web: add option to serve live filesystem instead of embedded one

web/config.go

@@ -4,6 +4,8 @@ package web
 type Configuration struct {
 	// GrafanaURL is the URL to acess Grafana.
 	GrafanaURL string
+	// ServeLiveFS serve files from the filesystem instead of the embedded versions.
+	ServeLiveFS bool
 }
 
 // DefaultConfiguration represents the default configuration for the web exporter.

web/root.go

@@ -9,6 +9,10 @@ import (
 	netHTTP "net/http"
 	"net/http/httputil"
 	"net/url"
+	"os"
+	"path"
+	"path/filepath"
+	"runtime"
 
 	"akvorado/http"
 	"akvorado/reporter"
@@ -38,11 +42,20 @@ func New(reporter *reporter.Reporter, config Configuration, dependencies Depende
 		d:      &dependencies,
 		config: config,
 	}
-	data, err := fs.Sub(rootSite, "data")
-	if err != nil {
-		return nil, fmt.Errorf("unable to get embedded website: %w", err)
+
+	var data fs.FS
+	if config.ServeLiveFS {
+		_, src, _, _ := runtime.Caller(0)
+		data = os.DirFS(filepath.Join(path.Dir(src), "data"))
+	} else {
+		var err error
+		data, err = fs.Sub(rootSite, "data")
+		if err != nil {
+			return nil, fmt.Errorf("unable to get embedded website: %w", err)
+		}
 	}
 	c.d.HTTP.AddHandler("/", netHTTP.FileServer(netHTTP.FS(data)))
+
 	if c.config.GrafanaURL != "" {
 		// Provide a proxy for Grafana
 		url, err := url.Parse(config.GrafanaURL)
@@ -63,5 +76,6 @@ func New(reporter *reporter.Reporter, config Configuration, dependencies Depende
 			})
 		c.d.HTTP.AddHandler("/grafana/", proxyHandler)
 	}
+
 	return &c, nil
 }

web/root_test.go

@@ -47,3 +47,31 @@ func TestProxy(t *testing.T) {
 		t.Errorf("GET /grafana/test (-got, +want):\n%s", diff)
 	}
 }
+
+func TestStaticFiles(t *testing.T) {
+	for _, live := range []bool{false, true} {
+		name := "livefs"
+		if !live {
+			name = "embeddedfs"
+		}
+		t.Run(name, func(t *testing.T) {
+			r := reporter.NewMock(t)
+			h := http.NewMock(t, r)
+			_, err := New(r, Configuration{
+				ServeLiveFS: live,
+			}, Dependencies{HTTP: h})
+			if err != nil {
+				t.Fatalf("New() error:\n%+v", err)
+			}
+
+			resp, err := netHTTP.Get(fmt.Sprintf("http://%s/install.html", h.Address))
+			if err != nil {
+				t.Fatalf("GET /install.html:\n%+v", err)
+			}
+			defer resp.Body.Close()
+			if resp.StatusCode != 200 {
+				t.Errorf("GET /install.html: got status code %d, not 200", resp.StatusCode)
+			}
+		})
+	}
+}