add signals based on controller-runtime signals handler

signals/doc.go

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+/*
+Copyright 2017 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 signals contains libraries for handling signals to gracefully
+// shutdown the manager in combination with Kubernetes pod graceful termination
+// policy.
+package signals

signals/signal.go

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+/*
+Copyright 2017 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 signals
+
+import (
+	"context"
+	"os"
+	"os/signal"
+)
+
+var onlyOneSignalHandler = make(chan struct{})
+
+// 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 {
+	return SetupSignalHandlerWithContext(context.Background())
+}
+
+// SetupSignalHandlerWithContext registers for SIGTERM and SIGINT. A context using the
+// given context as parent 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 SetupSignalHandlerWithContext(ctx context.Context) context.Context {
+	close(onlyOneSignalHandler) // panics when called twice
+
+	ctx, cancel := context.WithCancel(ctx)
+
+	c := make(chan os.Signal, 2)
+	signal.Notify(c, shutdownSignals...)
+	go func() {
+		<-c
+		cancel()
+		<-c
+		os.Exit(1) // second signal. Exit directly.
+	}()
+
+	return ctx
+}

signals/signal_posix.go

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+// +build !windows
+
+/*
+Copyright 2017 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 signals
+
+import (
+	"os"
+	"syscall"
+)
+
+var shutdownSignals = []os.Signal{os.Interrupt, syscall.SIGTERM}

signals/signal_test.go

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+/*
+Copyright 2018 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 signals
+
+import (
+	"fmt"
+	"os"
+	"os/signal"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSignalsHandler(t *testing.T) {
+	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)
+
+	select {
+	case sig := <-c:
+		fmt.Printf("Got %s signal. Aborting...\n", sig)
+	case _, ok := <-ctx.Done():
+		assert.False(t, ok)
+	}
+}
+
+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
+}

signals/signal_windows.go

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+/*
+Copyright 2017 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 signals
+
+import (
+	"os"
+)
+
+var shutdownSignals = []os.Signal{os.Interrupt}