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|
package main
import (
"flag"
"fmt"
"io/fs"
"log/slog"
"maps"
"net/http"
"os"
"path/filepath"
"slices"
"strconv"
"time"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
var (
httpHost string
httpPort int
interval int
namespace string
path string
subsystem string
customLabels MapVar
extensionKeys map[string]bool
gauges map[string]*prometheus.GaugeVec
)
func main() {
// Set options
flag.StringVar(&httpHost, "host", "[::]", "The path to export metrics of")
flag.IntVar(&httpPort, "port", 9091, "The path to export metrics of")
flag.IntVar(&interval, "interval", 10, "The path to export metrics of")
flag.StringVar(&namespace, "namespace", "fsdir_exporter", "Namespace to use for the Prometheus metrics")
flag.StringVar(&path, "path", "", "The path to export metrics of")
flag.StringVar(&subsystem, "subsystem", "", "Subsystem to use for the Prometheus metrics")
flag.Var(&customLabels, "label", "Additional labels to apply to the metrics")
flag.Parse()
// Check required options
if path == "" {
slog.Error("No path set")
os.Exit(1)
}
// Create a slice of all label keys to include user-defined additions
labelKeys := slices.Collect(maps.Keys(customLabels))
labelKeys = append(labelKeys, "extension")
// Instantiate Prometheus metrics
gauges = make(map[string]*prometheus.GaugeVec)
gauges["count"] = prometheus.NewGaugeVec(
prometheus.GaugeOpts{
Namespace: namespace,
Subsystem: subsystem,
Name: "count",
Help: "Number of files found in the given directory",
},
labelKeys,
)
gauges["size"] = prometheus.NewGaugeVec(
prometheus.GaugeOpts{
Namespace: namespace,
Subsystem: subsystem,
Name: "size",
Help: "Size (in bytes) of files found in the given directory",
},
labelKeys,
)
// Register Prometheus metrics
slog.Debug("Registering Prometheus metrics")
prometheus.MustRegister(
gauges["count"],
gauges["size"],
)
// Start the update process
extensionKeys = make(map[string]bool)
update()
go updateLoop()
// Bind HTTP handlers
slog.Debug("Binding HTTP handlers")
http.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, "OK\n")
})
http.Handle("/metrics", promhttp.Handler())
// Run HTTP service
slog.Info("Serving HTTP requests", "address", httpHost, "port", httpPort)
err := http.ListenAndServe(httpHost+":"+strconv.Itoa(httpPort), nil)
slog.Error(err.Error())
}
func mergeLabels(extra map[string]string) prometheus.Labels {
labels := make(map[string]string)
maps.Copy(labels, customLabels)
maps.Copy(labels, extra)
return labels
}
func update() {
sizes := make(map[string]float64)
counts := make(map[string]float64)
slog.Debug("Scanning filesystem for updates")
err := filepath.Walk(path, func(path string, info fs.FileInfo, err error) error {
if err != nil {
return err
}
if info.IsDir() {
return nil
}
ext := filepath.Ext(info.Name())
// Remove the leading . if needed
if ext != "" {
ext = ext[1:]
}
extensionKeys[ext] = true
counts[ext]++
sizes[ext] += float64(info.Size())
return nil
})
if err != nil {
slog.Error(fmt.Sprintf("error walking the path %v\n", err))
return
}
// Loop over all keys and set the respective gauge values
slog.Debug("Writing new values to metrics")
for key, _ := range extensionKeys {
if _, ok := counts[key]; ok {
gauges["count"].With(mergeLabels(map[string]string{
"extension": key,
})).Set(float64(counts[key]))
gauges["size"].With(mergeLabels(map[string]string{
"extension": key,
})).Set(float64(sizes[key]))
continue
}
// Clean up extension which no longer exists in the directory
gauges["count"].Delete(mergeLabels(map[string]string{"extension": key}))
gauges["size"].Delete(mergeLabels(map[string]string{"extension": key}))
delete(extensionKeys, key)
}
}
func updateLoop() {
for range time.Tick(time.Duration(interval) * time.Second) {
update()
}
}
|
