// DetectContextFromRemoteURL returns a context and in certain cases the name of the dockerfile to be used
// irrespective of user input.
// progressReader is only used if remoteURL is actually a URL (not empty, and not a Git endpoint).
func DetectContextFromRemoteURL(r io.ReadCloser, remoteURL string, createProgressReader func(in io.ReadCloser) io.ReadCloser) (context builder.ModifiableContext, dockerfileName string, err error) {
	switch {
	case remoteURL == "":
		context, err = builder.MakeTarSumContext(r)
	case urlutil.IsGitURL(remoteURL):
		context, err = builder.MakeGitContext(remoteURL)
	case urlutil.IsURL(remoteURL):
		context, err = builder.MakeRemoteContext(remoteURL, map[string]func(io.ReadCloser) (io.ReadCloser, error){
			httputils.MimeTypes.TextPlain: func(rc io.ReadCloser) (io.ReadCloser, error) {
				dockerfile, err := ioutil.ReadAll(rc)
				if err != nil {
					return nil, err
				}

				// dockerfileName is set to signal that the remote was interpreted as a single Dockerfile, in which case the caller
				// should use dockerfileName as the new name for the Dockerfile, irrespective of any other user input.
				dockerfileName = api.DefaultDockerfileName

				// TODO: return a context without tarsum
				return archive.Generate(dockerfileName, string(dockerfile))
			},
			// fallback handler (tar context)
			"": func(rc io.ReadCloser) (io.ReadCloser, error) {
				return createProgressReader(rc), nil
			},
		})
	default:
		err = fmt.Errorf("remoteURL (%s) could not be recognized as URL", remoteURL)
	}
	return
}

// CmdBuild builds a new image from the source code at a given path.
//
// If '-' is provided instead of a path or URL, Docker will build an image from either a Dockerfile or tar archive read from STDIN.
//
// Usage: docker build [OPTIONS] PATH | URL | -
func (cli *DockerCli) CmdBuild(args ...string) error {
	cmd := Cli.Subcmd("build", []string{"PATH | URL | -"}, Cli.DockerCommands["build"].Description, true)
	flTags := opts.NewListOpts(validateTag)
	cmd.Var(&flTags, []string{"t", "-tag"}, "Name and optionally a tag in the 'name:tag' format")
	suppressOutput := cmd.Bool([]string{"q", "-quiet"}, false, "Suppress the build output and print image ID on success")
	noCache := cmd.Bool([]string{"-no-cache"}, false, "Do not use cache when building the image")
	rm := cmd.Bool([]string{"-rm"}, true, "Remove intermediate containers after a successful build")
	forceRm := cmd.Bool([]string{"-force-rm"}, false, "Always remove intermediate containers")
	pull := cmd.Bool([]string{"-pull"}, false, "Always attempt to pull a newer version of the image")
	dockerfileName := cmd.String([]string{"f", "-file"}, "", "Name of the Dockerfile (Default is 'PATH/Dockerfile')")
	flMemoryString := cmd.String([]string{"m", "-memory"}, "", "Memory limit")
	flMemorySwap := cmd.String([]string{"-memory-swap"}, "", "Swap limit equal to memory plus swap: '-1' to enable unlimited swap")
	flShmSize := cmd.String([]string{"-shm-size"}, "", "Size of /dev/shm, default value is 64MB")
	flCPUShares := cmd.Int64([]string{"#c", "-cpu-shares"}, 0, "CPU shares (relative weight)")
	flCPUPeriod := cmd.Int64([]string{"-cpu-period"}, 0, "Limit the CPU CFS (Completely Fair Scheduler) period")
	flCPUQuota := cmd.Int64([]string{"-cpu-quota"}, 0, "Limit the CPU CFS (Completely Fair Scheduler) quota")
	flCPUSetCpus := cmd.String([]string{"-cpuset-cpus"}, "", "CPUs in which to allow execution (0-3, 0,1)")
	flCPUSetMems := cmd.String([]string{"-cpuset-mems"}, "", "MEMs in which to allow execution (0-3, 0,1)")
	flCgroupParent := cmd.String([]string{"-cgroup-parent"}, "", "Optional parent cgroup for the container")
	flBuildArg := opts.NewListOpts(runconfigopts.ValidateEnv)
	cmd.Var(&flBuildArg, []string{"-build-arg"}, "Set build-time variables")
	isolation := cmd.String([]string{"-isolation"}, "", "Container isolation level")

	ulimits := make(map[string]*units.Ulimit)
	flUlimits := runconfigopts.NewUlimitOpt(&ulimits)
	cmd.Var(flUlimits, []string{"-ulimit"}, "Ulimit options")

	cmd.Require(flag.Exact, 1)

