prometheus增加和删除labels

在Prometheus中，一个metric可以有多个label，label由key和value组成。

import (
    "github.com/prometheus/client_golang/prometheus"
    "github.com/prometheus/client_golang/prometheus/promauto"
)

var (
    httpRequestCount = promauto.NewCounterVec(
        prometheus.CounterOpts{
            Name: "http_request_count",
            Help: "The total number of http request",
        },
        []string{"url", "is_success"},
    )
)

// 增加label：基于标签来增加数量
httpRequestCount.WithLabelValues("http://127.0.0.1:80/test", "true").Inc()
// 删除label
httpRequestCount.DeleteLabelValues("http://127.0.0.1:80/test", "true")