// 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(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{
        All:            true,
        RegistryAuth: app.AuthConfigEncoded,
        PrivilegeFunc: registryAuthentication(app.Name),
    }
    responseBody, err := app.Client.ImagePull(context.Background(), app.Name, opts)
    defer responseBody.Close()
    if err != nil {
        return err
    }
    return nil
}

Login Succeeded
panic: Error response from daemon: Get https://registry-1.docker.io/v2/shalakhin/blender/tags/list: unauthorized: incorrect username or password