Golang Config.Source方法代码示例

// New returns a new instance of OnBuild builder
func New(config *api.Config, overrides build.Overrides) (*OnBuild, error) {
	dockerHandler, err := docker.New(config.DockerConfig, config.PullAuthentication)
	if err != nil {
		return nil, err
	}
	b := &OnBuild{
		docker: dockerHandler,
		git:    git.New(),
		fs:     util.NewFileSystem(),
		tar:    tar.New(),
	}
	// Use STI Prepare() and download the 'run' script optionally.
	s, err := sti.New(config, overrides)
	s.SetScripts([]string{}, []string{api.Assemble, api.Run})

	downloader := overrides.Downloader
	if downloader == nil {
		d, sourceURL, err := scm.DownloaderForSource(config.Source)
		if err != nil {
			return nil, err
		}
		downloader = d
		config.Source = sourceURL
	}

	b.source = onBuildSourceHandler{
		Downloader: downloader,
		Preparer:   s,
		Ignorer:    &ignore.DockerIgnorer{},
	}

	b.garbage = &build.DefaultCleaner{b.fs, b.docker}
	return b, nil
}

// Restore loads the arguments from disk and prefills the Request
func Restore(config *api.Config, cmd *cobra.Command) {
	data, err := ioutil.ReadFile(DefaultConfigPath)
	if err != nil {
		data, err = ioutil.ReadFile(".stifile")
		if err != nil {
			glog.V(1).Infof("Unable to restore %s: %v", DefaultConfigPath, err)
			return
		}
		glog.Infof("DEPRECATED: Use %s instead of .stifile", DefaultConfigPath)
	}
	c := Config{}
	if err := json.Unmarshal(data, &c); err != nil {
		glog.V(1).Infof("Unable to parse %s: %v", DefaultConfigPath, err)
		return
	}
	config.BuilderImage = c.BuilderImage
	config.Source = c.Source
	config.Tag = c.Tag
	for name, value := range c.Flags {
		// Do not change flags that user sets. Allow overriding of stored flags.
		if cmd.Flag(name).Changed {
			continue
		}
		cmd.Flags().Set(name, value)
	}
}

// New returns the instance of STI builder strategy for the given config.
// If the layeredBuilder parameter is specified, then the builder provided will
// be used for the case that the base Docker image does not have 'tar' or 'bash'
// installed.
func New(req *api.Config, overrides build.Overrides) (*STI, error) {
	docker, err := dockerpkg.New(req.DockerConfig, req.PullAuthentication)
	if err != nil {
		return nil, err
	}
	var incrementalDocker dockerpkg.Docker
	if req.Incremental {
		incrementalDocker, err = dockerpkg.New(req.DockerConfig, req.IncrementalAuthentication)
		if err != nil {
			return nil, err
		}
	}

	inst := scripts.NewInstaller(req.BuilderImage, req.ScriptsURL, docker, req.PullAuthentication)

	b := &STI{
		installer:         inst,
		config:            req,
		docker:            docker,
		incrementalDocker: incrementalDocker,
		git:               git.New(),
		fs:                util.NewFileSystem(),
		tar:               tar.New(),
		callbackInvoker:   util.NewCallbackInvoker(),
		requiredScripts:   []string{api.Assemble, api.Run},
		optionalScripts:   []string{api.SaveArtifacts},
		externalScripts:   map[string]bool{},
		installedScripts:  map[string]bool{},
		scriptsURL:        map[string]string{},
	}

	// The sources are downloaded using the GIT downloader.
	// TODO: Add more SCM in future.
	// TODO: explicit decision made to customize processing for usage specifically vs.
	// leveraging overrides; also, we ultimately want to simplify s2i usage a good bit,
	// which would lead to replacing this quick short circuit (so this change is tactical)
	b.source = overrides.Downloader
	if b.source == nil && !req.Usage {
		downloader, sourceURL, err := scm.DownloaderForSource(req.Source, req.ForceCopy)
		if err != nil {
			return nil, err
		}
		b.source = downloader
		req.Source = sourceURL
	}

	b.garbage = &build.DefaultCleaner{b.fs, b.docker}
	b.layered, err = layered.New(req, b, overrides)

