Make timeouts and intervals configurable.

main.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"fmt"
 	"log/slog"
 	"net/http"
 	"os"
@@ -12,28 +11,44 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
-const (
-	fetchInterval = 120 * time.Second // time to sleep after every metrics fetch
-	updateTimeout = 90 * time.Second  // maximum time for metal-api to respond to all our requests
-)
-
 var (
 	client metalgo.Client
 )
 
 func main() {
+	envOrDefault := func(key, fallback string) string {
+		if val := os.Getenv(key); val != "" {
+			return val
+		}
+		return fallback
+	}
+
 	var (
 		log = slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{Level: slog.LevelInfo}))
 
-		url  = os.Getenv("METAL_API_URL")
-		hmac = os.Getenv("METAL_API_HMAC")
+		url              = os.Getenv("METAL_API_URL")
+		hmac             = os.Getenv("METAL_API_HMAC")
+		fetchIntervalEnv = envOrDefault("FETCH_INTERVAL", "90s") // time to sleep after every metrics fetch
+		updateTimeoutEnv = envOrDefault("UPDATE_TIMEOUT", "60s") // maximum time for metal-api to respond to all our requests until context gets cancelled
 
 		err error
 	)
 
 	client, err = metalgo.NewDriver(url, "", hmac)
 	if err != nil {
-		fmt.Print(err)
+		log.Error("error creating client", "error", err)
+		os.Exit(1)
+	}
+
+	fetchInterval, err := time.ParseDuration(fetchIntervalEnv)
+	if err != nil {
+		log.Error("error parsing fetch interval", "error", err)
+		os.Exit(1)
+	}
+
+	updateTimeout, err := time.ParseDuration(updateTimeoutEnv)
+	if err != nil {
+		log.Error("error parsing update timeout", "error", err)
 		os.Exit(1)
 	}
 
@@ -47,7 +62,7 @@ func main() {
 			log.Info("updating metrics...")
 			start := time.Now()
 
-			err = update()
+			err = update(updateTimeout)
 			if err != nil {
 				if !initialUpdateSuccess {
 					log.Error("error during initial update", "error", err)

metrics.go

@@ -21,7 +21,7 @@ import (
 	"golang.org/x/sync/errgroup"
 )
 
-func update() error {
+func update(updateTimeout time.Duration) error {
 	ctx, cancel := context.WithTimeout(context.Background(), updateTimeout)
 	defer cancel()