister(reqDelay)
// 设置值
reqDelay.WithLabelValues("/api").Observe(4)
reqDelay.WithLabelValues("/token").Observe(2)
reqDelay.WithLabelValues("/user").Observe(3)
// 暴露指标
http.Handle("/metrics", promhttp.Handler())
http.ListenAndServe(":9900", nil)
}5. 值的修改
5.1 基于事件的触发来修改值，比如每访问1次/api就增1
基于事件的触发对指标的值进行修改，通常大多数是来自业务方面的指标需求，如自研的应用需要暴露相关指标给promethus进行监控、展示，那么指标采集的代码（指标定义、设置值）就要嵌入到自研应用代码里了。
package main
import (
"fmt"
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
func main() {
urlRequestTotal := prometheus.NewCounterVec(prometheus.CounterOpts{
Name: "urlRequestTotal",
Help: "PATH请求累计 单位 次",
}, []string{"path"})
http.HandleFunc("/api", func(w http.ResponseWriter, r *http.Request) {
urlRequestTotal.WithLabelValues(r.URL.Path).Inc() // 使用Inc函数进行增1
fmt.Fprintf(w, "Welcome to the api")
})
prometheus.MustRegister(urlRequestTotal)
http.Handle("/metrics", promhttp.Handler())
http.ListenAndServe(":9900", nil)
}5.2 基于时间周期的触发来修改值，比如下面的示例中，是每间隔1秒获取cpu负载指标
基于时间周期的触发，可以是多少秒、分、时、日、月、周。
package main
import (
"net/http"
"time"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
"github.com/shirou/gopsutil/load"
)
func main() {
cpuUsage := prometheus.NewGaugeVec(prometheus.GaugeOpts{
Name: "CpuLoad",
Help: "CPU负载",
}, []string{"time"})
// 开启一个子协程执行该匿名函数内的逻辑来给指标设置值，且每秒获取一次
go func() {
for range time.Tick(time.Second) {
info, _ := load.Avg()
cpuUsage.WithLabelValues("Load1").Set(float64(info.Load1))
cpuUsage.WithLabelValues("Load5").Set(float64(info.Load5))
cpuUsage.WithLabelValues("Load15").Set(float64(info.Load15))
}
}()
prometheus.MustRegister(cpuUsage)
http.Handle("/metrics", promhttp.Handler())
http.ListenAndServe(":9900", nil)
}5.3 基于每访问一次获取指标的URI才修改值，比如每次访问/metrics才去修改某些指标的值
下面的这个示例是，每访问一次/metrics就获取一次内存总容量
package main
import (
"fmt"
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
"github.com/shirou/gopsutil/mem"
)
func main() {
MemTotal := prometheus.NewGaugeFunc(prometheus.GaugeOpts{
Name: "MemTotal",
Help: "内存总容量 单位 GB",
}, func() float64 {
fmt.Println("call MemTotal ...")
info, _ := mem.VirtualMemory()
return float64(info.Total / 1024 / 1024 / 1024)
})
prometheus.MustRegister(MemTotal)
http.Handle("/metrics", promhttp.Handler())
http.ListenAndServe(":9900", nil)
}目前只有Gauge和Counter的指标类型有对应的函数，分别是NewGaugeFunc和NewCounterFunc，而且是固定的label。
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