Prometheus Custom Registry not working

Question

I'm still learning Prometheus so maybe I'm not sure about the problem correctly.

All I need is a custom registry where I can only collect my metrics. Since I'm learning Prometheus I really not interested in default metric provide by Prometheus namely all the go metrics like go_gc_duration_seconds, go_gc_duration_seconds_count, go_threads, promhttp_metric_handler_requests_in_flight etc

package main

import (
    "fmt"
    "log"
    "math/rand"
    "net/http"
    "sync"
    "time"

    "github.com/prometheus/client_golang/prometheus"
    "github.com/prometheus/client_golang/prometheus/promhttp"
)

var Types = [2]string{"Random", "Simple"}

type Queue struct {
    mutex sync.Mutex
    jobs  []Job
}

func (q *Queue) Add(job Job) {
    q.mutex.Lock()
    q.jobs = append(q.jobs, job)
    q.mutex.Unlock()
}

func (q *Queue) Dequeue() Job {
    q.mutex.Lock()
    job := q.jobs[0]
    q.jobs = q.jobs[1:]
    q.mutex.Unlock()
    return job
}

type Job struct {
    message string
    Type    string
}

func (j *Job) Run() {
    fmt.Println(j.message)
}

var jobsInQueue = prometheus.NewGaugeVec(
    prometheus.GaugeOpts{
        Name: "jobs_in_queue",
        Help: "Current number of jobs in the queue",
    },
    []string{"job_type"},
)
var register = prometheus.NewRegistry()
var queue = &Queue{}

func init() {
    rand.Seed(2)
    // prometheus.MustRegister(jobsInQueue)
    // register the collector.. 
    register.MustRegister(jobsInQueue)
    queue.jobs = make([]Job, 0)
}

func main() {

    go func() {
        i := 0
        for {
            job := Job{}
            num := rand.Intn(2)
            type_d := Types[num]
            job.Type = type_d
            job.message = fmt.Sprintf("[%s] job %d", type_d, i)
            enqueueJob(job)
            fmt.Println(i)
            i++
            time.Sleep(1 * time.Second)
        }
    }()

    // sleep so that we do not read from a empty queue
    time.Sleep(2 * time.Millisecond)

    go func() {
        for {
            runNextJob()
            time.Sleep(2 * time.Second)
        }
    }()

    http.Handle("/metrics", promhttp.Handler())
    log.Fatal(http.ListenAndServe(":8080", nil))

}

func enqueueJob(job Job) {
    queue.Add(job)
    jobsInQueue.WithLabelValues(job.Type).Inc()
}

func runNextJob() {
    job := queue.Dequeue()
    jobsInQueue.WithLabelValues(job.Type).Dec()
    job.Run()
}

But when I run the following code I don't see my i.e jobs_in_queue metric in /metrics endpoint of 8080.

How am I suppose to get this work.

Nicholas Nicholas · Accepted Answer · 2018-08-16T16:26:06

promhttp.Handler() creates a handler for the default registry. You need to use promhttp.HandlerFor(registry, HandlerOpts{})

Prometheus Custom Registry not working

1 Answers