	// For trusted pull on "FROM <image>" instruction.
	addTrustedFlags(cmd, true)

	cmd.ParseFlags(args, true)

	var (
		context  io.ReadCloser
		isRemote bool
		err      error
	)

	_, err = exec.LookPath("git")
	hasGit := err == nil

	specifiedContext := cmd.Arg(0)

	var (
		contextDir    string
		tempDir       string
		relDockerfile string
		progBuff      io.Writer
		buildBuff     io.Writer
	)

	progBuff = cli.out
	buildBuff = cli.out
	if *suppressOutput {
		progBuff = bytes.NewBuffer(nil)
		buildBuff = bytes.NewBuffer(nil)
	}

	switch {
	case specifiedContext == "-":
		context, relDockerfile, err = getContextFromReader(cli.in, *dockerfileName)
	case urlutil.IsGitURL(specifiedContext) && hasGit:
		tempDir, relDockerfile, err = getContextFromGitURL(specifiedContext, *dockerfileName)
	case urlutil.IsURL(specifiedContext):
		context, relDockerfile, err = getContextFromURL(progBuff, specifiedContext, *dockerfileName)
	default:
		contextDir, relDockerfile, err = getContextFromLocalDir(specifiedContext, *dockerfileName)
	}

	if err != nil {
		if *suppressOutput && urlutil.IsURL(specifiedContext) {
			fmt.Fprintln(cli.err, progBuff)
		}
		return fmt.Errorf("unable to prepare context: %s", err)
	}

	if tempDir != "" {
		defer os.RemoveAll(tempDir)
		contextDir = tempDir
	}

	if context == nil {
		// And canonicalize dockerfile name to a platform-independent one
		relDockerfile, err = archive.CanonicalTarNameForPath(relDockerfile)
		if err != nil {
			return fmt.Errorf("cannot canonicalize dockerfile path %s: %v", relDockerfile, err)
		}

		f, err := os.Open(filepath.Join(contextDir, ".dockerignore"))
		if err != nil && !os.IsNotExist(err) {
			return err
		}

//.........这里部分代码省略.........

// CmdBuild builds a new image from the source code at a given path.
//
// If '-' is provided instead of a path or URL, Docker will build an image from either a Dockerfile or tar archive read from STDIN.
//
// Usage: docker build [OPTIONS] PATH | URL | -
func (cli *DockerCli) CmdBuild(args ...string) error {
	cmd := cli.Subcmd("build", "PATH | URL | -", "Build a new image from the source code at PATH", true)
	tag := cmd.String([]string{"t", "-tag"}, "", "Repository name (and optionally a tag) for the image")
	suppressOutput := cmd.Bool([]string{"q", "-quiet"}, false, "Suppress the verbose output generated by the containers")
	noCache := cmd.Bool([]string{"#no-cache", "-no-cache"}, false, "Do not use cache when building the image")
	rm := cmd.Bool([]string{"#rm", "-rm"}, true, "Remove intermediate containers after a successful build")
	forceRm := cmd.Bool([]string{"-force-rm"}, false, "Always remove intermediate containers")
	pull := cmd.Bool([]string{"-pull"}, false, "Always attempt to pull a newer version of the image")
	dockerfileName := cmd.String([]string{"f", "-file"}, "", "Name of the Dockerfile (Default is 'PATH/Dockerfile')")
	flMemoryString := cmd.String([]string{"m", "-memory"}, "", "Memory limit")
	flMemorySwap := cmd.String([]string{"-memory-swap"}, "", "Total memory (memory + swap), '-1' to disable swap")
	flCPUShares := cmd.Int64([]string{"c", "-cpu-shares"}, 0, "CPU shares (relative weight)")
	flCpuQuota := cmd.Int64([]string{"-cpu-quota"}, 0, "Limit the CPU CFS (Completely Fair Scheduler) quota")
	flCPUSetCpus := cmd.String([]string{"-cpuset-cpus"}, "", "CPUs in which to allow execution (0-3, 0,1)")
	flCPUSetMems := cmd.String([]string{"-cpuset-mems"}, "", "MEMs in which to allow execution (0-3, 0,1)")
	flCgroupParent := cmd.String([]string{"-cgroup-parent"}, "", "Optional parent cgroup for the container")

	cmd.Require(flag.Exact, 1)
	cmd.ParseFlags(args, true)

	var (
		context  archive.Archive
		isRemote bool
		err      error
	)

