From d682220305a07d2fa31825a4d377d20eb0e1f1fb Mon Sep 17 00:00:00 2001
From: Jakob Borg <jakob@kastelo.net>
Date: Sun, 10 Aug 2025 21:14:25 +0200
Subject: [PATCH] chore: remove GUI "debugging" toggle, debug HTTP metrics
 (#10235)

This removes the `debugging` bool under GUI configuration, and two no
longer relevant development endpoints: `httpmetrics` (which I can't
imagine anyone using for anything -- if we need such metrics today, the
right place is the Prometheus exported metrics) and the `peerCompletion`
endpoint (previously used by integration tests).

The debugging bool initially enabled just those two endpoints, which are
not for end users. Then we added profiling and support bundles, which
are very useful indeed for end users to access, and they were hidden
behind the same debug flag. I don't see any reason for keeping that flag
now that these methods are more generally useful.

https://github.com/syncthing/docs/pull/949
---
 gui/default/index.html         | 11 +++--
 lib/api/api.go                 | 79 +---------------------------------
 lib/config/guiconfiguration.go |  1 -
 lib/ur/usage_report.go         |  3 --
 test/h1/config.xml             |  2 +-
 test/h2/config.xml             |  2 +-
 6 files changed, 9 insertions(+), 89 deletions(-)

diff --git a/gui/default/index.html b/gui/default/index.html
index bb072f1ea..4a59693df 100644
--- a/gui/default/index.html
+++ b/gui/default/index.html
@@ -108,7 +108,7 @@
               <li><a href="" ng-click="about.show()"><span class="fa fa-fw fa-heart"></span>&nbsp;<span translate>About</span></a></li>
             </ul>
           </li>
-          <li ng-if="authenticated || config.gui.debugging" class="dropdown action-menu">
+          <li ng-if="authenticated" class="dropdown action-menu">
             <a href="#" class="dropdown-toggle" data-toggle="dropdown" aria-expanded="false">
               <span class="fa fa-cog"></span>
               <span class="hidden-xs" translate>Actions</span>
@@ -116,14 +116,13 @@
             </a>
             <ul class="dropdown-menu">
               <li ng-if="authenticated"><a href="" ng-click="showSettings()"><span class="fa fa-fw fa-cog"></span>&nbsp;<span translate>Settings</span></a></li>
-              <li ng-if="authenticated"><a href="" ng-click="showDeviceIdentification(thisDevice())"><span class="fa fa-fw fa-qrcode"></span>&nbsp;<span translate>Show ID</span></a></li>
+              <li ng-if="authenticated"><a href="" ng-click="advanced()"><span class="fa fa-fw fa-cogs"></span>&nbsp;<span translate>Advanced</span></a></li>
 
               <li ng-if="authenticated" class="divider" aria-hidden="true"></li>
-              <li ng-if="authenticated"><a href="" ng-click="advanced()"><span class="fa fa-fw fa-cogs"></span>&nbsp;<span translate>Advanced</span></a></li>
-              <li ng-if="authenticated"><a href="" ng-click="logging.show()"><span class="fa fa-fw fa-wrench"></span>&nbsp;<span translate>Logs</span></a></li>
 
-              <li class="divider" aria-hidden="true" ng-if="config.gui.debugging"></li>
-              <li><a href="/rest/debug/support" target="_blank" ng-if="config.gui.debugging"><span class="fa fa-fw fa-user-md"></span>&nbsp;<span translate>Support Bundle</span></a></li>
+              <li ng-if="authenticated"><a href="" ng-click="showDeviceIdentification(thisDevice())"><span class="fa fa-fw fa-qrcode"></span>&nbsp;<span translate>Show ID</span></a></li>
+              <li ng-if="authenticated"><a href="" ng-click="logging.show()"><span class="fa fa-fw fa-wrench"></span>&nbsp;<span translate>Logs</span></a></li>
+              <li ng-if="authenticated"><a href="/rest/debug/support" target="_blank"><span class="fa fa-fw fa-user-md"></span>&nbsp;<span translate>Support Bundle</span></a></li>
 
