sap-jenkins-library/pkg/docker/docker.go

package docker

import (
	"fmt"
	"io"
	"net/url"
	"strings"

	pkgutil "github.com/GoogleContainerTools/container-diff/pkg/util"
	"github.com/google/go-containerregistry/pkg/legacy/tarball"
	"github.com/google/go-containerregistry/pkg/name"
)

// Client defines an docker client object
type Client struct {
	imageName     string
	registryURL   string
	localPath     string
	includeLayers bool
}

// ClientOptions defines the options to be set on the client
type ClientOptions struct {
	ImageName     string
	RegistryURL   string
	LocalPath     string
	IncludeLayers bool
}

//Download interface for download an image to a local path
type Download interface {
	GetImageSource() (string, error)
	DownloadImageToPath(imageSource, filePath string) (pkgutil.Image, error)
	TarImage(writer io.Writer, image pkgutil.Image) error
}

// SetOptions sets options used for the docker client
func (c *Client) SetOptions(options ClientOptions) {
	c.imageName = options.ImageName
	c.registryURL = options.RegistryURL
	c.includeLayers = options.IncludeLayers
	c.localPath = options.LocalPath
}

const (
	daemonPrefix = "daemon://"
	remotePrefix = "remote://"
)

//GetImageSource get the image source from client attributes (localPath, imageName, registryURL)
func (c *Client) GetImageSource() (string, error) {

	imageSource := c.imageName

	if len(c.registryURL) > 0 && len(c.localPath) <= 0 {
		registry := c.registryURL

		url, _ := url.Parse(c.registryURL)
		//remove protocoll from registryURL to get registry
		if len(url.Scheme) > 0 {
			registry = strings.Replace(c.registryURL, fmt.Sprintf("%v://", url.Scheme), "", 1)
		}

		if strings.HasSuffix(registry, "/") {
			imageSource = fmt.Sprintf("%v%v%v", remotePrefix, registry, c.imageName)
		} else {
			imageSource = fmt.Sprintf("%v%v/%v", remotePrefix, registry, c.imageName)
		}
	} else if len(c.localPath) > 0 {
		imageSource = c.localPath
		if !pkgutil.IsTar(c.localPath) {
			imageSource = fmt.Sprintf("%v%v", daemonPrefix, c.localPath)
		}
	}

	if len(imageSource) <= 0 {
		return imageSource, fmt.Errorf("There is no image source for the parameters: (Name: %v, Registry: %v, local Path: %v)", c.imageName, c.registryURL, c.localPath)
	}

	return imageSource, nil
}

//DownloadImageToPath download the image to the specified path
func (c *Client) DownloadImageToPath(imageSource, filePath string) (pkgutil.Image, error) {

	return pkgutil.GetImage(imageSource, c.includeLayers, filePath)
}

//TarImage write a tar from the given image
func (c *Client) TarImage(writer io.Writer, image pkgutil.Image) error {

	reference, err := name.ParseReference(image.Digest.String(), name.WeakValidation)
	if err != nil {
		return err
	}
	err = tarball.Write(reference, image.Image, writer)
	if err != nil {
		return err
	}
	return nil
}