Implement version check on load, if the footer has data-update-check=true,it fetches /api/version and sets the version badge. No request is made when update check is disabled.

pkg/web/handlers.go

@@ -50,6 +50,7 @@ import (
 	"github.com/swissmakers/fail2ban-ui/internal/fail2ban"
 	"github.com/swissmakers/fail2ban-ui/internal/integrations"
 	"github.com/swissmakers/fail2ban-ui/internal/storage"
+	"github.com/swissmakers/fail2ban-ui/internal/version"
 )
 
 // wsHub is the global WebSocket hub instance
@@ -1141,15 +1142,97 @@ func renderIndexPage(c *gin.Context) {
 		}
 	}
 
+	// Update check: default true; set UPDATE_CHECK=false to disable external GitHub request
+	updateCheckEnabled := os.Getenv("UPDATE_CHECK") != "false"
+
 	c.HTML(http.StatusOK, "index.html", gin.H{
-		"timestamp":         time.Now().Format(time.RFC1123),
-		"version":           time.Now().Unix(),
-		"disableExternalIP": disableExternalIP,
-		"oidcEnabled":       oidcEnabled,
-		"skipLoginPage":     skipLoginPage,
+		"timestamp":          time.Now().Format(time.RFC1123),
+		"version":            time.Now().Unix(),
+		"appVersion":         version.Version,
+		"updateCheckEnabled": updateCheckEnabled,
+		"disableExternalIP":  disableExternalIP,
+		"oidcEnabled":        oidcEnabled,
+		"skipLoginPage":      skipLoginPage,
 	})
 }
 
+// githubReleaseResponse is used to parse the GitHub releases/latest API response
+type githubReleaseResponse struct {
+	TagName string `json:"tag_name"`
+}
+
+// versionLess returns true if a < b (e.g. "1.3.5" < "1.3.6")
+func versionLess(a, b string) bool {
+	parse := func(s string) []int {
+		s = strings.TrimPrefix(strings.TrimSpace(s), "v")
+		parts := strings.Split(s, ".")
+		out := make([]int, 0, len(parts))
+		for _, p := range parts {
+			n, _ := strconv.Atoi(p)
+			out = append(out, n)
+		}
+		return out
+	}
+	pa, pb := parse(a), parse(b)
+	for i := 0; i < len(pa) || i < len(pb); i++ {
+		va, vb := 0, 0
+		if i < len(pa) {
+			va = pa[i]
+		}
+		if i < len(pb) {
+			vb = pb[i]
+		}
+		if va < vb {
+			return true
+		}
+		if va > vb {
+			return false
+		}
+	}
+	return false
+}
+
+// GetVersionHandler returns the current app version and optionally the latest GitHub release.
+// UPDATE_CHECK=false disables the external request to GitHub.
+func GetVersionHandler(c *gin.Context) {
+	updateCheckEnabled := os.Getenv("UPDATE_CHECK") != "false"
+	out := gin.H{
+		"version":              version.Version,
+		"update_check_enabled": updateCheckEnabled,
+	}
+	if !updateCheckEnabled {
+		c.JSON(http.StatusOK, out)
+		return
+	}
+	ctx, cancel := context.WithTimeout(c.Request.Context(), 8*time.Second)
+	defer cancel()
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, "https://api.github.com/repos/swissmakers/fail2ban-ui/releases/latest", nil)
+	if err != nil {
+		c.JSON(http.StatusOK, out)
+		return
+	}
+	req.Header.Set("Accept", "application/vnd.github.v3+json")
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		c.JSON(http.StatusOK, out)
+		return
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		c.JSON(http.StatusOK, out)
+		return
+	}
+	var gh githubReleaseResponse
+	if err := json.NewDecoder(resp.Body).Decode(&gh); err != nil {
+		c.JSON(http.StatusOK, out)
+		return
+	}
+	latest := strings.TrimPrefix(strings.TrimSpace(gh.TagName), "v")
+	out["latest_version"] = latest
+	out["update_available"] = versionLess(version.Version, latest)
+	c.JSON(http.StatusOK, out)
+}
+
 // GetJailFilterConfigHandler returns both the filter config and jail config for a given jail
 func GetJailFilterConfigHandler(c *gin.Context) {
 	config.DebugLog("----------------------------")

pkg/web/routes.go

@@ -58,6 +58,9 @@ func RegisterRoutes(r *gin.Engine, hub *Hub) {
 		api.POST("/jails", CreateJailHandler)
 		api.DELETE("/jails/:jail", DeleteJailHandler)
 
+		// Version and update check (only on page load; UPDATE_CHECK=false disables GitHub request)
+		api.GET("/version", GetVersionHandler)
+
 		// Settings endpoints
 		api.GET("/settings", GetSettingsHandler)
 		api.POST("/settings", UpdateSettingsHandler)

pkg/web/static/js/init.js

@@ -81,6 +81,26 @@ function initializeApp() {
       console.warn('Could not check LOTR on load:', err);
     });
   
+  // Version and update check: only on page load; UPDATE_CHECK=false disables external GitHub request
+  var versionContainer = document.getElementById('version-badge-container');
+  if (versionContainer && versionContainer.getAttribute('data-update-check') === 'true') {
+    fetch('/api/version')
+      .then(function(res) { return res.json(); })
+      .then(function(data) {
+        if (!data.update_check_enabled || versionContainer.innerHTML) return;
+        var latestLabel = typeof t === 'function' ? t('footer.latest', 'Latest') : 'Latest';
+        var updateHint = (typeof t === 'function' && translations && translations['footer.update_available'])
+          ? translations['footer.update_available'].replace('{version}', data.latest_version || '')
+          : ('Update available: v' + (data.latest_version || ''));
+        if (data.update_available && data.latest_version) {
+          versionContainer.innerHTML = '<a href="https://github.com/swissmakers/fail2ban-ui/releases" target="_blank" rel="noopener" class="inline-flex items-center px-2 py-0.5 rounded text-xs font-medium bg-amber-100 text-amber-800 hover:bg-amber-200" title="' + updateHint + '">' + updateHint + '</a>';
+        } else {
+          versionContainer.innerHTML = '<span class="inline-flex items-center px-2 py-0.5 rounded text-xs font-medium bg-green-100 text-green-800" title="' + latestLabel + '">' + latestLabel + '</span>';
+        }
+      })
+      .catch(function() { /* ignore; no badge on error */ });
+  }
+
   Promise.all([
     loadServers(),
     getTranslationsSettingsOnPageload()

pkg/web/templates/index.html

@@ -949,6 +949,8 @@
   <footer id="footer" class="hidden bg-gray-100 py-4">
     <div class="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8 text-center text-gray-600 text-sm">
       <p class="mb-0">
+        Fail2ban-UI v<span id="footer-app-version">{{.appVersion}}</span>
+        <span id="version-badge-container" class="ml-2" data-update-check="{{.updateCheckEnabled}}"></span>
         &copy; <a href="https://swissmakers.ch" target="_blank" class="text-blue-600 hover:text-blue-800">Swissmakers GmbH</a>
         -
         <a href="https://github.com/swissmakers/fail2ban-ui" target="_blank" class="text-blue-600 hover:text-blue-800">GitHub</a>