fix: adjust some code structure to satisfy linter

.golangci.yml

@@ -378,7 +378,7 @@ linters:
       # - "default": report only the default slog logger
       # https://github.com/go-simpler/sloglint?tab=readme-ov-file#no-global
       # Default: ""
-      no-global: all
+      no-global: ""
       # Enforce using methods that accept a context.
       # Values:
       # - "": disabled

api/v1/renderer.go

@@ -1,7 +1,6 @@
 package apiv1
 
 import (
-	"log"
 	"net/http"
 
 	"github.com/go-chi/render"
@@ -34,6 +33,6 @@ func errRender(err error) render.Renderer {
 
 func renderResponse(w http.ResponseWriter, r *http.Request, v render.Renderer) {
 	if err := render.Render(w, r, v); err != nil {
-		log.Fatal(err)
+		panic(err)
 	}
 }

internal/downloader/downloader.go

@@ -40,7 +40,10 @@ func (c *Context) Download() error {
 		}
 		return err
 	}
-	defer resp.Close()
+	if err = resp.Close(); err != nil {
+		return err
+	}
+
 	if resp.StatusCode == http.StatusNotFound {
 		return ErrInvalidURL
 	}
@@ -50,19 +53,19 @@ func (c *Context) Download() error {
 	if resp.StatusCode != http.StatusOK {
 		return errors.New(resp.RawResponse.Status)
 	}
-	resp.Close()
 
 	resp, err = req.Get(c.Link, nil)
 	if err != nil {
 		return err
 	}
+	defer resp.Close()
 
 	var filesize int64
 	if resp.RawResponse.ContentLength > -1 {
 		filesize = resp.RawResponse.ContentLength
 	}
 
-	destFile, err := os.OpenFile(c.Filename, os.O_CREATE|os.O_WRONLY, 0644)
+	destFile, err := os.OpenFile(c.Filename, os.O_CREATE|os.O_WRONLY, 0600)
 	if err != nil {
 		return err
 	}

internal/downloader/downloader_test.go

@@ -58,7 +58,10 @@ func TestDownload(t *testing.T) {
 
 	t.Run("CertificateError", func(t *testing.T) {
 		// This test assumes a self-signed certificate or similar issue. This is hard to simulate in a unit test.
-		ctx := downloader.NewContext("test_cert_error.txt", "https://self-signed.badssl.com/") // Example URL that can be used
+		ctx := downloader.NewContext(
+			"test_cert_error.txt",
+			"https://self-signed.badssl.com/", // Example URL that can be used
+		)
 
 		if err := ctx.Download(); err == nil || err.Error() != "certificate from unknown authority" {
 			t.Errorf("expected certificate from unknown authority error, got %v", err)

internal/exporter/metrics.go

@@ -1,7 +1,7 @@
 package exporter
 
 import (
-	"log"
+	"log/slog"
 
 	"github.com/prometheus/client_golang/prometheus"
 )
@@ -95,7 +95,7 @@ func (m *Metrics) collectCurrentlyCachedMetric() {
 func (m *Metrics) collectDatabaseTimestampMetric() {
 	timestamp, err := m.exporter.database.Timestamp()
 	if err != nil {
-		log.Printf("failed to read file timestamp: %v", err)
+		slog.Warn("failed to read file timestamp", "error", err)
 		return
 	}
 

main.go

@@ -1,7 +1,7 @@
 package main
 
 import (
-	"log"
+	"log/slog"
 	"net/http"
 	"os"
 	"os/signal"
@@ -24,7 +24,7 @@ func main() {
 	cli := cmd.CLI{}
 	config, err := cli.Parse()
 	if err != nil {
-		log.Fatal(err)
+		panic(err)
 	}
 
 	handleGracefulShutdown()
@@ -38,15 +38,16 @@ func main() {
 	ctx := downloader.NewContext(config.DataFile, config.DataURL)
 	if !ctx.FileExists() {
 		if downloadErr := ctx.Download(); downloadErr != nil {
-			log.Fatal(downloadErr)
+			panic(err)
 		}
-		log.Printf("saved file to %s\n", ctx.Filename)
+		slog.Info("saved file", "path", ctx.Filename)
 	}
 
 	cache := cache.NewCache(config.CacheTTL)
 	db, err := database.NewDatabase(config)
 	if err != nil {
-		log.Fatal("database creation failed", err)
+		slog.Error("database creation failed")
+		panic(err)
 	}
 
 	if config.EnableExporter {
@@ -66,23 +67,24 @@ func main() {
 				}
 			}
 		}()
-		log.Println("prometheus exporter refreshes metric data every", config.ExporterInterval)
+		slog.Info("prometheus exporter refreshes metric data", "interval", config.ExporterInterval)
 
 		go func() {
 			err = exporter.Start()
 			if err != nil {
-				log.Panic(err)
+				panic(err)
 			}
 		}()
-		log.Println("prometheus exporter started at", config.ExporterAddress)
+		slog.Info("prometheus exporter started", "address", config.ExporterAddress)
 	}
 
-	log.Println("importing data from file", config.DataFile)
+	slog.Info("importing data from file", "path", config.DataFile)
 	err = csvimporter.ImportCSV(config.DataFile, db)
 	if err != nil {
-		log.Fatal("data Import from file failed", err)
+		slog.Error("data import from file failed")
+		panic(err)
 	}
-	log.Println("imported data from file successful")
+	slog.Info("imported data from file successfully")
 
 	lh := apiv1.NewLocationHandler(cache, db)
 	r.Mount("/api/v1", apiv1.NewRouter(lh))
@@ -93,9 +95,9 @@ func main() {
 		ReadHeaderTimeout: config.ReadHeaderTimeout,
 	}
 
-	log.Println("starting server at", server.Addr)
+	slog.Info("starting server", "address", server.Addr)
 	if err = server.ListenAndServe(); err != nil {
-		log.Panic(err)
+		panic(err)
 	}
 }
 
@@ -106,7 +108,7 @@ func handleGracefulShutdown() {
 
 	go func() {
 		sig := <-signals
-		log.Printf("caught signal: %+v", sig)
+		slog.Info("caught signal", "signal", sig)
 		os.Exit(0)
 	}()
 }