sample.go

package main

import (
	"golang.org/x/net/context"
	"github.com/docker/docker/api/types"
	"github.com/docker/docker/api/types/container"
	"github.com/docker/docker/api/types/network"
	"github.com/docker/docker/cli/command"
	"github.com/docker/docker/client"
	"fmt"
	"os"
)

var (
	err error
	appName string
)

// Keep constants with sensitive information in one place
const (
	DefaultServer = "registry.gitlab.com"
	Username = "xxxxx"
	Password = "xxxxx"
)

// App struct holds information about the app that should be launched
// with auth and docker client info
type App struct {
	Name              string
	Client            *client.Client
	AuthConfig        types.AuthConfig
	AuthConfigEncoded string
	Config            container.ContainerCreateCreatedBody
}

func registryAuthentication(image string) types.RequestPrivilegeFunc {
	return func() (string, error) {
		authConfig := types.AuthConfig{
			Username: Username,
			Password: Password,
			ServerAddress: DefaultServer,
		}
		base64config, err := command.EncodeAuthToBase64(authConfig)
		if err != nil {
			return "", err
		}
		return base64config, nil
	}
}

// Initialize application from environment variable
func (app *App) Initialize() error {
	app.Client, err = client.NewEnvClient()
	return err
}

// Prepare auth registry for usage
func (app *App) PrepareRegistry() error {
	app.AuthConfig = types.AuthConfig{
		Username:      Username,
		Password:      Password,
		ServerAddress: DefaultServer,
	}

	resp, err := app.Client.RegistryLogin(context.Background(), app.AuthConfig)
	if err != nil {
		panic(err)
	}

	fmt.Println("Status:\t", resp.Status)
	if resp.IdentityToken != "" {
		app.AuthConfig.IdentityToken = resp.IdentityToken
	}

	app.AuthConfigEncoded, err = command.EncodeAuthToBase64(app.AuthConfig)
	return err
}

func (app *App) ImagePull() error {

	opts := types.ImagePullOptions{
		RegistryAuth: app.AuthConfigEncoded,
		PrivilegeFunc: registryAuthentication(app.Name),
	}
	_, err := app.Client.ImagePull(context.Background(), DefaultServer + "magnus/atom", opts)
	if err != nil {
		return err
	}
	return nil
}

func (app *App) ImageIsLoaded() bool {
	result, err := app.Client.ImageSearch(context.Background(), app.Name, types.ImageSearchOptions{Limit: 1})

	if err != nil {
		panic(err)
	}

	if len(result) != 0 {
		return true
	}
	return false
}

// Create config for container
func (app *App) ContainerCreate() error {
	// Wait for image to be pulled
	for !app.ImageIsLoaded() {
		app.Config, err = app.Client.ContainerCreate(
			context.Background(),
			&container.Config{Image: app.Name},
			&container.HostConfig{},
			&network.NetworkingConfig{},
			"")
		return err
	}
	return nil
}

// Launch container with the `App.Name`
func (app *App) ContainerStart() error {
	return app.Client.ContainerStart(context.Background(), app.Config.ID, types.ContainerStartOptions{})
}

// Launch app
func (app *App) Start() {

	err = app.Initialize()
	if err != nil {
		panic(err)
	}

	err = app.PrepareRegistry()
	if err != nil {
		panic(err)
	}

	err = app.ImagePull()
	if err != nil {
		panic(err)
	}

	err = app.ContainerCreate()
	if err != nil {
		panic(err)
	}

	err = app.ContainerStart()
	if err != nil {
		panic(err)
	}

}

func main() {
	if len(os.Args) > 1 {
		appName = os.Args[1]
		app := App{Name: "magnus/" + appName}
		app.Start()
		fmt.Sprintln("Launched", appName)
	} else {
		fmt.Println("Please, provide app name")
	}
}