feat: Add gz compression for html response

Pre-compress the HTML page to avoid slow page loads when more and/or high res images are added

cmd/main.go

@@ -4,17 +4,19 @@ import (
 	_ "embed"
 	"flag"
 	"github.com/timo-reymann/yal/pkg/buildinfo"
+	"github.com/timo-reymann/yal/pkg/compress"
 	"github.com/timo-reymann/yal/pkg/config"
 	"github.com/timo-reymann/yal/pkg/templating"
 	"log"
 	"net/http"
+	_ "net/http/pprof"
 	"os"
 )
 
-func renderTemplate(templateFile string) (string, error) {
+func renderTemplate(templateFile string) ([]byte, error) {
 	c, err := config.Load()
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 
 	return templating.RenderTemplate(templateFile, c)
@@ -46,7 +48,7 @@ func Run() {
 		log.Println("Rendering " + *renderOutput)
 
 		if *renderOutput == "-" {
-			_, _ = os.Stdout.WriteString(rendered)
+			_, _ = os.Stdout.Write(rendered)
 			return
 		}
 
@@ -56,16 +58,23 @@ func Run() {
 		}
 		defer templatedFile.Close()
 
-		_, err = templatedFile.WriteString(rendered)
+		_, err = templatedFile.Write(rendered)
 		if err != nil {
 			log.Fatalf("Failed to write templated content to file: %s", err.Error())
 		}
 	}
 
 	if *serve {
+		renderedGz, err := compress.GzBytes(rendered)
+		if err != nil {
+			log.Fatalf("Failed to compress HTML page for HTTP server: %s", err.Error())
+		}
+
 		log.Println("Starting server on 0.0.0.0:" + config.Port())
 		http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
-			_, _ = w.Write([]byte(rendered))
+			w.Header().Set("Content-Type", "text/html")
+			w.Header().Set("Content-Encoding", "gzip")
+			_, _ = w.Write(renderedGz)
 		})
 
 		log.Fatal(http.ListenAndServe(":"+config.Port(), nil))

pkg/compress/main.go

@@ -0,0 +1,19 @@
+package compress
+
+import (
+	"bytes"
+	"compress/gzip"
+)
+
+// GzBytes takes a given byte array and returns a compressed version using gz
+func GzBytes(data []byte) ([]byte, error) {
+	var renderedGzBuffer bytes.Buffer
+	gzw := gzip.NewWriter(&renderedGzBuffer)
+	if _, err := gzw.Write(data); err != nil {
+		return nil, err
+	}
+	gzd := renderedGzBuffer.Bytes()
+	renderedGzBuffer.Reset()
+
+	return gzd, nil
+}

pkg/compress/main_test.go

@@ -0,0 +1,32 @@
+package compress
+
+import (
+	"bytes"
+	"compress/gzip"
+	"testing"
+)
+
+func TestGzBytes(t *testing.T) {
+	// Test data
+	inputData := []byte("hello, world")
+
+	// Call the function
+	_, err := GzBytes(inputData)
+	if err != nil {
+		t.Fatalf("Expected gz compress to work for buffer, but failed: %v", err)
+	}
+}
+
+// Helper function to compress data using gzip
+func compressData(data []byte) ([]byte, error) {
+	var buf bytes.Buffer
+	gz := gzip.NewWriter(&buf)
+	_, err := gz.Write(data)
+	if err != nil {
+		return nil, err
+	}
+	if err := gz.Close(); err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}

pkg/templating/main.go

@@ -12,15 +12,15 @@ import (
 //go:embed index.gohtml
 var DefaultTemplate string
 
-func RenderTemplate(path string, c *config.Configuration) (string, error) {
+func RenderTemplate(path string, c *config.Configuration) ([]byte, error) {
 	var htmlFile []byte
 	var err error
 	if path == "builtin" {
 		htmlFile = []byte(DefaultTemplate)
 	} else {
 		htmlFile, err = os.ReadFile(path)
 		if err != nil {
-			return "", err
+			return nil, err
 		}
 	}
 
@@ -32,14 +32,14 @@ func RenderTemplate(path string, c *config.Configuration) (string, error) {
 	})
 	tmpl, err = tmpl.Parse(string(htmlFile))
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 
 	var outputBuffer bytes.Buffer
 	err = tmpl.Execute(&outputBuffer, c)
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 
-	return outputBuffer.String(), nil
+	return outputBuffer.Bytes(), nil
 }

pkg/templating/main_test.go

@@ -22,7 +22,7 @@ func TestRenderTemplate_Default(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if templated == "" {
+	if templated == nil {
 		t.Fatal("Expected template to be rendered for default")
 	}
 }
@@ -32,7 +32,7 @@ func TestRenderTemplate_DefaultFile(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if templated == "" {
+	if templated == nil {
 		t.Fatal("Expected template to be rendered for default")
 	}
 }