	_, err = exec.LookPath("git")
	hasGit := err == nil
	if cmd.Arg(0) == "-" {
		// As a special case, 'docker build -' will build from either an empty context with the
		// contents of stdin as a Dockerfile, or a tar-ed context from stdin.
		buf := bufio.NewReader(cli.in)
		magic, err := buf.Peek(tarHeaderSize)
		if err != nil && err != io.EOF {
			return fmt.Errorf("failed to peek context header from STDIN: %v", err)
		}
		if !archive.IsArchive(magic) {
			dockerfile, err := ioutil.ReadAll(buf)
			if err != nil {
				return fmt.Errorf("failed to read Dockerfile from STDIN: %v", err)
			}

			// -f option has no meaning when we're reading it from stdin,
			// so just use our default Dockerfile name
			*dockerfileName = api.DefaultDockerfileName
			context, err = archive.Generate(*dockerfileName, string(dockerfile))
		} else {
			context = ioutil.NopCloser(buf)
		}
	} else if urlutil.IsURL(cmd.Arg(0)) && (!urlutil.IsGitURL(cmd.Arg(0)) || !hasGit) {
		isRemote = true
	} else {
		root := cmd.Arg(0)
		if urlutil.IsGitURL(root) {
			root, err = utils.GitClone(root)
			if err != nil {
				return err
			}
			defer os.RemoveAll(root)
		}
		if _, err := os.Stat(root); err != nil {
			return err
		}

		absRoot, err := filepath.Abs(root)
		if err != nil {
			return err
		}

		filename := *dockerfileName // path to Dockerfile

		if *dockerfileName == "" {
			// No -f/--file was specified so use the default
			*dockerfileName = api.DefaultDockerfileName
			filename = filepath.Join(absRoot, *dockerfileName)

			// Just to be nice ;-) look for 'dockerfile' too but only
			// use it if we found it, otherwise ignore this check
			if _, err = os.Lstat(filename); os.IsNotExist(err) {
				tmpFN := path.Join(absRoot, strings.ToLower(*dockerfileName))
				if _, err = os.Lstat(tmpFN); err == nil {
					*dockerfileName = strings.ToLower(*dockerfileName)
					filename = tmpFN
				}
			}
		}

		origDockerfile := *dockerfileName // used for error msg
		if filename, err = filepath.Abs(filename); err != nil {
			return err
		}

		// Verify that 'filename' is within the build context
		filename, err = symlink.FollowSymlinkInScope(filename, absRoot)
		if err != nil {
//.........这里部分代码省略.........

// Build is the main interface of the package, it gathers the Builder
// struct and calls builder.Run() to do all the real build job.
func Build(d *daemon.Daemon, buildConfig *Config) error {
	var (
		repoName string
		tag      string
		context  io.ReadCloser
	)
	sf := streamformatter.NewJSONStreamFormatter()

	repoName, tag = parsers.ParseRepositoryTag(buildConfig.RepoName)
	if repoName != "" {
		if err := registry.ValidateRepositoryName(repoName); err != nil {
			return err
		}
		if len(tag) > 0 {
			if err := tags.ValidateTagName(tag); err != nil {
				return err
			}
		}
	}

	if buildConfig.RemoteURL == "" {
		context = ioutil.NopCloser(buildConfig.Context)
	} else if urlutil.IsGitURL(buildConfig.RemoteURL) {
		root, err := utils.GitClone(buildConfig.RemoteURL)
		if err != nil {
			return err
		}
		defer os.RemoveAll(root)

		c, err := archive.Tar(root, archive.Uncompressed)
		if err != nil {
			return err
		}
		context = c
	} else if urlutil.IsURL(buildConfig.RemoteURL) {
		f, err := httputils.Download(buildConfig.RemoteURL)
		if err != nil {
			return fmt.Errorf("Error downloading remote context %s: %v", buildConfig.RemoteURL, err)
		}
		defer f.Body.Close()
		ct := f.Header.Get("Content-Type")
		clen := int(f.ContentLength)
		contentType, bodyReader, err := inspectResponse(ct, f.Body, clen)

		defer bodyReader.Close()

		if err != nil {
			return fmt.Errorf("Error detecting content type for remote %s: %v", buildConfig.RemoteURL, err)
		}
		if contentType == httputils.MimeTypes.TextPlain {
			dockerFile, err := ioutil.ReadAll(bodyReader)
			if err != nil {
				return err
			}

