Report pull progress to an optionally provided io.Writer

dockerclient.go

@@ -14,6 +14,9 @@ import (
 	"strings"
 	"sync/atomic"
 	"time"
+
+	"github.com/docker/docker/pkg/jsonmessage"
+	"github.com/docker/docker/pkg/term"
 )
 
 const (
@@ -525,21 +528,22 @@ func (client *DockerClient) Version() (*Version, error) {
 	return version, nil
 }
 
-func (client *DockerClient) PullImage(name string, auth *AuthConfig) error {
+func (client *DockerClient) PullImage(name string, auth *AuthConfig, out ...io.Writer) (err error) {
 	v := url.Values{}
 	v.Set("fromImage", name)
 	uri := fmt.Sprintf("/%s/images/create?%s", APIVersion, v.Encode())
-	req, err := http.NewRequest("POST", client.URL.String()+uri, nil)
+	req, _ := http.NewRequest("POST", client.URL.String()+uri, nil)
 	if auth != nil {
 		encoded_auth, err := auth.encode()
 		if err != nil {
 			return err
 		}
 		req.Header.Add("X-Registry-Auth", encoded_auth)
 	}
-	resp, err := client.HTTPClient.Do(req)
+	var resp *http.Response
+	resp, err = client.HTTPClient.Do(req)
 	if err != nil {
-		return err
+		return
 	}
 
 	defer resp.Body.Close()
@@ -554,16 +558,39 @@ func (client *DockerClient) PullImage(name string, auth *AuthConfig) error {
 		return fmt.Errorf("%s", string(data))
 	}
 
+	errorReader := io.Reader(resp.Body)
+	var cliOut io.Writer
+	if len(out) > 0 {
+		cliOut = out[0]
+	}
+	if cliOut != nil {
+		pipeReader, pipeWriter := io.Pipe()
+		streamErrChan := make(chan error)
+		defer func() {
+			pipeWriter.Close()
+			if err == nil {
+				err = <-streamErrChan
+			}
+		}()
+		errorReader = io.TeeReader(resp.Body, pipeWriter)
+		go func() {
+			fd, isTerminalIn := term.GetFdInfo(cliOut)
+			streamErrChan <- jsonmessage.DisplayJSONMessagesStream(pipeReader, cliOut, fd, isTerminalIn)
+		}()
+	}
 	var finalObj map[string]interface{}
-	for decoder := json.NewDecoder(resp.Body); err == nil; err = decoder.Decode(&finalObj) {
+	for decoder := json.NewDecoder(errorReader); err == nil; err = decoder.Decode(&finalObj) {
 	}
 	if err != io.EOF {
-		return err
+		return
+	} else {
+		err = nil
 	}
-	if err, ok := finalObj["error"]; ok {
-		return fmt.Errorf("%v", err)
+	if errObj, ok := finalObj["error"]; ok {
+		err = fmt.Errorf("%v", errObj)
+		return
 	}
-	return nil
+	return
 }
 
 func (client *DockerClient) InspectImage(id string) (*ImageInfo, error) {

dockerclient_test.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"os"
 	"reflect"
 	"strings"
 	"testing"
@@ -31,6 +32,16 @@ func testDockerClient(t *testing.T) *DockerClient {
 	return client
 }
 
+func ExampleDockerClient_PullImage() {
+	docker, err := NewDockerClient("unix:///var/run/docker.sock", nil)
+	if err != nil {
+		panic(err)
+	}
+	if err := docker.PullImage("busybox", nil, os.Stdout); err != nil {
+		panic(err)
+	}
+}
+
 func TestInfo(t *testing.T) {
 	client := testDockerClient(t)
 	info, err := client.Info()
@@ -70,14 +81,14 @@ func TestWait(t *testing.T) {
 
 func TestPullImage(t *testing.T) {
 	client := testDockerClient(t)
-	err := client.PullImage("busybox", nil)
+	err := client.PullImage("busybox", nil) // old clients do not break on the API change
 	if err != nil {
-		t.Fatal("unable to pull busybox")
+		t.Fatal("unable to pull busybox: %v", err)
 	}
 
-	err = client.PullImage("haproxy", nil)
+	err = client.PullImage("haproxy", nil, os.Stderr) // io.Writer is optional
 	if err != nil {
-		t.Fatal("unable to pull haproxy")
+		t.Fatal("unable to pull haproxy: %v", err)
 	}
 
 	err = client.PullImage("wrongimg", nil)

interface.go

@@ -35,7 +35,7 @@ type Client interface {
 	StopAllMonitorStats()
 	TagImage(nameOrID string, repo string, tag string, force bool) error
 	Version() (*Version, error)
-	PullImage(name string, auth *AuthConfig) error
+	PullImage(name string, auth *AuthConfig, out ...io.Writer) error
 	LoadImage(reader io.Reader) error
 	RemoveContainer(id string, force, volumes bool) error
 	ListImages(all bool) ([]*Image, error)

mockclient/mock.go

@@ -106,8 +106,8 @@ func (client *MockClient) Version() (*dockerclient.Version, error) {
 	return args.Get(0).(*dockerclient.Version), args.Error(1)
 }
 
-func (client *MockClient) PullImage(name string, auth *dockerclient.AuthConfig) error {
-	args := client.Mock.Called(name, auth)
+func (client *MockClient) PullImage(name string, auth *dockerclient.AuthConfig, out ...io.Writer) error {
+	args := client.Mock.Called(name, auth, out...)
 	return args.Error(0)
 }
 

nopclient/nop.go

@@ -94,7 +94,7 @@ func (client *NopClient) Version() (*dockerclient.Version, error) {
 	return nil, ErrNoEngine
 }
 
-func (client *NopClient) PullImage(name string, auth *dockerclient.AuthConfig) error {
+func (client *NopClient) PullImage(name string, auth *dockerclient.AuthConfig, out ...io.Writer) error {
 	return ErrNoEngine
 }