	// Set interfaces
	b.preparer = b
	// later on, if we support say .gitignore func in addition to .dockerignore func, setting
	// ignorer will be based on config setting
	b.ignorer = &ignore.DockerIgnorer{}
	b.artifacts = b
	b.scripts = b
	b.postExecutor = b
	return b, err
}

// New returns the instance of STI builder strategy for the given config.
// If the layeredBuilder parameter is specified, then the builder provided will
// be used for the case that the base Docker image does not have 'tar' or 'bash'
// installed.
func New(req *api.Config, overrides build.Overrides) (*STI, error) {
	docker, err := dockerpkg.New(req.DockerConfig, req.PullAuthentication)
	if err != nil {
		return nil, err
	}
	var incrementalDocker dockerpkg.Docker
	if req.Incremental {
		incrementalDocker, err = dockerpkg.New(req.DockerConfig, req.IncrementalAuthentication)
		if err != nil {
			return nil, err
		}
	}

	inst := scripts.NewInstaller(req.BuilderImage, req.ScriptsURL, docker, req.PullAuthentication)

	b := &STI{
		installer:         inst,
		config:            req,
		docker:            docker,
		incrementalDocker: incrementalDocker,
		git:               git.New(),
		fs:                util.NewFileSystem(),
		tar:               tar.New(),
		callbackInvoker:   util.NewCallbackInvoker(),
		requiredScripts:   []string{api.Assemble, api.Run},
		optionalScripts:   []string{api.SaveArtifacts},
		externalScripts:   map[string]bool{},
		installedScripts:  map[string]bool{},
		scriptsURL:        map[string]string{},
	}

	// The sources are downloaded using the GIT downloader.
	// TODO: Add more SCM in future.
	b.source = overrides.Downloader
	if b.source == nil {
		downloader, sourceURL, err := scm.DownloaderForSource(req.Source)
		if err != nil {
			return nil, err
		}
		b.source = downloader
		req.Source = sourceURL
	}

	b.garbage = &build.DefaultCleaner{b.fs, b.docker}
	b.layered, err = layered.New(req, b, overrides)

	// Set interfaces
	b.preparer = b
	// later on, if we support say .gitignore func in addition to .dockerignore func, setting
	// ignorer will be based on config setting
	b.ignorer = &ignore.DockerIgnorer{}
	b.artifacts = b
	b.scripts = b
	b.postExecutor = b
	return b, err
}

// GenerateConfigFromLabels generates the S2I Config struct from the Docker
// image labels.
func GenerateConfigFromLabels(image string, config *api.Config) error {
	d, err := docker.New(config.DockerConfig, config.PullAuthentication)
	if err != nil {
		return err
	}

	var source *dockerclient.Image
	if config.ForcePull {
		source, err = d.PullImage(image)
	} else {
		source, err = d.CheckAndPullImage(image)
	}

	if err != nil {
		return err
	}

	if builderVersion, ok := source.Config.Labels["io.openshift.builder-version"]; ok {
		config.BuilderImageVersion = builderVersion
		config.BuilderBaseImageVersion = source.Config.Labels["io.openshift.builder-base-version"]
	}

	config.ScriptsURL = source.Config.Labels[api.DefaultNamespace+"scripts-url"]
	if len(config.ScriptsURL) == 0 {
		// FIXME: Backward compatibility
		config.ScriptsURL = source.Config.Labels["io.s2i.scripts-url"]
	}

	config.Description = source.Config.Labels[api.KubernetesNamespace+"description"]
	config.DisplayName = source.Config.Labels[api.KubernetesNamespace+"display-name"]

	if builder, ok := source.Config.Labels[api.DefaultNamespace+"build.image"]; ok {
		config.BuilderImage = builder
	} else {
		return fmt.Errorf("Required label %q not found in image", api.DefaultNamespace+"build.image")
	}

	if repo, ok := source.Config.Labels[api.DefaultNamespace+"build.source-location"]; ok {
		config.Source = repo
	} else {
		return fmt.Errorf("Required label %q not found in image", api.DefaultNamespace+"source-location")
	}