			// When we're downloading just a Dockerfile put it in
			// the default name - don't allow the client to move/specify it
			buildConfig.DockerfileName = api.DefaultDockerfileName

			c, err := archive.Generate(buildConfig.DockerfileName, string(dockerFile))
			if err != nil {
				return err
			}
			context = c
		} else {
			// Pass through - this is a pre-packaged context, presumably
			// with a Dockerfile with the right name inside it.
			prCfg := progressreader.Config{
				In:        bodyReader,
				Out:       buildConfig.Stdout,
				Formatter: sf,
				Size:      clen,
				NewLines:  true,
				ID:        "Downloading context",
				Action:    buildConfig.RemoteURL,
			}
			context = progressreader.New(prCfg)
		}
	}

	defer context.Close()

	builder := &builder{
		Daemon: d,
		OutStream: &streamformatter.StdoutFormater{
			Writer:          buildConfig.Stdout,
			StreamFormatter: sf,
		},
		ErrStream: &streamformatter.StderrFormater{
			Writer:          buildConfig.Stdout,
			StreamFormatter: sf,
		},
		Verbose:         !buildConfig.SuppressOutput,
		UtilizeCache:    !buildConfig.NoCache,
		Remove:          buildConfig.Remove,
		ForceRemove:     buildConfig.ForceRemove,
		Pull:            buildConfig.Pull,
		OutOld:          buildConfig.Stdout,
//.........这里部分代码省略.........

// CmdBuild builds a new image from the source code at a given path.
//
// If '-' is provided instead of a path or URL, Docker will build an image from either a Dockerfile or tar archive read from STDIN.
//
// Usage: docker build [OPTIONS] PATH | URL | -
func (cli *DockerCli) CmdBuild(args ...string) error {
	cmd := Cli.Subcmd("build", []string{"PATH | URL | -"}, Cli.DockerCommands["build"].Description, true)
	flTags := opts.NewListOpts(validateTag)
	cmd.Var(&flTags, []string{"t", "-tag"}, "Name and optionally a tag in the 'name:tag' format")
	suppressOutput := cmd.Bool([]string{"q", "-quiet"}, false, "Suppress the verbose output generated by the containers")
	noCache := cmd.Bool([]string{"#no-cache", "-no-cache"}, false, "Do not use cache when building the image")
	rm := cmd.Bool([]string{"#rm", "-rm"}, true, "Remove intermediate containers after a successful build")
	forceRm := cmd.Bool([]string{"-force-rm"}, false, "Always remove intermediate containers")
	pull := cmd.Bool([]string{"-pull"}, false, "Always attempt to pull a newer version of the image")
	dockerfileName := cmd.String([]string{"f", "-file"}, "", "Name of the Dockerfile (Default is 'PATH/Dockerfile')")
	flMemoryString := cmd.String([]string{"m", "-memory"}, "", "Memory limit")
	flMemorySwap := cmd.String([]string{"-memory-swap"}, "", "Total memory (memory + swap), '-1' to disable swap")
	flCPUShares := cmd.Int64([]string{"#c", "-cpu-shares"}, 0, "CPU shares (relative weight)")
	flCPUPeriod := cmd.Int64([]string{"-cpu-period"}, 0, "Limit the CPU CFS (Completely Fair Scheduler) period")
	flCPUQuota := cmd.Int64([]string{"-cpu-quota"}, 0, "Limit the CPU CFS (Completely Fair Scheduler) quota")
	flCPUSetCpus := cmd.String([]string{"-cpuset-cpus"}, "", "CPUs in which to allow execution (0-3, 0,1)")
	flCPUSetMems := cmd.String([]string{"-cpuset-mems"}, "", "MEMs in which to allow execution (0-3, 0,1)")
	flCgroupParent := cmd.String([]string{"-cgroup-parent"}, "", "Optional parent cgroup for the container")
	flBuildArg := opts.NewListOpts(opts.ValidateEnv)
	cmd.Var(&flBuildArg, []string{"-build-arg"}, "Set build-time variables")

	ulimits := make(map[string]*ulimit.Ulimit)
	flUlimits := opts.NewUlimitOpt(&ulimits)
	cmd.Var(flUlimits, []string{"-ulimit"}, "Ulimit options")

	cmd.Require(flag.Exact, 1)

