Decouple shared functions between controllers (#8829)

* Decouple shared functions between controllers

* Apply suggestions from code review

Co-authored-by: Jintao Zhang <tao12345666333@163.com>

* Fix package names and fmt

Co-authored-by: Jintao Zhang <tao12345666333@163.com>

pkg/util/process/controller.go

@@ -0,0 +1,24 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package process
+
+// ProcessController defines a common interface for a process to be controlled,
+// like the configurer, the webhook or the proper ingress controller
+type ProcessController interface {
+	Start()
+	Stop() error
+}

pkg/util/process/sigterm.go

@@ -0,0 +1,49 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package process
+
+import (
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	klog "k8s.io/klog/v2"
+)
+
+type exiter func(code int)
+
+// HandleSigterm receives a ProcessController interface and deals with
+// the graceful shutdown
+func HandleSigterm(ngx ProcessController, delay int, exit exiter) {
+	signalChan := make(chan os.Signal, 1)
+	signal.Notify(signalChan, syscall.SIGTERM)
+	<-signalChan
+	klog.InfoS("Received SIGTERM, shutting down")
+
+	exitCode := 0
+	if err := ngx.Stop(); err != nil {
+		klog.Warningf("Error during shutdown: %v", err)
+		exitCode = 1
+	}
+
+	klog.Infof("Handled quit, delaying controller exit for %d seconds", delay)
+	time.Sleep(time.Duration(delay) * time.Second)
+
+	klog.InfoS("Exiting", "code", exitCode)
+	exit(exitCode)
+}

pkg/util/process/sigterm_test.go

@@ -0,0 +1,79 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package process
+
+import (
+	"fmt"
+	"syscall"
+	"testing"
+	"time"
+)
+
+type FakeProcess struct {
+	shouldError bool
+	exitCode    int
+}
+
+func (f *FakeProcess) Start() {
+}
+
+func (f *FakeProcess) Stop() error {
+	if f.shouldError {
+		return fmt.Errorf("error")
+	}
+	return nil
+}
+
+func (f *FakeProcess) exiterFunc(code int) {
+	f.exitCode = code
+}
+
+func sendDelayedSignal(delay time.Duration) {
+	time.Sleep(delay * time.Second)
+	syscall.Kill(syscall.Getpid(), syscall.SIGTERM)
+}
+
+func TestHandleSigterm(t *testing.T) {
+	tests := []struct {
+		name        string
+		shouldError bool
+		delay       int
+	}{
+		{
+			name:        "should exit without error",
+			shouldError: false,
+		},
+		{
+			name:        "should exit with error",
+			shouldError: true,
+			delay:       2,
+		},
+	}
+	for _, tt := range tests {
+		process := &FakeProcess{shouldError: tt.shouldError}
+		t.Run(tt.name, func(t *testing.T) {
+			go sendDelayedSignal(2) // Send a signal after 2 seconds
+			HandleSigterm(process, tt.delay, process.exiterFunc)
+		})
+		if tt.shouldError && process.exitCode != 1 {
+			t.Errorf("wrong return, should be 1 and returned %d", process.exitCode)
+		}
+		if !tt.shouldError && process.exitCode != 0 {
+			t.Errorf("wrong return, should be 0 and returned %d", process.exitCode)
+		}
+	}
+}