controller/engine: sync informers on controller start

Signed-off-by: Dr. Stefan Schimanski <stefan.schimanski@upbound.io>

pkg/controller/cache.go

@@ -147,8 +147,8 @@ func (c *GVKRoutedCache) Start(_ context.Context) error {
 	return nil
 }
 
-// WaitForCacheSync for a GVKRoutedCache waits for all delegates to sync, and
-// returns false if any of them fails to sync.
+// WaitForCacheSync for a GVKRoutedCache waits for all delegates and the
+// fallback to sync, and returns false if any of them fails to sync.
 func (c *GVKRoutedCache) WaitForCacheSync(ctx context.Context) bool {
 	c.lock.RLock()
 	syncedCh := make(chan bool, len(c.delegates)+1)
@@ -186,7 +186,7 @@ func (c *GVKRoutedCache) WaitForCacheSync(ctx context.Context) bool {
 		}
 	}
 
-	return true
+	return c.fallback.WaitForCacheSync(ctx)
 }
 
 // IndexField adds an index with the given field name on the given object type

pkg/controller/engine.go

@@ -271,6 +271,10 @@ func (c *namedController) Start(ctx context.Context) error {
 	}()
 	go func() {
 		<-c.e.mgr.Elected()
+		if synced := c.ca.WaitForCacheSync(ctx); !synced {
+			c.e.done(c.name, errors.New(errCrashCache))
+			return
+		}
 		c.e.done(c.name, errors.Wrap(c.ctrl.Start(ctx), errCrashController))
 	}()
 

pkg/controller/engine_test.go

@@ -47,6 +47,10 @@ func (c *MockCache) Start(stop context.Context) error {
 	return c.MockStart(stop)
 }
 
+func (c *MockCache) WaitForCacheSync(_ context.Context) bool {
+	return true
+}
+
 type MockController struct {
 	controller.Controller