builder/docker: can login to pull

CHANGELOG.md

@@ -15,6 +15,7 @@ FEATURES:
       Packer will look in the PWD and the directory with `packer` for
       binaries named `packer-TYPE-NAME`.
   * builder/docker: Images can now be committed instead of exported. [GH-1198]
+  * builder/docker: Can now specify login credentials to pull images.
   * builder/virtualbox-ovf: New `import_flags` setting can be used to add
       new command line flags to `VBoxManage import` to allow things such
       as EULAs to be accepted. [GH-1383]

builder/docker/config.go

@@ -15,6 +15,12 @@ type Config struct {
 	Pull       bool
 	RunCommand []string `mapstructure:"run_command"`
 
+	Login         bool
+	LoginEmail    string `mapstructure:"login_email"`
+	LoginUsername string `mapstructure:"login_username"`
+	LoginPassword string `mapstructure:"login_password"`
+	LoginServer   string `mapstructure:"login_server"`
+
 	tpl *packer.ConfigTemplate
 }
 
@@ -59,8 +65,12 @@ func NewConfig(raws ...interface{}) (*Config, []string, error) {
 	errs := common.CheckUnusedConfig(md)
 
 	templates := map[string]*string{
-		"export_path": &c.ExportPath,
+		"export_path":    &c.ExportPath,
-		"image":       &c.Image,
+		"image":          &c.Image,
+		"login_email":    &c.LoginEmail,
+		"login_username": &c.LoginUsername,
+		"login_password": &c.LoginPassword,
+		"login_server":   &c.LoginServer,
 	}
 
 	for n, ptr := range templates {

builder/docker/step_pull.go

@@ -20,6 +20,29 @@ func (s *StepPull) Run(state multistep.StateBag) multistep.StepAction {
 	}
 
 	ui.Say(fmt.Sprintf("Pulling Docker image: %s", config.Image))
+
+	if config.Login {
+		ui.Message("Logging in...")
+		err := driver.Login(
+			config.LoginServer,
+			config.LoginEmail,
+			config.LoginUsername,
+			config.LoginPassword)
+		if err != nil {
+			err := fmt.Errorf("Error logging in: %s", err)
+			state.Put("error", err)
+			ui.Error(err.Error())
+			return multistep.ActionHalt
+		}
+
+		defer func() {
+			ui.Message("Logging out...")
+			if err := driver.Logout(config.LoginServer); err != nil {
+				ui.Error(fmt.Sprintf("Error logging out: %s", err))
+			}
+		}()
+	}
+
 	if err := driver.Pull(config.Image); err != nil {
 		err := fmt.Errorf("Error pulling Docker image: %s", err)
 		state.Put("error", err)

builder/docker/step_pull_test.go

@@ -51,6 +51,35 @@ func TestStepPull_error(t *testing.T) {
 	}
 }
 
+func TestStepPull_login(t *testing.T) {
+	state := testState(t)
+	step := new(StepPull)
+	defer step.Cleanup(state)
+
+	config := state.Get("config").(*Config)
+	driver := state.Get("driver").(*MockDriver)
+
+	config.Login = true
+
+	// run the step
+	if action := step.Run(state); action != multistep.ActionContinue {
+		t.Fatalf("bad action: %#v", action)
+	}
+
+	// verify we pulled
+	if !driver.PullCalled {
+		t.Fatal("should've pulled")
+	}
+
+	// verify we logged in
+	if !driver.LoginCalled {
+		t.Fatal("should've logged in")
+	}
+	if !driver.LogoutCalled {
+		t.Fatal("should've logged out")
+	}
+}
+
 func TestStepPull_noPull(t *testing.T) {
 	state := testState(t)
 	step := new(StepPull)

website/source/docs/builders/docker.html.markdown

@@ -74,6 +74,18 @@ described.
 
 ### Optional:
 
+* `login` (boolean) - Defaults to false. If true, the builder will
+    login in order to pull the image. The builder only logs in for the
+    duration of the pull. It always logs out afterwards.
+
+* `login_email` (string) - The email to use to authenticate to login.
+
+* `login_username` (string) - The username to use to authenticate to login.
+
+* `login_password` (string) - The password to use to authenticate to login.
+
+* `login_server` (string) - The server address to login to.
+
 * `pull` (boolean) - If true, the configured image will be pulled using
   `docker pull` prior to use. Otherwise, it is assumed the image already
   exists and can be used. This defaults to true if not set.