agent/proxy: implement force kill of unresponsive proxy process

agent/proxy/daemon.go

@@ -38,10 +38,15 @@ type Daemon struct {
 	// a file.
 	Logger *log.Logger
 
+	// For tests, they can set this to change the default duration to wait
+	// for a graceful quit.
+	gracefulWait time.Duration
+
 	// process is the started process
 	lock     sync.Mutex
 	stopped  bool
 	stopCh   chan struct{}
+	exitedCh chan struct{}
 	process  *os.Process
 }
 
@@ -64,17 +69,21 @@ func (p *Daemon) Start() error {
 
 	// Setup our stop channel
 	stopCh := make(chan struct{})
+	exitedCh := make(chan struct{})
 	p.stopCh = stopCh
+	p.exitedCh = exitedCh
 
 	// Start the loop.
-	go p.keepAlive(stopCh)
+	go p.keepAlive(stopCh, exitedCh)
 
 	return nil
 }
 
 // keepAlive starts and keeps the configured process alive until it
 // is stopped via Stop.
-func (p *Daemon) keepAlive(stopCh <-chan struct{}) {
+func (p *Daemon) keepAlive(stopCh <-chan struct{}, exitedCh chan<- struct{}) {
+	defer close(exitedCh)
+
 	p.lock.Lock()
 	process := p.process
 	p.lock.Unlock()
@@ -196,24 +205,42 @@ func (p *Daemon) start() (*os.Process, error) {
 // then this returns no error.
 func (p *Daemon) Stop() error {
 	p.lock.Lock()
-	defer p.lock.Unlock()
 
 	// If we're already stopped or never started, then no problem.
 	if p.stopped || p.process == nil {
 		// In the case we never even started, calling Stop makes it so
 		// that we can't ever start in the future, either, so mark this.
 		p.stopped = true
+		p.lock.Unlock()
 		return nil
 	}
 
 	// Note that we've stopped
 	p.stopped = true
 	close(p.stopCh)
+	process := p.process
+	p.lock.Unlock()
 
-	err := p.process.Signal(os.Interrupt)
+	gracefulWait := p.gracefulWait
+	if gracefulWait == 0 {
+		gracefulWait = 5 * time.Second
+	}
 
-	return err
+	// First, try a graceful stop
-	//return p.Command.Process.Kill()
+	err := process.Signal(os.Interrupt)
+	if err == nil {
+		select {
+		case <-p.exitedCh:
+			// Success!
+			return nil
+
+		case <-time.After(gracefulWait):
+			// Interrupt didn't work
+		}
+	}
+
+	// Graceful didn't work, forcibly kill
+	return process.Kill()
 }
 
 // Equal implements Proxy to check for equality.

agent/proxy/daemon_test.go

@@ -6,6 +6,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"testing"
+	"time"
 
 	"github.com/hashicorp/consul/testutil/retry"
 	"github.com/hashicorp/go-uuid"
@@ -99,6 +100,48 @@ func TestDaemonRestart(t *testing.T) {
 	waitFile()
 }
 
+func TestDaemonStop_kill(t *testing.T) {
+	t.Parallel()
+
+	require := require.New(t)
+	td, closer := testTempDir(t)
+	defer closer()
+
+	path := filepath.Join(td, "file")
+
+	d := &Daemon{
+		Command:      helperProcess("stop-kill", path),
+		ProxyToken:   "hello",
+		Logger:       testLogger,
+		gracefulWait: 200 * time.Millisecond,
+	}
+	require.NoError(d.Start())
+
+	// Wait for the file to exist
+	retry.Run(t, func(r *retry.R) {
+		_, err := os.Stat(path)
+		if err == nil {
+			return
+		}
+
+		r.Fatalf("error: %s", err)
+	})
+
+	// Stop the process
+	require.NoError(d.Stop())
+
+	// State the file so that we can get the mtime
+	fi, err := os.Stat(path)
+	require.NoError(err)
+	mtime := fi.ModTime()
+
+	// The mtime shouldn't change
+	time.Sleep(100 * time.Millisecond)
+	fi, err = os.Stat(path)
+	require.NoError(err)
+	require.Equal(mtime, fi.ModTime())
+}
+
 func TestDaemonEqual(t *testing.T) {
 	cases := []struct {
 		Name     string

agent/proxy/proxy_test.go

@@ -120,6 +120,24 @@ func TestHelperProcess(t *testing.T) {
 			}
 		}
 
+	case "stop-kill":
+		// Setup listeners so it is ignored
+		ch := make(chan os.Signal, 1)
+		signal.Notify(ch, os.Interrupt)
+		defer signal.Stop(ch)
+
+		path := args[0]
+		data := []byte(os.Getenv(EnvProxyToken))
+		for {
+			if err := ioutil.WriteFile(path, data, 0644); err != nil {
+				t.Fatalf("err: %s", err)
+			}
+			time.Sleep(25 * time.Millisecond)
+		}
+
+		// Run forever
+		<-make(chan struct{})
+
 	default:
 		fmt.Fprintf(os.Stderr, "Unknown command: %q\n", cmd)
 		os.Exit(2)