	config.ContextDir = source.Config.Labels[api.DefaultNamespace+"build.source-context-dir"]
	config.Ref = source.Config.Labels[api.DefaultNamespace+"build.commit.ref"]

	return nil
}

// GenerateConfigFromLabels generates the S2I Config struct from the Docker
// image labels.
func GenerateConfigFromLabels(config *api.Config, metadata *docker.PullResult) error {
	if config == nil {
		return errors.New("config must be provided to GenerateConfigFromLabels")
	}
	if metadata == nil {
		return errors.New("image metadata must be provided to GenerateConfigFromLabels")
	}

	labels := metadata.Image.Config.Labels

	if builderVersion, ok := labels["io.openshift.builder-version"]; ok {
		config.BuilderImageVersion = builderVersion
		config.BuilderBaseImageVersion = labels["io.openshift.builder-base-version"]
	}

	config.ScriptsURL = labels[api.DefaultNamespace+"scripts-url"]
	if len(config.ScriptsURL) == 0 {
		// FIXME: Backward compatibility
		config.ScriptsURL = labels["io.s2i.scripts-url"]
	}

	config.Description = labels[api.KubernetesNamespace+"description"]
	config.DisplayName = labels[api.KubernetesNamespace+"display-name"]

	if builder, ok := labels[api.DefaultNamespace+"build.image"]; ok {
		config.BuilderImage = builder
	} else {
		return fmt.Errorf("Required label %q not found in image", api.DefaultNamespace+"build.image")
	}

	if repo, ok := labels[api.DefaultNamespace+"build.source-location"]; ok {
		config.Source = repo
	} else {
		return fmt.Errorf("Required label %q not found in image", api.DefaultNamespace+"source-location")
	}

	config.ContextDir = labels[api.DefaultNamespace+"build.source-context-dir"]
	config.Ref = labels[api.DefaultNamespace+"build.commit.ref"]

	return nil
}

// GenerateConfigFromLabels generates the S2I Config struct from the Docker
// image labels.
func GenerateConfigFromLabels(config *api.Config) error {
	result, err := docker.GetBuilderImage(config)
	if err != nil {
		return err
	}
	labels := result.Image.Config.Labels

	if builderVersion, ok := labels["io.openshift.builder-version"]; ok {
		config.BuilderImageVersion = builderVersion
		config.BuilderBaseImageVersion = labels["io.openshift.builder-base-version"]
	}

	config.ScriptsURL = labels[api.DefaultNamespace+"scripts-url"]
	if len(config.ScriptsURL) == 0 {
		// FIXME: Backward compatibility
		config.ScriptsURL = labels["io.s2i.scripts-url"]
	}

	config.Description = labels[api.KubernetesNamespace+"description"]
	config.DisplayName = labels[api.KubernetesNamespace+"display-name"]

	if builder, ok := labels[api.DefaultNamespace+"build.image"]; ok {
		config.BuilderImage = builder
	} else {
		return fmt.Errorf("Required label %q not found in image", api.DefaultNamespace+"build.image")
	}

	if repo, ok := labels[api.DefaultNamespace+"build.source-location"]; ok {
		config.Source = repo
	} else {
		return fmt.Errorf("Required label %q not found in image", api.DefaultNamespace+"source-location")
	}

	config.ContextDir = labels[api.DefaultNamespace+"build.source-context-dir"]
	config.Ref = labels[api.DefaultNamespace+"build.commit.ref"]

	return nil
}

func newCmdBuild(cfg *api.Config) *cobra.Command {
	useConfig := false
	oldScriptsFlag := ""
	oldDestination := ""

	buildCmd := &cobra.Command{
		Use:   "build <source> <image> [<tag>]",
		Short: "Build a new image",
		Long:  "Build a new Docker image named <tag> (if provided) from a source repository and base image.",
		Example: `
# Build an application Docker image from a Git repository
$ s2i build git://github.com/openshift/ruby-hello-world centos/ruby-22-centos7 hello-world-app

# Build from a local directory
$ s2i build . centos/ruby-22-centos7 hello-world-app
`,
		Run: func(cmd *cobra.Command, args []string) {
			glog.V(1).Infof("Running S2I version %q\n", version.Get())