	// For trusted pull on "FROM <image>" instruction.
	addTrustedFlags(cmd, true)

	cmd.ParseFlags(args, true)

	var (
		context  io.ReadCloser
		isRemote bool
		err      error
	)

	_, err = exec.LookPath("git")
	hasGit := err == nil

	specifiedContext := cmd.Arg(0)

	var (
		contextDir    string
		tempDir       string
		relDockerfile string
	)

	switch {
	case specifiedContext == "-":
		tempDir, relDockerfile, err = getContextFromReader(cli.in, *dockerfileName)
	case urlutil.IsGitURL(specifiedContext) && hasGit:
		tempDir, relDockerfile, err = getContextFromGitURL(specifiedContext, *dockerfileName)
	case urlutil.IsURL(specifiedContext):
		tempDir, relDockerfile, err = getContextFromURL(cli.out, specifiedContext, *dockerfileName)
	default:
		contextDir, relDockerfile, err = getContextFromLocalDir(specifiedContext, *dockerfileName)
	}

	if err != nil {
		return fmt.Errorf("unable to prepare context: %s", err)
	}

	if tempDir != "" {
		defer os.RemoveAll(tempDir)
		contextDir = tempDir
	}

	// Resolve the FROM lines in the Dockerfile to trusted digest references
	// using Notary. On a successful build, we must tag the resolved digests
	// to the original name specified in the Dockerfile.
	newDockerfile, resolvedTags, err := rewriteDockerfileFrom(filepath.Join(contextDir, relDockerfile), cli.trustedReference)
	if err != nil {
		return fmt.Errorf("unable to process Dockerfile: %v", err)
	}
	defer newDockerfile.Close()

	// And canonicalize dockerfile name to a platform-independent one
	relDockerfile, err = archive.CanonicalTarNameForPath(relDockerfile)
	if err != nil {
		return fmt.Errorf("cannot canonicalize dockerfile path %s: %v", relDockerfile, err)
	}

	f, err := os.Open(filepath.Join(contextDir, ".dockerignore"))
	if err != nil && !os.IsNotExist(err) {
		return err
	}

	var excludes []string
	if err == nil {
		excludes, err = utils.ReadDockerIgnore(f)
		if err != nil {
			return err
		}
//.........这里部分代码省略.........

func (b *BuilderJob) CmdBuild(job *engine.Job) engine.Status {
	if len(job.Args) != 0 {
		return job.Errorf("Usage: %s\n", job.Name)
	}
	var (
		dockerfileName = job.Getenv("dockerfile")
		remoteURL      = job.Getenv("remote")
		repoName       = job.Getenv("t")
		suppressOutput = job.GetenvBool("q")
		noCache        = job.GetenvBool("nocache")
		rm             = job.GetenvBool("rm")
		forceRm        = job.GetenvBool("forcerm")
		pull           = job.GetenvBool("pull")
		authConfig     = &registry.AuthConfig{}
		configFile     = &registry.ConfigFile{}
		tag            string
		context        io.ReadCloser
	)

	job.GetenvJson("authConfig", authConfig)
	job.GetenvJson("configFile", configFile)

	repoName, tag = parsers.ParseRepositoryTag(repoName)
	if repoName != "" {
		if err := registry.ValidateRepositoryName(repoName); err != nil {
			return job.Error(err)
		}
		if len(tag) > 0 {
			if err := graph.ValidateTagName(tag); err != nil {
				return job.Error(err)
			}
		}
	}

	if remoteURL == "" {
		context = ioutil.NopCloser(job.Stdin)
	} else if urlutil.IsGitURL(remoteURL) {
		if !urlutil.IsGitTransport(remoteURL) {
			remoteURL = "https://" + remoteURL
		}
		root, err := ioutil.TempDir("", "docker-build-git")
		if err != nil {
			return job.Error(err)
		}
		defer os.RemoveAll(root)

