Configure container streams (#674)

Add output and error container streams configuration on Docker Driver, different from the Operation.Out, which is there to configure the driver logs.

Signed-off-by: Silvin Lubecki <silvin.lubecki@docker.com>

pkg/driver/docker_driver.go

@@ -28,6 +28,8 @@ type DockerDriver struct {
 	Simulate                   bool
 	dockerCli                  command.Cli
 	dockerConfigurationOptions []DockerConfigurationOption
+	containerOut               io.Writer
+	containerErr               io.Writer
 }
 
 // Run executes the Docker driver
@@ -64,6 +66,16 @@ func (d *DockerDriver) SetDockerCli(dockerCli command.Cli) {
 	d.dockerCli = dockerCli
 }
 
+// SetContainerOut sets the container output stream
+func (d *DockerDriver) SetContainerOut(w io.Writer) {
+	d.containerOut = w
+}
+
+// SetContainerErr sets the container error stream
+func (d *DockerDriver) SetContainerErr(w io.Writer) {
+	d.containerErr = w
+}
+
 func pullImage(ctx context.Context, cli command.Cli, image string) error {
 	ref, err := reference.ParseNormalizedNamed(image)
 	if err != nil {
@@ -185,10 +197,20 @@ func (d *DockerDriver) exec(op *Operation) error {
 	if err != nil {
 		return fmt.Errorf("unable to retrieve logs: %v", err)
 	}
+	var (
+		stdout io.Writer = os.Stdout
+		stderr io.Writer = os.Stderr
+	)
+	if d.containerOut != nil {
+		stdout = d.containerOut
+	}
+	if d.containerErr != nil {
+		stderr = d.containerErr
+	}
 	go func() {
 		defer attach.Close()
 		for {
-			_, err := stdcopy.StdCopy(os.Stdout, os.Stderr, attach.Reader)
+			_, err := stdcopy.StdCopy(stdout, stderr, attach.Reader)
 			if err != nil {
 				break
 			}

pkg/driver/driver.go

@@ -80,7 +80,7 @@ type DebugDriver struct {
 	config map[string]string
 }
 
-// Run executes the operation on the Debug  driver
+// Run executes the operation on the Debug driver
 func (d *DebugDriver) Run(op *Operation) error {
 	data, err := json.MarshalIndent(op, "", "  ")
 	if err != nil {