			// Attempt to restore the build command from the configuration file
			if useConfig {
				config.Restore(cfg, cmd)
			}

			// If user specifies the arguments, then we override the stored ones
			if len(args) >= 2 {
				cfg.Source = args[0]
				cfg.BuilderImage = args[1]
				if len(args) >= 3 {
					cfg.Tag = args[2]
				}
			}

			if cfg.Incremental && len(cfg.RuntimeImage) > 0 {
				fmt.Fprintln(os.Stderr, "ERROR: Incremental build with runtime image isn't supported")
				os.Exit(1)
			}
			if cfg.ForcePull {
				glog.Warning("DEPRECATED: The '--force-pull' option is deprecated. Use '--pull-policy' instead")
			}

			if len(cfg.BuilderPullPolicy) == 0 {
				cfg.BuilderPullPolicy = api.DefaultBuilderPullPolicy
			}
			if len(cfg.PreviousImagePullPolicy) == 0 {
				cfg.PreviousImagePullPolicy = api.DefaultPreviousImagePullPolicy
			}

			if errs := validation.ValidateConfig(cfg); len(errs) > 0 {
				for _, e := range errs {
					fmt.Fprintf(os.Stderr, "ERROR: %s\n", e)
				}
				fmt.Println()
				cmd.Help()
				os.Exit(1)
			}

			// Persists the current command line options and config into .s2ifile
			if useConfig {
				config.Save(cfg, cmd)
			}

			// Attempt to read the .dockercfg and extract the authentication for
			// docker pull
			if r, err := os.Open(cfg.DockerCfgPath); err == nil {
				defer r.Close()
				auths := docker.LoadImageRegistryAuth(r)
				cfg.PullAuthentication = docker.GetImageRegistryAuth(auths, cfg.BuilderImage)
				if cfg.Incremental {
					cfg.IncrementalAuthentication = docker.GetImageRegistryAuth(auths, cfg.Tag)
				}
				if len(cfg.RuntimeImage) > 0 {
					cfg.RuntimeAuthentication = docker.GetImageRegistryAuth(auths, cfg.RuntimeImage)
				}
			}

			if len(cfg.EnvironmentFile) > 0 {
				result, err := util.ReadEnvironmentFile(cfg.EnvironmentFile)
				if err != nil {
					glog.Warningf("Unable to read environment file %q: %v", cfg.EnvironmentFile, err)
				} else {
					for name, value := range result {
						cfg.Environment = append(cfg.Environment, api.EnvironmentSpec{Name: name, Value: value})
					}
				}
			}

			if len(oldScriptsFlag) != 0 {
				glog.Warning("DEPRECATED: Flag --scripts is deprecated, use --scripts-url instead")
				cfg.ScriptsURL = oldScriptsFlag
			}
			if len(oldDestination) != 0 {
				glog.Warning("DEPRECATED: Flag --location is deprecated, use --destination instead")
				cfg.Destination = oldDestination
			}

			glog.V(2).Infof("\n%s\n", describe.Config(cfg))

			err := docker.CheckReachable(cfg)
			if err != nil {
//.........这里部分代码省略.........

// New returns the instance of STI builder strategy for the given config.
// If the layeredBuilder parameter is specified, then the builder provided will
// be used for the case that the base Docker image does not have 'tar' or 'bash'
// installed.
func New(config *api.Config, overrides build.Overrides) (*STI, error) {
	docker, err := dockerpkg.New(config.DockerConfig, config.PullAuthentication)
	if err != nil {
		return nil, err
	}
	var incrementalDocker dockerpkg.Docker
	if config.Incremental {
		incrementalDocker, err = dockerpkg.New(config.DockerConfig, config.IncrementalAuthentication)
		if err != nil {
			return nil, err
		}
	}

	inst := scripts.NewInstaller(config.BuilderImage, config.ScriptsURL, config.ScriptDownloadProxyConfig, docker, config.PullAuthentication)
	tarHandler := tar.New()
	tarHandler.SetExclusionPattern(regexp.MustCompile(config.ExcludeRegExp))