		if output, err := exec.Command("git", "clone", "--recursive", remoteURL, root).CombinedOutput(); err != nil {
			return job.Errorf("Error trying to use git: %s (%s)", err, output)
		}

		c, err := archive.Tar(root, archive.Uncompressed)
		if err != nil {
			return job.Error(err)
		}
		context = c
	} else if urlutil.IsURL(remoteURL) {
		f, err := utils.Download(remoteURL)
		if err != nil {
			return job.Error(err)
		}
		defer f.Body.Close()
		dockerFile, err := ioutil.ReadAll(f.Body)
		if err != nil {
			return job.Error(err)
		}

		// When we're downloading just a Dockerfile put it in
		// the default name - don't allow the client to move/specify it
		dockerfileName = api.DefaultDockerfileName

		c, err := archive.Generate(dockerfileName, string(dockerFile))
		if err != nil {
			return job.Error(err)
		}
		context = c
	}
	defer context.Close()

	sf := utils.NewStreamFormatter(job.GetenvBool("json"))

	builder := &Builder{
		Daemon: b.Daemon,
		Engine: b.Engine,
		OutStream: &utils.StdoutFormater{
			Writer:          job.Stdout,
			StreamFormatter: sf,
		},
		ErrStream: &utils.StderrFormater{
			Writer:          job.Stdout,
			StreamFormatter: sf,
		},
		Verbose:         !suppressOutput,
		UtilizeCache:    !noCache,
		Remove:          rm,
		ForceRemove:     forceRm,
		Pull:            pull,
		OutOld:          job.Stdout,
		StreamFormatter: sf,
		AuthConfig:      authConfig,
		AuthConfigFile:  configFile,
//.........这里部分代码省略.........

func runBuild(dockerCli *command.DockerCli, options buildOptions) error {

	var (
		buildCtx io.ReadCloser
		err      error
	)

	specifiedContext := options.context

	var (
		contextDir    string
		tempDir       string
		relDockerfile string
		progBuff      io.Writer
		buildBuff     io.Writer
	)

	progBuff = dockerCli.Out()
	buildBuff = dockerCli.Out()
	if options.quiet {
		progBuff = bytes.NewBuffer(nil)
		buildBuff = bytes.NewBuffer(nil)
	}

	switch {
	case specifiedContext == "-":
		buildCtx, relDockerfile, err = builder.GetContextFromReader(dockerCli.In(), options.dockerfileName)
	case urlutil.IsGitURL(specifiedContext):
		tempDir, relDockerfile, err = builder.GetContextFromGitURL(specifiedContext, options.dockerfileName)
	case urlutil.IsURL(specifiedContext):
		buildCtx, relDockerfile, err = builder.GetContextFromURL(progBuff, specifiedContext, options.dockerfileName)
	default:
		contextDir, relDockerfile, err = builder.GetContextFromLocalDir(specifiedContext, options.dockerfileName)
	}

	if err != nil {
		if options.quiet && urlutil.IsURL(specifiedContext) {
			fmt.Fprintln(dockerCli.Err(), progBuff)
		}
		return fmt.Errorf("unable to prepare context: %s", err)
	}

	if tempDir != "" {
		defer os.RemoveAll(tempDir)
		contextDir = tempDir
	}

	if buildCtx == nil {
		// And canonicalize dockerfile name to a platform-independent one
		relDockerfile, err = archive.CanonicalTarNameForPath(relDockerfile)
		if err != nil {
			return fmt.Errorf("cannot canonicalize dockerfile path %s: %v", relDockerfile, err)
		}

		f, err := os.Open(filepath.Join(contextDir, ".dockerignore"))
		if err != nil && !os.IsNotExist(err) {
			return err
		}
		defer f.Close()

		var excludes []string
		if err == nil {
			excludes, err = dockerignore.ReadAll(f)
			if err != nil {
				return err
			}
		}

		if err := builder.ValidateContextDirectory(contextDir, excludes); err != nil {
			return fmt.Errorf("Error checking context: '%s'.", err)
		}

