retry copy if copy receives EOF but still running

client/logmon/logmon.go

 package logmon
 
 import (
+	"context"
 	"fmt"
 	"io"
 	"os"
@@ -177,6 +178,8 @@ func NewTaskLogger(cfg *LogConfig, logger hclog.Logger) (*TaskLogger, error) {
 // log rotator data. The processOutWriter should be attached to the process and
 // data will be copied from the reader to the rotator.
 type logRotatorWrapper struct {
+	retryCtx          context.Context
+	retryCancel       context.CancelFunc
 	fifoPath          string
 	rotatorWriter     io.WriteCloser
 	hasFinishedCopied chan struct{}
@@ -217,8 +220,11 @@ func newLogRotatorWrapper(path string, logger hclog.Logger, rotator io.WriteClos
 		logger.Error("failed to create FIFO", "stat_error", serr, "create_err", err)
 		return nil, fmt.Errorf("failed to create fifo for extracting logs: %v", err)
 	}
+	ctx, cancel := context.WithCancel(context.Background())
 
 	wrap := &logRotatorWrapper{
+		retryCtx:          ctx,
+		retryCancel:       cancel,
 		fifoPath:          path,
 		rotatorWriter:     rotator,
 		hasFinishedCopied: make(chan struct{}),
@@ -235,6 +241,11 @@ func newLogRotatorWrapper(path string, logger hclog.Logger, rotator io.WriteClos
 func (l *logRotatorWrapper) start(openFn func() (io.ReadCloser, error)) {
 	go func() {
 		defer close(l.hasFinishedCopied)
+	RETRY_COPY:
+		if l.retryCtx.Err() != nil {
+			l.logger.Warn("fifo context cancelled, exiting")
+			return
+		}
 
 		reader, err := openFn()
 		if err != nil {
@@ -256,6 +267,21 @@ func (l *logRotatorWrapper) start(openFn func() (io.ReadCloser, error)) {
 			// force-killed.
 			reader.Close()
 		}
+		// Close reader
+		reader.Close()
+
+		// Check if the context has been closed
+		// return if it has, otherwise wait before
+		// restarting copy
+		select {
+		case <-l.retryCtx.Done():
+			return
+		case <-time.After(1 * time.Second):
+		}
+
+		// reset openCompleted
+		l.openCompleted = make(chan struct{})
+		goto RETRY_COPY
 	}()
 	return
 }
@@ -263,6 +289,9 @@ func (l *logRotatorWrapper) start(openFn func() (io.ReadCloser, error)) {
 // Close closes the rotator and the process writer to ensure that the Wait
 // command exits.
 func (l *logRotatorWrapper) Close() {
+	// Cancel the retryable context
+	l.retryCancel()
+
 	// Wait up to the close tolerance before we force close
 	select {
 	case <-l.hasFinishedCopied:

client/logmon/logmon_test.go

@@ -131,16 +131,10 @@ func TestLogmon_Start_restart_flusheslogs(t *testing.T) {
 	})
 	require.True(impl.tl.IsRunning())
 
-	// Close stdout and assert that logmon no longer writes to the file
+	// Close stdout and stderr
 	require.NoError(stdout.Close())
 	require.NoError(stderr.Close())
 
-	testutil.WaitForResult(func() (bool, error) {
-		return !impl.tl.IsRunning(), fmt.Errorf("logmon is still running")
-	}, func(err error) {
-		require.NoError(err)
-	})
-
 	stdout, err = fifo.OpenWriter(stdoutFifoPath)
 	require.NoError(err)
 	stderr, err = fifo.OpenWriter(stderrFifoPath)
@@ -234,16 +228,10 @@ func TestLogmon_Start_restart(t *testing.T) {
 	})
 	require.True(impl.tl.IsRunning())
 
-	// Close stdout and assert that logmon no longer writes to the file
+	// Close stdout and assert that logmon no longer writes to the fileA
 	require.NoError(stdout.Close())
 	require.NoError(stderr.Close())
 
-	testutil.WaitForResult(func() (bool, error) {
-		return !impl.tl.IsRunning(), fmt.Errorf("logmon is still running")
-	}, func(err error) {
-		require.NoError(err)
-	})
-
 	// Start logmon again and assert that it can receive logs again
 	require.NoError(lm.Start(cfg))
 
@@ -267,6 +255,74 @@ func TestLogmon_Start_restart(t *testing.T) {
 	})
 }
 
+// asserts that start goroutine properly exists when ctx is cancelled
+func TestLogmon_Start_restart_Close(t *testing.T) {
+	require := require.New(t)
+	var stdoutFifoPath, stderrFifoPath string
+
+	dir, err := ioutil.TempDir("", "nomadtest")
+	require.NoError(err)
+	defer os.RemoveAll(dir)
+
+	if runtime.GOOS == "windows" {
+		stdoutFifoPath = "//./pipe/test-restart.stdout"
+		stderrFifoPath = "//./pipe/test-restart.stderr"
+	} else {
+		stdoutFifoPath = filepath.Join(dir, "stdout.fifo")
+		stderrFifoPath = filepath.Join(dir, "stderr.fifo")
+	}
+
+	cfg := &LogConfig{
+		LogDir:        dir,
+		StdoutLogFile: "stdout",
+		StdoutFifo:    stdoutFifoPath,
+		StderrLogFile: "stderr",
+		StderrFifo:    stderrFifoPath,
+		MaxFiles:      2,
+		MaxFileSizeMB: 1,
+	}
+
+	lm := NewLogMon(testlog.HCLogger(t))
+	impl, ok := lm.(*logmonImpl)
+	require.True(ok)
+	require.NoError(lm.Start(cfg))
+
+	stdout, err := fifo.OpenWriter(stdoutFifoPath)
+	require.NoError(err)
+	stderr, err := fifo.OpenWriter(stderrFifoPath)
+	require.NoError(err)
+
+	// Write a string and assert it was written to the file
+	_, err = stdout.Write([]byte("test\n"))
+	require.NoError(err)
+
+	testutil.WaitForResult(func() (bool, error) {
+		raw, err := ioutil.ReadFile(filepath.Join(dir, "stdout.0"))
+		if err != nil {
+			return false, err
+		}
+		return "test\n" == string(raw), fmt.Errorf("unexpected stdout %q", string(raw))
+	}, func(err error) {
+		require.NoError(err)
+	})
+	require.True(impl.tl.IsRunning())
+
+	// Close stdout and assert that logmon no longer writes to the fileA
+	require.NoError(stdout.Close())
+	require.NoError(stderr.Close())
+
+	// Close the task logger
+	impl.tl.Close()
+
+	// Ensure that the task logger is no longer running
+	testutil.WaitForResult(func() (bool, error) {
+		return !impl.tl.IsRunning(), fmt.Errorf("logmon is still running")
+	}, func(err error) {
+		require.NoError(err)
+	})
+
+}
+
 // panicWriter panics on use
 type panicWriter struct{}