	builder := &STI{
		installer:              inst,
		config:                 config,
		docker:                 docker,
		incrementalDocker:      incrementalDocker,
		git:                    git.New(),
		fs:                     util.NewFileSystem(),
		tar:                    tarHandler,
		callbackInvoker:        util.NewCallbackInvoker(),
		requiredScripts:        []string{api.Assemble, api.Run},
		optionalScripts:        []string{api.SaveArtifacts},
		optionalRuntimeScripts: []string{api.AssembleRuntime},
		externalScripts:        map[string]bool{},
		installedScripts:       map[string]bool{},
		scriptsURL:             map[string]string{},
	}

	if len(config.RuntimeImage) > 0 {
		builder.runtimeInstaller = scripts.NewInstaller(config.RuntimeImage, config.ScriptsURL, config.ScriptDownloadProxyConfig, docker, config.PullAuthentication)

		builder.runtimeDocker, err = dockerpkg.New(config.DockerConfig, config.RuntimeAuthentication)
		if err != nil {
			return builder, err
		}
	}

	// The sources are downloaded using the Git downloader.
	// TODO: Add more SCM in future.
	// TODO: explicit decision made to customize processing for usage specifically vs.
	// leveraging overrides; also, we ultimately want to simplify s2i usage a good bit,
	// which would lead to replacing this quick short circuit (so this change is tactical)
	builder.source = overrides.Downloader
	if builder.source == nil && !config.Usage {
		downloader, sourceURL, err := scm.DownloaderForSource(config.Source, config.ForceCopy)
		if err != nil {
			return nil, err
		}
		builder.source = downloader
		config.Source = sourceURL
	}

	builder.garbage = build.NewDefaultCleaner(builder.fs, builder.docker)
	builder.layered, err = layered.New(config, builder, overrides)

	// Set interfaces
	builder.preparer = builder
	// later on, if we support say .gitignore func in addition to .dockerignore func, setting
	// ignorer will be based on config setting
	builder.ignorer = &ignore.DockerIgnorer{}
	builder.artifacts = builder
	builder.scripts = builder

	builder.postExecutor = builder
	builder.initPostExecutorSteps()

	return builder, err
}

func newCmdBuild(cfg *api.Config) *cobra.Command {
	useConfig := false
	oldScriptsFlag := ""
	oldDestination := ""

	buildCmd := &cobra.Command{
		Use:   "build <source> <image> [<tag>]",
		Short: "Build a new image",
		Long:  "Build a new Docker image named <tag> (if provided) from a source repository and base image.",
		Example: `
# Build an application Docker image from a Git repository
$ s2i build git://github.com/openshift/ruby-hello-world centos/ruby-22-centos7 hello-world-app

# Build from a local directory
$ s2i build . centos/ruby-22-centos7 hello-world-app
`,
		Run: func(cmd *cobra.Command, args []string) {
			go cmdutil.InstallDumpOnSignal()

			// Attempt to restore the build command from the configuration file
			if useConfig {
				config.Restore(cfg, cmd)
			}

			// If user specifies the arguments, then we override the stored ones
			if len(args) >= 2 {
				cfg.Source = args[0]
				cfg.BuilderImage = args[1]
				if len(args) >= 3 {
					cfg.Tag = args[2]
				}
			}

			if cfg.ForcePull {
				glog.Warning("DEPRECATED: The '--force-pull' option is deprecated. Use '--pull-policy' instead")
			}

			if len(cfg.BuilderPullPolicy) == 0 {
				cfg.BuilderPullPolicy = api.DefaultBuilderPullPolicy
			}

			if errs := validation.ValidateConfig(cfg); len(errs) > 0 {
				for _, e := range errs {
					fmt.Fprintf(os.Stderr, "ERROR: %s\n", e)
				}
				fmt.Println()
				cmd.Help()
				os.Exit(1)
			}

			// Persists the current command line options and config into .stifile
			if useConfig {
				config.Save(cfg, cmd)
			}