		// If .dockerignore mentions .dockerignore or the Dockerfile
		// then make sure we send both files over to the daemon
		// because Dockerfile is, obviously, needed no matter what, and
		// .dockerignore is needed to know if either one needs to be
		// removed. The daemon will remove them for us, if needed, after it
		// parses the Dockerfile. Ignore errors here, as they will have been
		// caught by validateContextDirectory above.
		var includes = []string{"."}
		keepThem1, _ := fileutils.Matches(".dockerignore", excludes)
		keepThem2, _ := fileutils.Matches(relDockerfile, excludes)
		if keepThem1 || keepThem2 {
			includes = append(includes, ".dockerignore", relDockerfile)
		}

		buildCtx, err = archive.TarWithOptions(contextDir, &archive.TarOptions{
			Compression:     archive.Uncompressed,
			ExcludePatterns: excludes,
			IncludeFiles:    includes,
		})
		if err != nil {
			return err
		}
	}

	ctx := context.Background()

	var resolvedTags []*resolvedTag
	if command.IsTrusted() {
//.........这里部分代码省略.........

func Build(d *daemon.Daemon, buildConfig *Config) error {
	var (
		repoName string
		tag      string
		context  io.ReadCloser
	)

	repoName, tag = parsers.ParseRepositoryTag(buildConfig.RepoName)
	if repoName != "" {
		if err := registry.ValidateRepositoryName(repoName); err != nil {
			return err
		}
		if len(tag) > 0 {
			if err := tags.ValidateTagName(tag); err != nil {
				return err
			}
		}
	}

	if buildConfig.RemoteURL == "" {
		context = ioutil.NopCloser(buildConfig.Context)
	} else if urlutil.IsGitURL(buildConfig.RemoteURL) {
		root, err := utils.GitClone(buildConfig.RemoteURL)
		if err != nil {
			return err
		}
		defer os.RemoveAll(root)

		c, err := archive.Tar(root, archive.Uncompressed)
		if err != nil {
			return err
		}
		context = c
	} else if urlutil.IsURL(buildConfig.RemoteURL) {
		f, err := httputils.Download(buildConfig.RemoteURL)
		if err != nil {
			return err
		}
		defer f.Body.Close()
		dockerFile, err := ioutil.ReadAll(f.Body)
		if err != nil {
			return err
		}

		// When we're downloading just a Dockerfile put it in
		// the default name - don't allow the client to move/specify it
		buildConfig.DockerfileName = api.DefaultDockerfileName

		c, err := archive.Generate(buildConfig.DockerfileName, string(dockerFile))
		if err != nil {
			return err
		}
		context = c
	}
	defer context.Close()

	sf := streamformatter.NewJSONStreamFormatter()

	builder := &Builder{
		Daemon: d,
		OutStream: &streamformatter.StdoutFormater{
			Writer:          buildConfig.Stdout,
			StreamFormatter: sf,
		},
		ErrStream: &streamformatter.StderrFormater{
			Writer:          buildConfig.Stdout,
			StreamFormatter: sf,
		},
		Verbose:         !buildConfig.SuppressOutput,
		UtilizeCache:    !buildConfig.NoCache,
		Remove:          buildConfig.Remove,
		ForceRemove:     buildConfig.ForceRemove,
		Pull:            buildConfig.Pull,
		OutOld:          buildConfig.Stdout,
		StreamFormatter: sf,
		AuthConfig:      buildConfig.AuthConfig,
		ConfigFile:      buildConfig.ConfigFile,
		dockerfileName:  buildConfig.DockerfileName,
		cpuShares:       buildConfig.CpuShares,
		cpuPeriod:       buildConfig.CpuPeriod,
		cpuQuota:        buildConfig.CpuQuota,
		cpuSetCpus:      buildConfig.CpuSetCpus,
		cpuSetMems:      buildConfig.CpuSetMems,
		cgroupParent:    buildConfig.CgroupParent,
		memory:          buildConfig.Memory,
		memorySwap:      buildConfig.MemorySwap,
		cancelled:       buildConfig.WaitCancelled(),
	}

	id, err := builder.Run(context)
	if err != nil {
		return err
	}

	if repoName != "" {
		return d.Repositories().Tag(repoName, tag, id, true)
	}
	return nil
}

// IsValidRemote checks if the specified string is a valid remote (for builds)
func IsValidRemote(remote string) bool {
	return urlutil.IsGitURL(remote) || urlutil.IsURL(remote)
}