Fix docker flaky test (#1494)

pkg/acquisition/modules/docker/docker.go

@@ -462,10 +462,10 @@ func ReadTailScanner(scanner *bufio.Scanner, out chan string, t *tomb.Tomb) erro
 	for scanner.Scan() {
 		out <- scanner.Text()
 	}
-	return nil
+	return scanner.Err()
 }
 
-func (d *DockerSource) TailDocker(container *ContainerConfig, outChan chan types.Event) error {
+func (d *DockerSource) TailDocker(container *ContainerConfig, outChan chan types.Event, deleteChan chan *ContainerConfig) error {
 	container.logger.Infof("start tail for container %s", container.Name)
 	dockerReader, err := d.Client.ContainerLogs(context.Background(), container.ID, *d.containerLogsOptions)
 	if err != nil {
@@ -511,7 +511,7 @@ func (d *DockerSource) TailDocker(container *ContainerConfig, outChan chan types
 			//This case is to handle temporarily losing the connection to the docker socket
 			//The only known case currently is when using docker-socket-proxy (and maybe a docker daemon restart)
 			d.logger.Debugf("readerTomb dying for container %s, removing it from runningContainerState", container.Name)
-			delete(d.runningContainerState, container.ID)
+			deleteChan <- container
 			//Also reset the Since to avoid re-reading logs
 			d.Config.Since = time.Now().UTC().Format(time.RFC3339)
 			d.containerLogsOptions.Since = d.Config.Since
@@ -529,7 +529,7 @@ func (d *DockerSource) DockerManager(in chan *ContainerConfig, deleteChan chan *
 				newContainer.t = &tomb.Tomb{}
 				newContainer.logger = d.logger.WithFields(log.Fields{"container_name": newContainer.Name})
 				newContainer.t.Go(func() error {
-					return d.TailDocker(newContainer, outChan)
+					return d.TailDocker(newContainer, outChan, deleteChan)
 				})
 				d.runningContainerState[newContainer.ID] = newContainer
 			}

pkg/acquisition/modules/docker/docker_test.go

@@ -2,6 +2,7 @@ package dockeracquisition
 
 import (
 	"context"
+	"encoding/binary"
 	"fmt"
 	"io"
 	"os"
@@ -22,6 +23,8 @@ import (
 
 const testContainerName = "docker_test"
 
+var readLogs = false
+
 func TestConfigure(t *testing.T) {
 	log.Infof("Test 'TestConfigure'")
 
@@ -159,6 +162,7 @@ container_name_regexp:
 			})
 		}
 
+		readLogs = false
 		dockerTomb := tomb.Tomb{}
 		out := make(chan types.Event)
 		dockerSource := DockerSource{}
@@ -188,13 +192,11 @@ container_name_regexp:
 				}
 			}
 		})
-		time.Sleep(10 * time.Second)
 		cstest.AssertErrorContains(t, err, ts.expectedErr)
 
 		if err := readerTomb.Wait(); err != nil {
 			t.Fatal(err)
 		}
-		//time.Sleep(4 * time.Second)
 		if ts.expectedLines != 0 {
 			assert.Equal(t, ts.expectedLines, actualLines)
 		}
@@ -207,6 +209,9 @@ container_name_regexp:
 }
 
 func (cli *mockDockerCli) ContainerList(ctx context.Context, options dockerTypes.ContainerListOptions) ([]dockerTypes.Container, error) {
+	if readLogs == true {
+		return []dockerTypes.Container{}, nil
+	}
 	containers := make([]dockerTypes.Container, 0)
 	container := &dockerTypes.Container{
 		ID:    "12456",
@@ -218,11 +223,17 @@ func (cli *mockDockerCli) ContainerList(ctx context.Context, options dockerTypes
 }
 
 func (cli *mockDockerCli) ContainerLogs(ctx context.Context, container string, options dockerTypes.ContainerLogsOptions) (io.ReadCloser, error) {
-	startLineByte := "\x01\x00\x00\x00\x00\x00\x00\x1f"
+	if readLogs == true {
-	data := []string{"docker", "test", "1234"}
+		return io.NopCloser(strings.NewReader("")), nil
+	}
+	readLogs = true
+	data := []string{"docker\n", "test\n", "1234\n"}
 	ret := ""
 	for _, line := range data {
-		ret += fmt.Sprintf("%s%s\n", startLineByte, line)
+		startLineByte := make([]byte, 8)
+		binary.LittleEndian.PutUint32(startLineByte, 1) //stdout stream
+		binary.BigEndian.PutUint32(startLineByte[4:], uint32(len(line)))
+		ret += fmt.Sprintf("%s%s", startLineByte, line)
 	}
 	r := io.NopCloser(strings.NewReader(ret)) // r type is io.ReadCloser
 	return r, nil
@@ -281,6 +292,7 @@ func TestOneShot(t *testing.T) {
 			})
 		}
 
+		readLogs = false
 		dockerClient := &DockerSource{}
 		labels := make(map[string]string)
 		labels["type"] = ts.logType