How to Add Built‑In System Health Reports to Go Services with go‑commons

Small teams often consider node_exporter heavy and need a full Prometheus + Grafana stack just to view basic CPU and memory usage.

The go-commons library provides a lightweight, plug‑and‑play alternative that exposes system metrics from the same Go process as the application.

Installation

go get github.com/Rodert/go-commons

Minimal monitoring service (<50 lines)

package main

import (
    "fmt"
    "net/http"
    "sync/atomic"
    "time"

    "github.com/Rodert/go-commons/metrics"
)

var qpsCounter int64

func main() {
    // business endpoint
    http.HandleFunc("/hello", func(w http.ResponseWriter, r *http.Request) {
        atomic.AddInt64(&qpsCounter, 1)
        fmt.Fprintln(w, "Hello, go-commons!")
    })

    // metrics endpoint
    http.HandleFunc("/metrics", func(w http.ResponseWriter, r *http.Request) {
        mem := metrics.GetMemoryUsage() // returns float64 percentage
        cpu := metrics.GetCPUUsage()   // returns float64 percentage
        qps := atomic.SwapInt64(&qpsCounter, 0)
        fmt.Fprintf(w, "qps %d
", qps)
        fmt.Fprintf(w, "memory_usage %.2f
", mem)
        fmt.Fprintf(w, "cpu_usage %.2f
", cpu)
    })

    // reset QPS every second
    go func() {
        for range time.Tick(time.Second) {
            atomic.StoreInt64(&qpsCounter, 0)
        }
    }()

    fmt.Println("server started at :8080")
    http.ListenAndServe(":8080", nil)
}

Run with go run main.go; the server listens on port 8080.

Verification

Business request: curl http://localhost:8080/hello Metrics request: curl http://localhost:8080/metrics Typical output:

qps 3
memory_usage 42.78
cpu_usage 5.13

The service acts as a miniature node_exporter without requiring a separate binary.

Prometheus integration

Add a scrape job:

scrape_configs:
  - job_name: "go-app"
    static_configs:
      - targets: ["localhost:8080"]

Grafana can then display QPS, memory, and CPU on a single dashboard.

Key characteristics

Zero‑cost onboarding: a single go get and a few lines of code.

Lightweight: no separate node_exporter deployment.

Unified endpoint: business and system metrics share /metrics.

Open‑source repository at https://github.com/Rodert/go-commons; future releases may add network, disk, and goroutine metrics.