               <li ng-if="authenticated" class="divider" aria-hidden="true"></li>
               <li ng-if="authenticated && isAuthEnabled()"><a href="" ng-click="logout()"><span class="far fa-fw fa-sign-out"></span>&nbsp;<span translate>Log Out</span></a></li>
diff --git a/lib/api/api.go b/lib/api/api.go
index a13d9d10d..e77378077 100644
--- a/lib/api/api.go
+++ b/lib/api/api.go
@@ -36,7 +36,6 @@ import (
 	"github.com/calmh/incontainer"
 	"github.com/julienschmidt/httprouter"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
-	"github.com/rcrowley/go-metrics"
 	"github.com/thejerf/suture/v4"
 	"github.com/vitrun/qart/qr"
 	"golang.org/x/text/runes"
@@ -336,16 +335,14 @@ func (s *service) Serve(ctx context.Context) error {
 
 	// Debug endpoints, not for general use
 	debugMux := http.NewServeMux()
-	debugMux.HandleFunc("/rest/debug/peerCompletion", s.getPeerCompletion)
-	debugMux.HandleFunc("/rest/debug/httpmetrics", s.getSystemHTTPMetrics)
 	debugMux.HandleFunc("/rest/debug/cpuprof", s.getCPUProf) // duration
 	debugMux.HandleFunc("/rest/debug/heapprof", s.getHeapProf)
 	debugMux.HandleFunc("/rest/debug/support", s.getSupportBundle)
 	debugMux.HandleFunc("/rest/debug/file", s.getDebugFile)
-	restMux.Handler(http.MethodGet, "/rest/debug/*method", s.whenDebugging(debugMux))
+	restMux.Handler(http.MethodGet, "/rest/debug/*method", debugMux)
 
 	// A handler that disables caching
-	noCacheRestMux := noCacheMiddleware(metricsMiddleware(restMux))
+	noCacheRestMux := noCacheMiddleware(restMux)
 
 	// The main routing handler
 	mux := http.NewServeMux()
@@ -489,9 +486,6 @@ func (*service) VerifyConfiguration(_, to config.Configuration) error {
 }
 
 func (s *service) CommitConfiguration(from, to config.Configuration) bool {
-	// No action required when this changes, so mask the fact that it changed at all.
-	from.GUI.Debugging = to.GUI.Debugging
-
 	if to.GUI == from.GUI {
 		// No GUI changes, we're done here.
 		return true
@@ -594,15 +588,6 @@ func corsMiddleware(next http.Handler, allowFrameLoading bool) http.Handler {
 	})
 }
 
-func metricsMiddleware(h http.Handler) http.Handler {
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		t := metrics.GetOrRegisterTimer(r.URL.Path, nil)
-		t0 := time.Now()
-		h.ServeHTTP(w, r)
-		t.UpdateSince(t0)
-	})
-}
-
 func redirectToHTTPSMiddleware(h http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if r.TLS == nil {
@@ -644,17 +629,6 @@ func localhostMiddleware(h http.Handler) http.Handler {
 	})
 }
 
-func (s *service) whenDebugging(h http.Handler) http.Handler {
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		if s.cfg.GUI().Debugging {
-			h.ServeHTTP(w, r)
-			return
-		}
-
-		http.Error(w, "Debugging disabled", http.StatusForbidden)
-	})
-}
-
 func (s *service) getPendingDevices(w http.ResponseWriter, _ *http.Request) {
 	devices, err := s.model.PendingDevices()
 	if err != nil {
@@ -1284,26 +1258,6 @@ func (s *service) getSupportBundle(w http.ResponseWriter, r *http.Request) {
 	io.Copy(w, &zipFilesBuffer)
 }
 
-func (*service) getSystemHTTPMetrics(w http.ResponseWriter, _ *http.Request) {
-	stats := make(map[string]interface{})
-	metrics.Each(func(name string, intf interface{}) {
-		if m, ok := intf.(*metrics.StandardTimer); ok {
-			pct := m.Percentiles([]float64{0.50, 0.95, 0.99})
-			for i := range pct {
-				pct[i] /= 1e6 // ns to ms
-			}
-			stats[name] = map[string]interface{}{
-				"count":         m.Count(),
-				"sumMs":         m.Sum() / 1e6, // ns to ms
-				"ratesPerS":     []float64{m.Rate1(), m.Rate5(), m.Rate15()},
-				"percentilesMs": pct,
-			}
-		}
-	})
-	bs, _ := json.MarshalIndent(stats, "", "  ")
-	w.Write(bs)
-}
-
 func (s *service) getSystemDiscovery(w http.ResponseWriter, _ *http.Request) {
 	devices := make(map[string]discover.CacheEntry)
 
