Wait for copier finishing it's work before closing logger

Signed-off-by: Alexander Morozov <lk4d4@docker.com>

daemon/container.go

@@ -105,6 +105,7 @@ type Container struct {
 	execCommands *execStore
 	// logDriver for closing
 	logDriver          logger.Logger
+	logCopier          *logger.Copier
 	AppliedVolumesFrom map[string]struct{}
 }
 
@@ -1383,11 +1384,12 @@ func (container *Container) startLogging() error {
 		return fmt.Errorf("Unknown logging driver: %s", cfg.Type)
 	}
 
-	if copier, err := logger.NewCopier(container.ID, map[string]io.Reader{"stdout": container.StdoutPipe(), "stderr": container.StderrPipe()}, l); err != nil {
+	copier, err := logger.NewCopier(container.ID, map[string]io.Reader{"stdout": container.StdoutPipe(), "stderr": container.StderrPipe()}, l)
+	if err != nil {
 		return err
-	} else {
-		copier.Run()
 	}
+	container.logCopier = copier
+	copier.Run()
 	container.logDriver = l
 
 	return nil

daemon/logger/copier.go

@@ -3,6 +3,7 @@ package logger
 import (
 	"bufio"
 	"io"
+	"sync"
 	"time"
 
 	"github.com/Sirupsen/logrus"
@@ -15,8 +16,9 @@ type Copier struct {
 	// cid is container id for which we copying logs
 	cid string
 	// srcs is map of name -> reader pairs, for example "stdout", "stderr"
-	srcs map[string]io.Reader
+	srcs     map[string]io.Reader
-	dst  Logger
+	dst      Logger
+	copyJobs sync.WaitGroup
 }
 
 // NewCopier creates new Copier
@@ -31,11 +33,13 @@ func NewCopier(cid string, srcs map[string]io.Reader, dst Logger) (*Copier, erro
 // Run starts logs copying
 func (c *Copier) Run() {
 	for src, w := range c.srcs {
+		c.copyJobs.Add(1)
 		go c.copySrc(src, w)
 	}
 }
 
 func (c *Copier) copySrc(name string, src io.Reader) {
+	defer c.copyJobs.Done()
 	scanner := bufio.NewScanner(src)
 	for scanner.Scan() {
 		if err := c.dst.Log(&Message{ContainerID: c.cid, Line: scanner.Bytes(), Source: name, Timestamp: time.Now().UTC()}); err != nil {
@@ -46,3 +50,8 @@ func (c *Copier) copySrc(name string, src io.Reader) {
 		logrus.Errorf("Error scanning log stream: %s", err)
 	}
 }
+
+// Wait waits until all copying is done
+func (c *Copier) Wait() {
+	c.copyJobs.Wait()
+}

daemon/logger/copier_test.go

@@ -70,7 +70,16 @@ func TestCopier(t *testing.T) {
 		t.Fatal(err)
 	}
 	c.Run()
-	time.Sleep(100 * time.Millisecond)
+	wait := make(chan struct{})
+	go func() {
+		c.Wait()
+		close(wait)
+	}()
+	select {
+	case <-time.After(1 * time.Second):
+		t.Fatal("Copier failed to do its work in 1 second")
+	case <-wait:
+	}
 	dec := json.NewDecoder(&jsonBuf)
 	for {
 		var msg Message

daemon/monitor.go

@@ -303,7 +303,20 @@ func (m *containerMonitor) resetContainer(lock bool) {
 	}
 
 	if container.logDriver != nil {
+		if container.logCopier != nil {
+			exit := make(chan struct{})
+			go func() {
+				container.logCopier.Wait()
+				close(exit)
+			}()
+			select {
+			case <-time.After(1 * time.Second):
+				log.Warnf("Logger didn't exit in time: logs may be truncated")
+			case <-exit:
+			}
+		}
 		container.logDriver.Close()
+		container.logCopier = nil
 		container.logDriver = nil
 	}