✨ Add support for controller-manager webhook shutdown delay

pkg/manager/signals/signal.go

@@ -20,26 +20,45 @@ import (
 	"context"
 	"os"
 	"os/signal"
+	"time"
 )
 
-var onlyOneSignalHandler = make(chan struct{})
+var (
+	onlyOneSignalHandler = make(chan struct{})
+	// Define global signal channel for testing
+	signalCh = make(chan os.Signal, 2)
+)
 
-// SetupSignalHandler registers for SIGTERM and SIGINT. A context is returned
-// which is canceled on one of these signals. If a second signal is caught, the program
-// is terminated with exit code 1.
-func SetupSignalHandler() context.Context {
+// SetupSignalHandlerWithDelay registers for SIGTERM and SIGINT. A context is
+// returned which is canceled on one of these signals after waiting for the
+// specified delay. In particular, the delay can be used to give external
+// Kubernetes controllers (such as kube-proxy) time to observe the termination
+// of this manager before starting shutdown of any webhook servers to avoid
+// receiving connection attempts after closing webhook listeners. If a second
+// signal is caught, the program is terminated with exit code 1.
+func SetupSignalHandlerWithDelay(delay time.Duration) context.Context {
 	close(onlyOneSignalHandler) // panics when called twice
 
 	ctx, cancel := context.WithCancel(context.Background())
 
-	c := make(chan os.Signal, 2)
-	signal.Notify(c, shutdownSignals...)
+	signal.Notify(signalCh, shutdownSignals...)
 	go func() {
-		<-c
-		cancel()
-		<-c
+		<-signalCh
+		// Cancel the context after delaying for the specified duration but
+		// avoid blocking if a second signal is caught
+		go func() {
+			<-time.After(delay)
+			cancel()
+		}()
+		<-signalCh
 		os.Exit(1) // second signal. Exit directly.
 	}()
 
 	return ctx
 }
+
+// SetupSignalHandler is a special case of SetupSignalHandlerWithDelay with no
+// delay for backwards compatibility
+func SetupSignalHandler() context.Context {
+	return SetupSignalHandlerWithDelay(time.Duration(0))
+}

pkg/manager/signals/signal_test.go

@@ -17,10 +17,7 @@ limitations under the License.
 package signals
 
 import (
-	"fmt"
 	"os"
-	"os/signal"
-	"sync"
 	"time"
 
 	. "github.com/onsi/ginkgo/v2"
@@ -31,53 +28,23 @@ var _ = Describe("runtime signal", func() {
 
 	Context("SignalHandler Test", func() {
 
-		It("test signal handler", func() {
-			ctx := SetupSignalHandler()
-			task := &Task{
-				ticker: time.NewTicker(time.Second * 2),
-			}
-			c := make(chan os.Signal, 1)
-			signal.Notify(c, os.Interrupt)
-			task.wg.Add(1)
-			go func(c chan os.Signal) {
-				defer task.wg.Done()
-				task.Run(c)
-			}(c)
+		It("test signal handler with delay", func() {
+			delay := time.Second
+			ctx := SetupSignalHandlerWithDelay(delay)
 
-			select {
-			case sig := <-c:
-				fmt.Printf("Got %s signal. Aborting...\n", sig)
-			case _, ok := <-ctx.Done():
-				Expect(ok).To(BeFalse())
-			}
+			// Save time before sending signal
+			beforeSendingSignal := time.Now()
+
+			// Send signal
+			signalCh <- os.Interrupt
+
+			_, ok := <-ctx.Done()
+			// Verify that the channel was closed
+			Expect(ok).To(BeFalse())
+			// Verify that our delay was respected
+			Expect(time.Since(beforeSendingSignal)).To(BeNumerically(">=", delay))
 		})
 
 	})
 
 })
-
-type Task struct {
-	wg     sync.WaitGroup
-	ticker *time.Ticker
-}
-
-func (t *Task) Run(c chan os.Signal) {
-	for {
-		go sendSignal(c)
-		handle()
-	}
-}
-
-func handle() {
-	for i := 0; i < 5; i++ {
-		fmt.Print("#")
-		time.Sleep(time.Millisecond * 100)
-	}
-	fmt.Println()
-}
-
-func sendSignal(stopChan chan os.Signal) {
-	fmt.Printf("...")
-	time.Sleep(1 * time.Second)
-	stopChan <- os.Interrupt
-}