@@ -1628,35 +1582,6 @@ func (*service) getQR(w http.ResponseWriter, r *http.Request) {
 	w.Write(code.PNG())
 }
 
-func (s *service) getPeerCompletion(w http.ResponseWriter, _ *http.Request) {
-	tot := map[string]float64{}
-	count := map[string]float64{}
-
-	for _, folder := range s.cfg.Folders() {
-		for _, device := range folder.DeviceIDs() {
-			deviceStr := device.String()
-			if s.model.ConnectedTo(device) {
-				comp, err := s.model.Completion(device, folder.ID)
-				if err != nil {
-					http.Error(w, err.Error(), http.StatusInternalServerError)
-					return
-				}
-				tot[deviceStr] += comp.CompletionPct
-			} else {
-				tot[deviceStr] = 0
-			}
-			count[deviceStr]++
-		}
-	}
-
-	comp := map[string]int{}
-	for device := range tot {
-		comp[device] = int(tot[device] / count[device])
-	}
-
-	sendJSON(w, comp)
-}
-
 func (s *service) getFolderVersions(w http.ResponseWriter, r *http.Request) {
 	qs := r.URL.Query()
 	versions, err := s.model.GetFolderVersions(qs.Get("folder"))
diff --git a/lib/config/guiconfiguration.go b/lib/config/guiconfiguration.go
index a38c7652c..2be127198 100644
--- a/lib/config/guiconfiguration.go
+++ b/lib/config/guiconfiguration.go
@@ -30,7 +30,6 @@ type GUIConfiguration struct {
 	APIKey                    string   `json:"apiKey" xml:"apikey,omitempty"`
 	InsecureAdminAccess       bool     `json:"insecureAdminAccess" xml:"insecureAdminAccess,omitempty"`
 	Theme                     string   `json:"theme" xml:"theme" default:"default"`
-	Debugging                 bool     `json:"debugging" xml:"debugging,attr"`
 	InsecureSkipHostCheck     bool     `json:"insecureSkipHostcheck" xml:"insecureSkipHostcheck,omitempty"`
 	InsecureAllowFrameLoading bool     `json:"insecureAllowFrameLoading" xml:"insecureAllowFrameLoading,omitempty"`
 	SendBasicAuthPrompt       bool     `json:"sendBasicAuthPrompt" xml:"sendBasicAuthPrompt,attr"`
diff --git a/lib/ur/usage_report.go b/lib/ur/usage_report.go
index d0ed2657a..f60dfd4b2 100644
--- a/lib/ur/usage_report.go
+++ b/lib/ur/usage_report.go
@@ -308,9 +308,6 @@ func (s *Service) reportData(ctx context.Context, urVersion int, preview bool) (
 			if guiCfg.InsecureAdminAccess {
 				report.GUIStats.InsecureAdminAccess++
 			}
-			if guiCfg.Debugging {
-				report.GUIStats.Debugging++
-			}
 			if guiCfg.InsecureSkipHostCheck {
 				report.GUIStats.InsecureSkipHostCheck++
 			}
diff --git a/test/h1/config.xml b/test/h1/config.xml
index c71d4cbd5..40a8c947d 100644
--- a/test/h1/config.xml
+++ b/test/h1/config.xml
@@ -65,7 +65,7 @@
         <remoteGUIPort>0</remoteGUIPort>
         <numConnections>3</numConnections>
     </device>
-    <gui enabled="true" tls="false" debugging="true" sendBasicAuthPrompt="false">
+    <gui enabled="true" tls="false" sendBasicAuthPrompt="false">
         <address>127.0.0.1:8081</address>
         <user>testuser</user>
         <password>$2a$10$7tKL5uvLDGn5s2VLPM2yWOK/II45az0mTel8hxAUJDRQN1Tk2QYwu</password>
diff --git a/test/h2/config.xml b/test/h2/config.xml
index 4cfcc661b..e91d6d633 100644
--- a/test/h2/config.xml
+++ b/test/h2/config.xml
@@ -65,7 +65,7 @@
         <remoteGUIPort>0</remoteGUIPort>
         <numConnections>3</numConnections>
     </device>
-    <gui enabled="true" tls="false" debugging="true" sendBasicAuthPrompt="false">
+    <gui enabled="true" tls="false" sendBasicAuthPrompt="false">
         <address>127.0.0.1:8082</address>
         <metricsWithoutAuth>false</metricsWithoutAuth>
         <apikey>abc123</apikey>