@@ -245,6 +245,10 @@ func (l *logStream) Name() string {

 	return name

 }

+func (l *logStream) BufSize() int {

+	return maximumBytesPerEvent

+}

+

 // Log submits messages for logging by an instance of the awslogs logging driver

 func (l *logStream) Log(msg *logger.Message) error {

 	l.lock.RLock()

@@ -1049,6 +1049,11 @@ func TestCreateTagSuccess(t *testing.T) {

 	}

 }

+func TestIsSizedLogger(t *testing.T) {

+	awslogs := &logStream{}

+	assert.Implements(t, (*logger.SizedLogger)(nil), awslogs, "awslogs should implement SizedLogger")

+}

+

 func BenchmarkUnwrapEvents(b *testing.B) {

 	events := make([]wrappedEvent, maximumLogEventsPerPut)

 	for i := 0; i < maximumLogEventsPerPut; i++ {

@@ -10,8 +10,13 @@ import (

 )

 const (

-	bufSize  = 16 * 1024

+	// readSize is the maximum bytes read during a single read

+	// operation.

 	readSize = 2 * 1024

+

+	// defaultBufSize provides a reasonable default for loggers that do

+	// not have an external limit to impose on log line size.

+	defaultBufSize = 16 * 1024

 )

 // Copier can copy logs from specified sources to Logger and attach Timestamp.

@@ -44,7 +49,13 @@ func (c *Copier) Run() {

 func (c *Copier) copySrc(name string, src io.Reader) {

 	defer c.copyJobs.Done()

+

+	bufSize := defaultBufSize

+	if sizedLogger, ok := c.dst.(SizedLogger); ok {

+		bufSize = sizedLogger.BufSize()

+	}

 	buf := make([]byte, bufSize)

+

 	n := 0

 	eof := false

@@ -31,6 +31,25 @@ func (l *TestLoggerJSON) Close() error { return nil }

 func (l *TestLoggerJSON) Name() string { return "json" }

+type TestSizedLoggerJSON struct {

+	*json.Encoder

+	mu sync.Mutex

+}

+

+func (l *TestSizedLoggerJSON) Log(m *Message) error {

+	l.mu.Lock()

+	defer l.mu.Unlock()

+	return l.Encode(m)

+}

+

+func (*TestSizedLoggerJSON) Close() error { return nil }

+

+func (*TestSizedLoggerJSON) Name() string { return "sized-json" }

+

+func (*TestSizedLoggerJSON) BufSize() int {

+	return 32 * 1024

+}

+

 func TestCopier(t *testing.T) {

 	stdoutLine := "Line that thinks that it is log line from docker stdout"

 	stderrLine := "Line that thinks that it is log line from docker stderr"

@@ -104,10 +123,9 @@ func TestCopier(t *testing.T) {

 // TestCopierLongLines tests long lines without line breaks

 func TestCopierLongLines(t *testing.T) {

-	// Long lines (should be split at "bufSize")

-	const bufSize = 16 * 1024

-	stdoutLongLine := strings.Repeat("a", bufSize)

-	stderrLongLine := strings.Repeat("b", bufSize)

+	// Long lines (should be split at "defaultBufSize")

+	stdoutLongLine := strings.Repeat("a", defaultBufSize)

+	stderrLongLine := strings.Repeat("b", defaultBufSize)

 	stdoutTrailingLine := "stdout trailing line"

 	stderrTrailingLine := "stderr trailing line"

@@ -205,6 +223,41 @@ func TestCopierSlow(t *testing.T) {

 	}

 }

+func TestCopierWithSized(t *testing.T) {

+	var jsonBuf bytes.Buffer

+	expectedMsgs := 2

+	sizedLogger := &TestSizedLoggerJSON{Encoder: json.NewEncoder(&jsonBuf)}

+	logbuf := bytes.NewBufferString(strings.Repeat(".", sizedLogger.BufSize()*expectedMsgs))

+	c := NewCopier(map[string]io.Reader{"stdout": logbuf}, sizedLogger)

+

+	c.Run()

+	// Wait for Copier to finish writing to the buffered logger.

+	c.Wait()

+	c.Close()

+

+	recvdMsgs := 0

+	dec := json.NewDecoder(&jsonBuf)

+	for {

+		var msg Message

+		if err := dec.Decode(&msg); err != nil {

+			if err == io.EOF {

+				break

+			}

+			t.Fatal(err)

+		}

+		if msg.Source != "stdout" {

+			t.Fatalf("Wrong Source: %q, should be %q", msg.Source, "stdout")

+		}

+		if len(msg.Line) != sizedLogger.BufSize() {

+			t.Fatalf("Line was not of expected max length %d, was %d", sizedLogger.BufSize(), len(msg.Line))

+		}

+		recvdMsgs++

+	}

+	if recvdMsgs != expectedMsgs {

+		t.Fatalf("expected to receive %d messages, actually received %d", expectedMsgs, recvdMsgs)

+	}

+}

+

 type BenchmarkLoggerDummy struct {

 }

@@ -81,6 +81,13 @@ type Logger interface {

 	Close() error

 }

+// SizedLogger is the interface for logging drivers that can control

+// the size of buffer used for their messages.

+type SizedLogger interface {

+	Logger

+	BufSize() int

+}

+

 // ReadConfig is the configuration passed into ReadLogs.

 type ReadConfig struct {

 	Since  time.Time