			// Attempt to read the .dockercfg and extract the authentication for
			// docker pull
			if r, err := os.Open(cfg.DockerCfgPath); err == nil {
				auths := docker.LoadImageRegistryAuth(r)
				cfg.PullAuthentication = docker.GetImageRegistryAuth(auths, cfg.BuilderImage)
				if cfg.Incremental {
					cfg.IncrementalAuthentication = docker.GetImageRegistryAuth(auths, cfg.Tag)
				}
			}

			cfg.Environment = map[string]string{}
			if len(cfg.EnvironmentFile) > 0 {
				result, err := util.ReadEnvironmentFile(cfg.EnvironmentFile)
				if err != nil {
					glog.Warningf("Unable to read environment file %q: %v", cfg.EnvironmentFile, err)
				} else {
					cfg.Environment = result
				}
			}

			envs, err := cmdutil.ParseEnvs(cmd, "env")
			checkErr(err)
			for k, v := range envs {
				cfg.Environment[k] = v
			}

			if len(oldScriptsFlag) != 0 {
				glog.Warning("DEPRECATED: Flag --scripts is deprecated, use --scripts-url instead")
				cfg.ScriptsURL = oldScriptsFlag
			}
			if len(oldDestination) != 0 {
				glog.Warning("DEPRECATED: Flag --location is deprecated, use --destination instead")
				cfg.Destination = oldDestination
			}

			if glog.V(2) {
				fmt.Printf("\n%s\n", describe.DescribeConfig(cfg))
			}

			if !docker.IsReachable(cfg) {
				glog.Fatalf("Unable to connect to Docker daemon. Please set the DOCKER_HOST or make sure the Docker socket %q exists", cfg.DockerConfig.Endpoint)
			}

			builder, err := strategies.GetStrategy(cfg)
			checkErr(err)
//.........这里部分代码省略.........

func newCmdBuild(cfg *api.Config) *cobra.Command {
	useConfig := false
	oldScriptsFlag := ""
	oldDestination := ""

	buildCmd := &cobra.Command{
		Use:   "build <source> <image> [<tag>]",
		Short: "Build a new image",
		Long:  "Build a new Docker image named <tag> (if provided) from a source repository and base image.",
		Run: func(cmd *cobra.Command, args []string) {
			go func() {
				for {
					sigs := make(chan os.Signal, 1)
					signal.Notify(sigs, syscall.SIGQUIT)
					buf := make([]byte, 1<<20)
					for {
						<-sigs
						runtime.Stack(buf, true)
						if file, err := ioutil.TempFile(os.TempDir(), "sti_dump"); err == nil {
							defer file.Close()
							file.Write(buf)
						}
						glog.Infof("=== received SIGQUIT ===\n*** goroutine dump...\n%s\n*** end\n", buf)
					}
				}
			}()
			// Attempt to restore the build command from the configuration file
			if useConfig {
				config.Restore(cfg, cmd)
			}

			// If user specifies the arguments, then we override the stored ones
			if len(args) >= 2 {
				cfg.Source = args[0]
				cfg.BuilderImage = args[1]
				if len(args) >= 3 {
					cfg.Tag = args[2]
				}
			}

			if len(validation.ValidateConfig(cfg)) != 0 {
				cmd.Help()
				os.Exit(1)
			}

			// Persists the current command line options and config into .stifile
			if useConfig {
				config.Save(cfg, cmd)
			}

			// Attempt to read the .dockercfg and extract the authentication for
			// docker pull
			if r, err := os.Open(cfg.DockerCfgPath); err == nil {
				cfg.PullAuthentication = docker.GetImageRegistryAuth(r, cfg.BuilderImage)
			}

			cfg.Environment = map[string]string{}

			if len(cfg.EnvironmentFile) > 0 {
				result, err := util.ReadEnvironmentFile(cfg.EnvironmentFile)
				if err != nil {
					glog.Warningf("Unable to read %s: %v", cfg.EnvironmentFile, err)
				} else {
					cfg.Environment = result
				}
			}

			envs, err := parseEnvs(cmd, "env")
			checkErr(err)
			for k, v := range envs {
				cfg.Environment[k] = v
			}

			if len(oldScriptsFlag) != 0 {
				glog.Warning("Flag --scripts is deprecated, use --scripts-url instead")
				cfg.ScriptsURL = oldScriptsFlag
			}
			if len(oldDestination) != 0 {
				glog.Warning("Flag --location is deprecated, use --destination instead")
				cfg.Destination = oldDestination
			}

