control/controlclient,health: add tests for control health tracking

Updates tailscale/corp#27759

Signed-off-by: James Sanderson <jsanderson@tailscale.com>

control/controlclient/map_test.go

@@ -17,6 +17,7 @@ import (
 	"github.com/google/go-cmp/cmp"
 	"go4.org/mem"
 	"tailscale.com/control/controlknobs"
+	"tailscale.com/health"
 	"tailscale.com/tailcfg"
 	"tailscale.com/tstest"
 	"tailscale.com/tstime"
@@ -1136,3 +1137,34 @@ func BenchmarkMapSessionDelta(b *testing.B) {
 		})
 	}
 }
+
+// TestNetmapHealthIntegration checks that we get the expected health warnings
+// from processing a map response and passing the NetworkMap to a health tracker
+func TestNetmapHealthIntegration(t *testing.T) {
+	ms := newTestMapSession(t, nil)
+	ht := health.Tracker{}
+
+	ht.SetIPNState("NeedsLogin", true)
+	ht.GotStreamedMapResponse()
+
+	nm := ms.netmapForResponse(&tailcfg.MapResponse{
+		Health: []string{"Test message"},
+	})
+	ht.SetControlHealth(nm.ControlHealth)
+
+	state := ht.CurrentState()
+	warning, ok := state.Warnings["control-health"]
+
+	if !ok {
+		t.Fatal("no warning found in current state with code 'control-health'")
+	}
+	if got, want := warning.Title, "Coordination server reports an issue"; got != want {
+		t.Errorf("warning.Title = %q, want %q", got, want)
+	}
+	if got, want := warning.Severity, health.SeverityMedium; got != want {
+		t.Errorf("warning.Severity = %s, want %s", got, want)
+	}
+	if got, want := warning.Text, "The coordination server is reporting an health issue: Test message"; got != want {
+		t.Errorf("warning.Text = %q, want %q", got, want)
+	}
+}

health/health.go

@@ -402,7 +402,7 @@ func (t *Tracker) setUnhealthyLocked(w *Warnable, args Args) {
 			// executed immediately. Otherwise, the callback should be enqueued to run once the Warnable
 			// becomes visible.
 			if w.IsVisible(ws, t.now) {
-				go cb(w, w.unhealthyState(ws))
+				cb(w, w.unhealthyState(ws))
 				continue
 			}
 
@@ -415,7 +415,7 @@ func (t *Tracker) setUnhealthyLocked(w *Warnable, args Args) {
 				// Check if the Warnable is still unhealthy, as it could have become healthy between the time
 				// the timer was set for and the time it was executed.
 				if t.warnableVal[w] != nil {
-					go cb(w, w.unhealthyState(ws))
+					cb(w, w.unhealthyState(ws))
 					delete(t.pendingVisibleTimers, w)
 				}
 			})
@@ -449,7 +449,7 @@ func (t *Tracker) setHealthyLocked(w *Warnable) {
 	}
 
 	for _, cb := range t.watchers {
-		go cb(w, nil)
+		cb(w, nil)
 	}
 }
 
@@ -483,6 +483,16 @@ func (t *Tracker) AppendWarnableDebugFlags(base []string) []string {
 // The provided callback function will be executed in its own goroutine. The returned function can be used
 // to unregister the callback.
 func (t *Tracker) RegisterWatcher(cb func(w *Warnable, r *UnhealthyState)) (unregister func()) {
+	return t.registerSyncWatcher(func(w *Warnable, r *UnhealthyState) {
+		go cb(w, r)
+	})
+}
+
+// registerSyncWatcher adds a function that will be called whenever the health
+// state of any Warnable changes. The provided callback function will be
+// executed synchronously. Call RegisterWatcher to register any callbacks that
+// won't return from execution immediately.
+func (t *Tracker) registerSyncWatcher(cb func(w *Warnable, r *UnhealthyState)) (unregister func()) {
 	if t.nil() {
 		return func() {}
 	}

health/health_test.go

@@ -451,3 +451,88 @@ func TestNoDERPHomeWarnableManual(t *testing.T) {
 		t.Fatalf("got unexpected noDERPHomeWarnable warnable: %v", ws)
 	}
 }
+
+func TestControlHealth(t *testing.T) {
+	ht := Tracker{}
+	ht.SetIPNState("NeedsLogin", true)
+	ht.GotStreamedMapResponse()
+
+	ht.SetControlHealth([]string{"Test message"})
+	state := ht.CurrentState()
+	warning, ok := state.Warnings["control-health"]
+
+	if !ok {
+		t.Fatal("no warning found in current state with code 'control-health'")
+	}
+	if got, want := warning.Title, "Coordination server reports an issue"; got != want {
+		t.Errorf("warning.Title = %q, want %q", got, want)
+	}
+	if got, want := warning.Severity, SeverityMedium; got != want {
+		t.Errorf("warning.Severity = %s, want %s", got, want)
+	}
+	if got, want := warning.Text, "The coordination server is reporting an health issue: Test message"; got != want {
+		t.Errorf("warning.Text = %q, want %q", got, want)
+	}
+}
+
+func TestControlHealthNotifiesOnChange(t *testing.T) {
+	ht := Tracker{}
+	ht.SetIPNState("NeedsLogin", true)
+	ht.GotStreamedMapResponse()
+
+	gotNotified := false
+	ht.registerSyncWatcher(func(_ *Warnable, _ *UnhealthyState) {
+		gotNotified = true
+	})
+
+	ht.SetControlHealth([]string{"Test message"})
+
+	if !gotNotified {
+		t.Errorf("watcher did not get called, want it to be called")
+	}
+}
+
+func TestControlHealthNoNotifyOnUnchanged(t *testing.T) {
+	ht := Tracker{}
+	ht.SetIPNState("NeedsLogin", true)
+	ht.GotStreamedMapResponse()
+
+	// Set up an existing control health issue
+	ht.SetControlHealth([]string{"Test message"})
+
+	// Now register our watcher
+	gotNotified := false
+	ht.registerSyncWatcher(func(_ *Warnable, _ *UnhealthyState) {
+		gotNotified = true
+	})
+
+	// Send the same control health message again - should not notify
+	ht.SetControlHealth([]string{"Test message"})
+
+	if gotNotified {
+		t.Errorf("watcher got called, want it to not be called")
+	}
+}
+
+func TestControlHealthIgnoredOutsideMapPoll(t *testing.T) {
+	ht := Tracker{}
+	ht.SetIPNState("NeedsLogin", true)
+
+	gotNotified := false
+	ht.registerSyncWatcher(func(_ *Warnable, _ *UnhealthyState) {
+		gotNotified = true
+	})
+
+	ht.SetControlHealth([]string{"Test message"})
+
+	state := ht.CurrentState()
+	_, ok := state.Warnings["control-health"]
+
+	if ok {
+		t.Error("got a warning with code 'control-health', want none")
+	}
+
+	if gotNotified {
+		t.Error("watcher got called, want it to not be called")
+	}
+}