refactor: replace signal package by signal.NotifyContext (#4691)

Signed-off-by: Charles-Edouard Brétéché <charled.breteche@gmail.com>

Signed-off-by: Charles-Edouard Brétéché <charled.breteche@gmail.com>
Co-authored-by: Vyankatesh Kudtarkar <vyankateshkd@gmail.com>

cmd/initContainer/main.go

@@ -8,7 +8,9 @@ import (
 	"encoding/json"
 	"flag"
 	"os"
+	"os/signal"
 	"sync"
+	"syscall"
 	"time"
 
 	kyvernov1beta1 "github.com/kyverno/kyverno/api/kyverno/v1beta1"
@@ -17,7 +19,6 @@ import (
 	"github.com/kyverno/kyverno/pkg/config"
 	"github.com/kyverno/kyverno/pkg/leaderelection"
 	"github.com/kyverno/kyverno/pkg/policyreport"
-	"github.com/kyverno/kyverno/pkg/signal"
 	"github.com/kyverno/kyverno/pkg/tls"
 	"github.com/kyverno/kyverno/pkg/utils"
 	"go.uber.org/multierr"
@@ -75,7 +76,11 @@ func main() {
 	flag.Parse()
 
 	// os signal handler
-	stopCh := signal.SetupSignalHandler()
+	signalCtx, signalCancel := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer signalCancel()
+
+	stopCh := signalCtx.Done()
+
 	// create client config
 	clientConfig, err := config.CreateClientConfig(kubeconfig, clientRateLimitQPS, clientRateLimitBurst)
 	if err != nil {
@@ -118,11 +123,9 @@ func main() {
 		{convertGenerateRequest},
 	}
 
-	ctx, cancel := context.WithCancel(context.Background())
-
 	go func() {
+		defer signalCancel()
 		<-stopCh
-		cancel()
 	}()
 
 	addPolicyReportSelectorLabel(client)
@@ -151,7 +154,7 @@ func main() {
 			}
 		}
 
-		if err = acquireLeader(ctx, kubeClient); err != nil {
+		if err = acquireLeader(signalCtx, kubeClient); err != nil {
 			log.Log.V(2).Info("Failed to create lease 'kyvernopre-lock'")
 			os.Exit(1)
 		}
@@ -184,7 +187,7 @@ func main() {
 		os.Exit(1)
 	}
 
-	le.Run(ctx)
+	le.Run(signalCtx)
 }
 
 func acquireLeader(ctx context.Context, kubeClient kubernetes.Interface) error {

cmd/kyverno/main.go

@@ -8,7 +8,9 @@ import (
 	"net/http"
 	_ "net/http/pprof" // #nosec
 	"os"
+	"os/signal"
 	"strings"
+	"syscall"
 	"time"
 
 	"github.com/kyverno/kyverno/pkg/background"
@@ -29,7 +31,6 @@ import (
 	"github.com/kyverno/kyverno/pkg/policycache"
 	"github.com/kyverno/kyverno/pkg/policyreport"
 	"github.com/kyverno/kyverno/pkg/registryclient"
-	"github.com/kyverno/kyverno/pkg/signal"
 	"github.com/kyverno/kyverno/pkg/tls"
 	"github.com/kyverno/kyverno/pkg/toggle"
 	"github.com/kyverno/kyverno/pkg/tracing"
@@ -122,8 +123,12 @@ func main() {
 
 	version.PrintVersionInfo(log.Log)
 
+	// os signal handler
+	signalCtx, signalCancel := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer signalCancel()
+
 	cleanUp := make(chan struct{})
-	stopCh := signal.SetupSignalHandler()
+	stopCh := signalCtx.Done()
 	debug := serverIP != ""
 
 	// clients
@@ -422,14 +427,10 @@ func main() {
 		webhookCfg.UpdateWebhookChan <- true
 	}
 
-	// leader election context
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
 	// cancel leader election context on shutdown signals
 	go func() {
+		defer signalCancel()
 		<-stopCh
-		cancel()
 	}()
 
 	// webhookconfigurations are registered by the leader only
@@ -439,7 +440,7 @@ func main() {
 		os.Exit(1)
 	}
 
-	go webhookRegisterLeader.Run(ctx)
+	go webhookRegisterLeader.Run(signalCtx)
 
 	// the webhook server runs across all instances
 	openAPIController := startOpenAPIController(dynamicClient, stopCh)
@@ -519,7 +520,7 @@ func main() {
 	// start Kyverno controllers
 	go policyCacheController.Run(stopCh)
 	go urc.Run(genWorkers, stopCh)
-	go le.Run(ctx)
+	go le.Run(signalCtx)
 	go reportReqGen.Run(2, stopCh)
 	go configurationController.Run(stopCh)
 	go eventGenerator.Run(3, stopCh)

pkg/signal/signal.go

@@ -1,45 +0,0 @@
-package signal
-
-import (
-	"os"
-	"os/signal"
-)
-
-var (
-	onlyOneSignalHandler = make(chan struct{})
-	shutdownHandler      chan os.Signal
-)
-
-// SetupSignalHandler registered for SIGTERM and SIGINT. A stop channel is returned
-// which is closed on one of these signals. If a second signal is caught, the program
-// is terminated with exit code 1.
-func SetupSignalHandler() <-chan struct{} {
-	close(onlyOneSignalHandler) // panics when called twice
-
-	shutdownHandler = make(chan os.Signal, 2)
-
-	stop := make(chan struct{})
-	signal.Notify(shutdownHandler, shutdownSignals...)
-	go func() {
-		<-shutdownHandler
-		close(stop)
-		<-shutdownHandler
-		os.Exit(1) // second signal. Exit directly.
-	}()
-
-	return stop
-}
-
-// RequestShutdown emulates a received event that is considered as shutdown signal (SIGTERM/SIGINT)
-// This returns whether a handler was notified
-func RequestShutdown() bool {
-	if shutdownHandler != nil {
-		select {
-		case shutdownHandler <- shutdownSignals[0]:
-			return true
-		default:
-		}
-	}
-
-	return false
-}

pkg/signal/signal_posix.go

@@ -1,8 +0,0 @@
-package signal
-
-import (
-	"os"
-	"syscall"
-)
-
-var shutdownSignals = []os.Signal{os.Interrupt, syscall.SIGTERM}