			if glog.V(2) {
				fmt.Printf("\n%s\n", describe.DescribeConfig(cfg))
			}
			builder, err := strategies.GetStrategy(cfg)
			checkErr(err)
			result, err := builder.Build(cfg)
			checkErr(err)

			for _, message := range result.Messages {
				glog.V(1).Infof(message)
			}

		},
	}

	buildCmd.Flags().BoolVarP(&(cfg.Quiet), "quiet", "q", false, "Operate quietly. Suppress all non-error output.")
	buildCmd.Flags().BoolVar(&(cfg.Incremental), "incremental", false, "Perform an incremental build")
	buildCmd.Flags().BoolVar(&(cfg.RemovePreviousImage), "rm", false, "Remove the previous image during incremental builds")
//.........这里部分代码省略.........

// Download downloads the application source code from the Git repository
// and checkout the Ref specified in the config.
func (c *Clone) Download(config *api.Config) (*api.SourceInfo, error) {
	targetSourceDir := filepath.Join(config.WorkingDir, api.Source)
	config.WorkingSourceDir = targetSourceDir

	ok, err := c.ValidCloneSpec(config.Source)
	if err != nil {
		return nil, err
	}
	if !ok {
		glog.Errorf("Clone.Download was passed an invalid source %s", config.Source)
		return nil, fmt.Errorf("invalid source %s", config.Source)
	}

	ref := "HEAD"
	if config.Ref != "" {
		ref = config.Ref
	}

	if strings.HasPrefix(config.Source, "file://") {
		s := strings.TrimPrefix(config.Source, "file://")

		if util.UsingCygwinGit {
			var err error
			s, err = util.ToSlashCygwin(s)
			if err != nil {
				glog.V(0).Infof("error: Cygwin path conversion failed: %v", err)
				return nil, err
			}
		}
		config.Source = "file://" + s
	}

	if len(config.ContextDir) > 0 {
		targetSourceDir = filepath.Join(config.WorkingDir, api.ContextTmp)
		glog.V(1).Infof("Downloading %q (%q) ...", config.Source, config.ContextDir)
	} else {
		glog.V(1).Infof("Downloading %q ...", config.Source)
	}

	if !config.IgnoreSubmodules {
		glog.V(2).Infof("Cloning sources into %q", targetSourceDir)
	} else {
		glog.V(2).Infof("Cloning sources (ignoring submodules) into %q", targetSourceDir)
	}

	cloneConfig := api.CloneConfig{Quiet: true}
	err = c.Clone(config.Source, targetSourceDir, cloneConfig)
	if err != nil {
		glog.V(0).Infof("error: git clone failed: %v", err)
		return nil, err
	}

	err = c.Checkout(targetSourceDir, ref)
	if err != nil {
		return nil, err
	}
	glog.V(1).Infof("Checked out %q", ref)
	if !config.IgnoreSubmodules {
		err = c.SubmoduleUpdate(targetSourceDir, true, true)
		if err != nil {
			return nil, err
		}
		glog.V(1).Infof("Updated submodules for %q", ref)
	}

	// Record Git's knowledge about file permissions
	if runtime.GOOS == "windows" {
		filemodes, err := c.LsTree(filepath.Join(targetSourceDir, config.ContextDir), ref, true)
		if err != nil {
			return nil, err
		}
		for _, filemode := range filemodes {
			c.Chmod(filepath.Join(targetSourceDir, config.ContextDir, filemode.Name()), os.FileMode(filemode.Mode())&os.ModePerm)
		}
	}

	info := c.GetInfo(targetSourceDir)
	if len(config.ContextDir) > 0 {
		originalTargetDir := filepath.Join(config.WorkingDir, api.Source)
		c.RemoveDirectory(originalTargetDir)
		path := filepath.Join(targetSourceDir, config.ContextDir)
		err := c.CopyContents(path, originalTargetDir)
		if err != nil {
			return nil, err
		}
		c.RemoveDirectory(targetSourceDir)
	}

	if len(config.ContextDir) > 0 {
		info.ContextDir = config.ContextDir
	}

	return info, nil
}